Author name code: imada ADS astronomy entries on 2022-09-14 author:"Imada, Shinsuke" ------------------------------------------------------------------------ Title: Inference of magnetic field during the Dalton minimum: Case study with recorded sunspot areas Authors: Uneme, Shoma; Imada, Shinsuke; Lee, Harim; Park, Eunsu; Hayakawa, Hisashi; Iju, Tomoya; Moon, Yong-Jae Bibcode: 2022PASJ...74..767U Altcode: The Dalton minimum is considered to be one of the unique solar activity periods that have been captured in direct sunspot observations since 1610. Specifically, the solar magnetic field in this period is of great interest. Derfflinger and Prantner's sunspot observations of 1802-1824 and 1800-1844 are the most important references for this period. To understand the solar magnetic activity in the Dalton minimum, it is important to estimate the latitude/longitude distribution of the sunspots and the sunspot areas for that duration. In this study, we analyze Derfflinger and Prantner's sunspot drawings to determine the sunspot parameters, particularly the sunspot area. We find that the sunspot areas obtained from Derfflinger's drawings are overemphasized by a factor of eight relative to those derived from modern observations. We also analyze Prantner's sunspot drawings to validate our analysis of Derfflinger's drawings. Further, we generate solar magnetograms from Derfflinger's sunspot drawings using a deep-learning model based on conditional generative adversarial networks. Our analysis of these sunspot areas will provide important information for restoring the magnetograms during the Dalton minimum. Title: A spectral solar irradiance monitor (SoSpIM) on the JAXA Solar-C (EUVST) space mission Authors: Harra, Louise K.; Watanabe, Kyoko; Haberreiter, Margit; Hori, Tomoaki; Hara, Hirohisa; Kretzschmar, Matthieu; Woods, Thomas; Shimizu, Toshifumi; Krucker, Samuel; Berghmans, David; Jin, Hidekatsu; Dominique, Marie; Eparvier, Francis G.; Gissot, Samuel; Leng Yeo, Kok; Pfiffner, Dany; Milligan, Ryan; Thiemann, Edward; Miyoshi, Yoshizumi; Imada, Shinsuke; Kawate, Tomoko; Chamberlin, Phillip; Rozanov, Eugene; Silvio Koller, -.; Barczynski, Krzysztof; Nozomu; Nishitani; Ieda, Akimasa; Langer, Patrick; Meier, Leandro; Tye, Daniel; Alberti, Andrea Bibcode: 2022cosp...44..834H Altcode: The JAXA Solar-C (EUVST) mission (Shimizu et al., 2020) is designed to comprehensively understand how mass and energy are transferred throughout the solar atmosphere. The EUV High-Throughput Spectroscopic Telescope (EUVST) onboard does this by observing all the temperature regimes of the atmosphere from the chromosphere to the corona simultaneously. To enhance the EUVST scientific capabilities, there will be a Solar Spectral Irradiance Monitor (SoSpIM). SoSpIM will work hand-in-hand scientifically with EUVST, by providing the full Sun irradiance at sub-second time cadence combined with the spatially resolved spectroscopy from EUVST. The SoSPIM instrument will specifically address two aspects. These are: · Understand how the solar atmosphere becomes unstable, releasing the energy that drives solar flares - achieved through probing fast time cadence solar flare variations. · Measuring solar irradiance that impacts the Earth's thermosphere and the mesosphere, linking to spatially resolved measurements of the solar atmosphere with EUVST. SoSpIM will provide high time resolution measurements in 2 channels (a) in the corona through channel 1 (EUV) and (b) in the lower atmosphere through channel 2 (Lyman alpha). Each channel impacts different layers of the Earth's atmosphere. Title: How Can Solar-C/SOSPIM Contribute to the Understanding of Quasi-Periodic Pulsations in Solar Flares? Authors: Dominique, Marie; Harra, Louise K.; Watanabe, Kyoko; Hara, Hirohisa; Zhukov, Andrei; Shimizu, Toshifumi; Berghmans, David; Dolla, Laurent; Gissot, Samuel; Pfiffner, Dany; Imada, Shinsuke; Silvio Koller, -.; Meier, Leandro; Tye, Daniel; Alberti, Andrea Bibcode: 2022cosp...44.2524D Altcode: Quasi-periodic pulsations (QPPs) refer to nearly-periodic oscillations that are often observed in irradiance time series during solar flares and have also been reported in several stellar flares. In the last years, several statistical studies based on Soft X-ray measurements have reached the conclusion that QPPs are present in most solar flares of class M and above. Still, as of today, we are still unsure of what causes QPPs. Several models could explain the presence of QPPs with periods matching the ones observed. More detailed analysis of the observational signatures of QPPs might help determine which of those models are actually playing a role in the generation of QPPs. However, as QPPs is a small timescale process (the period of QPPs is often reported to be less than a minute), such an analysis requires instruments with a good signal-to-noise and high sampling rate. In this context, the spectral solar irradiance monitor SOSPIM, that will be part of the JAXA SOLAR C mission and that will complement the EUVST spectrograph measurements, could be a valuable asset. SOSPIM will observe the solar chromosphere and corona in the Lyman-alpha and EUV spectral ranges at high cadence. In this presentation, we review the current knowledge of QPPs and describe what could be the contribution of SOSPIM to push their understanding one step forward. Title: Long-term variation in the solar terrestrial enviroment related to solar cycle Authors: Imada, Shinsuke; Tsujimura, Hodaka; Iijima, Haruhisa Bibcode: 2022cosp...44.1549I Altcode: It is known that the solar activity fluctuates in a cycle of about 11 years, and the global magnetic field structure of the sun changes with the fluctuation. This change in the magnetic field structure has a great effect on the solar wind from the sun into the interplanetary space, and as a result, the solar terrestrial environment also fluctuates in a cycle of about 11 years. In this research, we will stochastically discuss what the solar wind will look like in about 10 years by combining the following solar cycle activity prediction model and the solar wind model that we have developed so far. In this research, we will combine the next solar cycle activity prediction model and the solar wind model that we have been developing so far, and probabilistically discuss what the solar wind will look like about 10 years from now. In addition, we will verify whether the coronal hole generation, transportation, and disappearance on a time scale of several tens of days and the solar wind in the earth's orbit can be reproduced by our method using past observation results. Title: Magnetic Reconnection in the Solar Atmosphere: Future Plans for Reconnection Observations Authors: Imada, Shinsuke Bibcode: 2022cosp...44.1496I Altcode: Magnetic reconnection has been recognized as one of the key mechanisms for heating and bulk acceleration of space plasmas. To date, many observations have been made on the solar corona to confirm the presence of high-temperature and high-speed plasma flows produced by magnetic reconnection above flare arcades. In this talk, I will introduce the study on plasma heating considers the time-dependent ionization process during a large solar flare on 2017 September 10, observed by Hinode/EUV Imaging Spectrometer (EIS). The observed Fe XXIV/Fe XXIII ratios increase downstream of the reconnection outflow, and they are consistent with the time-dependent ionization effect at a constant electron temperature Te = 25 MK. Moreover, this study also shows that the nonthermal velocity, which can be related to the turbulent velocity, reduces significantly along the downstream of the reconnection outflow, even when considering the time-dependent ionization process. The number of high-temperature lines observed by Hinode/EIS is limited, so it is difficult to make a sufficient diagnosis of the reconnection region. Recently, the next generation solar observation satellite Solar-C (EUVST) has been discussed intensively. An ultraviolet imaging spectrometer with dramatically improved spatial and temporal resolution is planned for this satellite. In the Solar-C era, thermal nonequilibrium plasma will be extensively discussed. I expect that Solar-C (EUVST) will reveal the reconnection region in detail. Title: Factors That Determine the Power-law Index of an Energy Distribution of Solar Flares Authors: Kawai, Toshiki; Imada, Shinsuke Bibcode: 2022ApJ...931..113K Altcode: The power-law index of an occurrence frequency distribution of flares as a function of energy is one of the most important indicators to evaluate the contribution of small-scale flares to coronal heating. For a few decades, many studies tried to derive the power-law index using various instruments and methods. However, these results are various and the cause of this uncertainty is unknown due to the variety of observation conditions. Therefore, we investigated the dependence of the index on the solar activity, coronal features, released energy range, and active region properties such as magnetic flux, twist, and size. Our findings are (1) annual power-law index derived from time series of total solar irradiance (Sun-as-a-star observation analysis) has a negative correlation with sunspot number; (2) power-law index in active region is smaller than that of the quiet Sun and coronal holes; (3) power-law index is almost constant in the energy range of 1025 ≲ E ≲ 1030 erg; and (4) active regions that have more magnetic free energy density, unsigned magnetic flux, and shear angle tend to have smaller power-law indices. Based on the results and energy-scaling law of Petschek-type reconnection, we suggest that the power-law index of sunspot-scale events is smaller than that of granule-scale events. Moreover, we indicated that sunspot-scale events follow CSHKP flare model whereas granule-scale events follow Parker's nanoflare model. Title: Reproduction of the Earth's ionospheric response to solar flare emission spectra using physical-based models Authors: Nishimoto, Shohei; Watanabe, Kyoko; Jin, Hidekatsu; Kawai, Toshiki; Imada, Shinsuke; Kawate, Tomoko Bibcode: 2021AGUFMSH55C1855N Altcode: The X-rays and extreme ultraviolet (EUV) emitted during solar flares can rapidly change the physical composition of the Earth's ionosphere, causing sudden ionospheric disturbances and other space weather phenomena. (Dellinger 1937). Therefore, to understand how solar flare emission spectra affects the ionosphere, it is important to have an accurate understanding of the solar flare emission spectra. Solar flares with a long duration have a large effect on ionosphere because they have a large energy (Qian et al., 2010). The physics-based model is useful for accurately estimate the profile of solar flare emission. We verify the extent of reproducing the flare emission spectra using a newly proposed method based on the physical process of the flare loop (Kawai et al., 2020). In this method, we convert the soft X-ray light-curves observed during flare events into EUV emission spectra using a one-dimensional hydrodynamic calculation and the CHIANTI atomic database (Dere et al., 2019). We examined the EUV flare time-integrated irradiance and EUV flare line rise time for 21 flare events by comparing the calculation results of the proposed method and observed EUV spectral data. Proposed method succeeded in reproducing the EUV flare time-integrated irradiance of Fe lines which have relatively higher formation temperature. For the EUV flare line rise time, there was acceptable correlation between the proposed method estimations and observations for all Fe flare emission lines. We used the solar flare emission spectral models and the Earth's whole atmospheric model to study the effect of X-rays and EUV emissions from flares on the ionosphere. For the solar flare emission spectral models, we used the physical model described above and an empirical model, the Flare Irradiance Spectral Model (FISM; Chamberlin et al., 2020). For the Earth's whole atmospheric model, we used the Ground-to-Topside Model of Atmosphere and Ionosphere for Aeronomy (GAIA; Jin et al., 2011). We compared the total electron content (TEC) variations corresponding to various solar flare emission spectra for 6 X-class flare events that occurred from 2010 to the 2021. The results show that the wavelengths of solar flare emissions that mainly affect TEC variations are soft X-rays (<10 nm) and EUV emissions (especially 28-30, 32-34 nm). Title: How Can Solar-C/SOSPIM Contribute to the Understanding of Quasi-Periodic Pulsations in Solar Flares? Authors: Dominique, Marie; Dolla, Laurent; Zhukov, Andrei; Alberti, Andrea; Berghmans, David; Gissot, Samuel; Hara, Hirohisa; Harra, Louise; Imada, Shinsuke; Koller, Silvio; Meier, Leandro; Pfiffner, Daniel; Shimizu, Toshifumi; Tye, Daniel; Watanabe, Kyoko Bibcode: 2021AGUFMSH25E2124D Altcode: Quasi-periodic pulsations (QPPs) refer to nearly-periodic oscillations that are often observed in irradiance time series during solar flares and have also been reported in several stellar flares. In the last years, several statistical studies based on Soft X-ray measurements have reached the conclusion that QPPs are present in most solar flares of class M and above. Still, the mechanism at the origin of QPPs is under debate. Are they caused by waves or periodic fluctuations of the magnetic reconnection driving the flare? Analyzing the characteristics of QPPs and their evolution during the flare could help identifying their origin. However, QPPs sometimes exhibit very different periodicities, and do not always happen during the same phase of the flare. All this could point to the coexistence of QPPs with different origin mechanism, and indicates the need for more observations. In this context, the spectral solar irradiance monitor SOSPIM, that will be part of the JAXA SOLAR C mission and that will complement the EUVST spectrograph measurements, could be a valuable asset. SOSPIM will observe the solar chromosphere and corona in the Lyman-alpha and EUV spectral ranges at high cadence. In this presentation, we review the current knowledge of QPPs and describe what could be the contribution of SOSPIM to push their understanding one step forward. Title: Validation of computed extreme ultraviolet emission spectra during solar flares Authors: Nishimoto, Shohei; Watanabe, Kyoko; Kawai, Toshiki; Imada, Shinsuke; Kawate, Tomoko Bibcode: 2021EP&S...73...79N Altcode: X-rays and extreme ultraviolet (EUV) emissions from solar flares rapidly change the physical composition of the Earth's thermosphere and ionosphere, thereby causing space weather phenomena such as communication failures. Numerous empirical and physical models have been developed to estimate the effects of flare emissions on the Earth's upper atmosphere. We verified the reproduction of the flare emission spectra using a one-dimensional hydrodynamic calculation and the CHIANTI atomic database. To validate the proposed model, we used the observed EUV spectra obtained by the Extreme ultraviolet variability experiment (EVE) on board the Solar Dynamics Observatory (SDO). We examined the "EUV flare time-integrated irradiance" and "EUV flare line rise time" of the EUV emissions for 21 events by comparing the calculation results of the proposed model and observed EUV spectral data. The proposed model successfully reproduced the EUV flare time-integrated irradiance of the Fe VIII 131 Å, Fe XVIII 94 Å, and Fe XX133 Å, as well as the 55-355 Å and 55-135 Å bands. For the EUV flare line rise time, there was an acceptable correlation between the proposed model estimations and observations for all Fe flare emission lines. These results demonstrate that the proposed model can reproduce the EUV flare emission spectra from the emitting plasma with a relatively high formation temperature. This indicates that the physics-based model is effective for the accurate reproduction of the EUV spectral irradiance. Title: Model-based reproduction and validation of the total spectra of a solar flare and their impact on the global environment at the X9.3 event of September 6, 2017 Authors: Watanabe, Kyoko; Jin, Hidekatsu; Nishimoto, Shohei; Imada, Shinsuke; Kawai, Toshiki; Kawate, Tomoko; Otsuka, Yuichi; Shinbori, Atsuki; Tsugawa, Takuya; Nishioka, Michi Bibcode: 2021EP&S...73...96W Altcode: We attempted to reproduce the total electron content (TEC) variation in the Earth's atmosphere from the temporal variation of the solar flare spectrum of the X9.3 flare on September 6, 2017. The flare spectrum from the Flare Irradiance Spectral Model (FISM), and the flare spectrum from the 1D hydrodynamic model, which considers the physics of plasma in the flare loop, are used in the GAIA model, which is a simulation model of the Earth's whole atmosphere and ionosphere, to calculate the TEC difference. We then compared these results with the observed TEC. When we used the FISM flare spectrum, the difference in TEC from the background was in a good agreement with the observation. However, when the flare spectrum of the 1D-hydrodynamic model was used, the result varied depending on the presence or absence of the background. This difference depending on the models is considered to represent which extreme ultraviolet (EUV) radiation is primarily responsible for increasing TEC. From the flare spectrum obtained from these models and the calculation result of TEC fluctuation using GAIA, it is considered that the enhancement in EUV emission by approximately 15-35 nm mainly contributes in increasing TEC rather than that of X-ray emission, which is thought to be mainly responsible for sudden ionospheric disturbance. In addition, from the altitude/wavelength distribution of the ionization rate of Earth's atmosphere by GAIA (Ground-to-topside Atmosphere and Ionosphere model for Aeronomy), it was found that EUV radiation of approximately 15-35 nm affects a wide altitude range of 120-300 km, and TEC enhancement is mainly caused by the ionization of nitrogen molecules. Title: PSTEP: project for solar-terrestrial environment prediction Authors: Kusano, Kanya; Ichimoto, Kiyoshi; Ishii, Mamoru; Miyoshi, Yoshizumi; Yoden, Shigeo; Akiyoshi, Hideharu; Asai, Ayumi; Ebihara, Yusuke; Fujiwara, Hitoshi; Goto, Tada-Nori; Hanaoka, Yoichiro; Hayakawa, Hisashi; Hosokawa, Keisuke; Hotta, Hideyuki; Hozumi, Kornyanat; Imada, Shinsuke; Iwai, Kazumasa; Iyemori, Toshihiko; Jin, Hidekatsu; Kataoka, Ryuho; Katoh, Yuto; Kikuchi, Takashi; Kubo, Yûki; Kurita, Satoshi; Matsumoto, Haruhisa; Mitani, Takefumi; Miyahara, Hiroko; Miyoshi, Yasunobu; Nagatsuma, Tsutomu; Nakamizo, Aoi; Nakamura, Satoko; Nakata, Hiroyuki; Nishizuka, Naoto; Otsuka, Yuichi; Saito, Shinji; Saito, Susumu; Sakurai, Takashi; Sato, Tatsuhiko; Shimizu, Toshifumi; Shinagawa, Hiroyuki; Shiokawa, Kazuo; Shiota, Daikou; Takashima, Takeshi; Tao, Chihiro; Toriumi, Shin; Ueno, Satoru; Watanabe, Kyoko; Watari, Shinichi; Yashiro, Seiji; Yoshida, Kohei; Yoshikawa, Akimasa Bibcode: 2021EP&S...73..159K Altcode: Although solar activity may significantly impact the global environment and socioeconomic systems, the mechanisms for solar eruptions and the subsequent processes have not yet been fully understood. Thus, modern society supported by advanced information systems is at risk from severe space weather disturbances. Project for solar-terrestrial environment prediction (PSTEP) was launched to improve this situation through synergy between basic science research and operational forecast. The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. By this project, we sought to answer the fundamental questions concerning the solar-terrestrial environment and aimed to build a next-generation space weather forecast system to prepare for severe space weather disasters. The PSTEP consists of four research groups and proposal-based research units. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced. Title: Johann Christoph Müller's Sunspot Observations in 1719 - 1720: Snapshots of the Immediate Aftermath of the Maunder Minimum Authors: Hayakawa, Hisashi; Iju, Tomoya; Kuroyanagi, Chiaki; Carrasco, Víctor M. S.; Besser, Bruno P.; Uneme, Shoma; Imada, Shinsuke Bibcode: 2021SoPh..296..154H Altcode: The Maunder Minimum (1645 - 1715) was unique in terms of solar-cycle amplitudes and sunspot-position distributions registered in the last four centuries; however, little is known for its recovery and transition to the regular solar cycles until 1749 and the existing reconstructions vary from one to another here. This article presents a snapshot of Solar Cycle −3 including sunspot observations by Johann Christoph Müller (hereafter, JCM) in 1719 - 1720. We identified his sunspot drawings in the manuscript department of the National Library of Russia in St. Petersburg and compiled his biographical profile and observational expertise. Subsequently, we analysed his sunspot drawings and derived the group number and positions of the observed sunspots. The results and comparative analyses with contemporary observations revealed that JCM reported up to five sunspot groups, corresponding well with Sebastian Alischer's records but contrasting with Johann Rost's records in the existing databases. These comparisons indicated that Rost's extremely large values recorded in 1719 - 1720 probably represented individual sunspot numbers instead of sunspot group numbers, unlike the understanding in the existing databases. Accordingly, JCM's group number forms a robust reference for representing the solar activity in 1719 - 1720 and exhibits relatively moderate solar cycle amplitude in the immediate aftermath of the Maunder Minimum. Moreover, JCM's sunspot drawings provide significantly detailed information on sunspot positions. Our analyses could locate the reported sunspot groups in both solar hemispheres, unlike those in the Maunder Minimum, which support the suggested transition between Solar Cycles −4 and −3. Title: Stephan Prantner's Sunspot Observations during the Dalton Minimum Authors: Hayakawa, Hisashi; Uneme, Shoma; Besser, Bruno P.; Iju, Tomoya; Imada, Shinsuke Bibcode: 2021ApJ...919....1H Altcode: 2021arXiv210505405H In addition to regular Schwabe cycles (≍11 yr), solar variability also shows longer periods of enhanced or reduced activity. Of these, reconstructions of the Dalton Minimum provide controversial sunspot group numbers and limited sunspot positions, partially due to limited source record accessibility. In this context, we analyzed Stephan Prantner's sunspot observations spanning from 1804 to 1844, the values of which had only been known through estimates despite their notable chronological coverage during the Dalton Minimum. We identified his original manuscript in Stiftsarchiv Wilten, near Innsbruck (Austria). We reviewed his biography (1782-1873) and located his observational sites at Wilten and Waidring, which housed the principal telescopes for his early and late observations: a 3.5 inch astronomical telescope and a Reichenbach 4 foot achromatic erecting telescope, respectively. We identified 215 days of datable sunspot observations, which is almost twice as much data as his estimated data in the existing databases (=115 days). In Prantner's records, we counted up to seven to nine sunspot groups per day and measured sunspot positions, which show their distributions in both solar hemispheres. These results strikingly emphasize the difference between the Dalton Minimum and the Maunder Minimum as well as the similarity between the Dalton Minimum and the weak solar cycles in the modern observations. Title: Reanalyses of the sunspot observations of Fogelius and Siverus: two 'long-term' observers during the Maunder minimum Authors: Hayakawa, Hisashi; Iju, Tomoya; Uneme, Shoma; Besser, Bruno P.; Kosaka, Shunsuke; Imada, Shinsuke Bibcode: 2021MNRAS.506..650H Altcode: 2020MNRAS.tmp.2883H; 2020arXiv200914369H The solar activity during the Maunder minimum (MM; 1645-1715) has been considered significantly different from the one captured in modern observations, in terms of sunspot group number and sunspot positions, whereas its actual amplitudes and distributions are still under active discussions. In its core period (1650/1660-1700), Martin Fogelius and Heinrich Siverus have formed significant long-term series in the existing data bases. With numerous spotless days, they have been considered as the 13th and 7th most active observers before the end of the MM. In this study, we have analysed their original archival records, revised their data, have removed significant contaminations of the apparent 'spotless days' in the existing data bases, and cast caveats on the potential underestimation of the solar-cycle amplitude in the core MM. Still, they reported at best one sunspot group throughout their observational period and confirm the significantly suppressed solar cycles during the MM. This is also supported from the contemporary observations of Hook and Willoughby, analysed in this study. Based on their revised data, we have also derived positions of notable sunspot groups, which Siverus recorded in 1671 (≍N7.5° ± 2.5°), in comparison with those of Cassini's drawings (≍N10° ± 1°). Their coincidence in position and chronology in corrected dates indicates these sunspot groups were probably the same recurrent active region (AR) and its lifespan was significantly long (≥35 d) even during the MM. Title: The Energy Conversion Rate of an Active Region Transient Brightening Estimated by Hinode Spectroscopic Observations Authors: Kawai, Toshiki; Imada, Shinsuke Bibcode: 2021ApJ...918...51K Altcode: 2021arXiv210606208K We statistically estimate the conversion rate of the energy released during an active region transient brightening to Doppler motion and thermal and nonthermal energies. We used two types of data sets for the energy estimation and detection of transient brightenings. One includes spectroscopic images of Fe XIV, Fe XV, and Fe XVI lines observed by the Hinode/EUV Imaging Spectrometer. The other includes images obtained from the 211 Å channel of the Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA). The observed active region was NOAA 11890 on 2013 November 9 and 10. As a result, the released Doppler motion and nonthermal energies were found to be approximately 0.1%-1% and 10%-100% of the change in the amount of thermal energy in each enhancement, respectively. Using this conversion rate, we estimated the contribution of the total energy flux of AIA transient brightenings to the active region heating to be at most 2% of the conduction and radiative losses. Title: A New Broadening Technique of the Numerically Unresolved Solar Transition Region and Its Effect on the Spectroscopic Synthesis Using Coronal Approximation Authors: Iijima, Haruhisa; Imada, Shinsuke Bibcode: 2021ApJ...917...65I Altcode: 2021arXiv210600864I The transition region is a thin layer of the solar atmosphere that controls the energy loss from the solar corona. Large numbers of grid points are required to resolve this thin transition region fully in numerical modeling. In this study, we propose a new numerical treatment, called LTRAC, which can be easily extended to the multidimensional domains. We have tested the proposed method using a one-dimensional hydrodynamic model of a coronal loop in an active region. The LTRAC method enables modeling of the transition region with a numerical grid size of 50-100 km, which is about 1000 times larger than the physically required value. We used the velocity differential emission measure to evaluate the possible effects on the optically thin emission. Lower-temperature emissions were better reproduced by the LTRAC method than by previous methods. Doppler shift and nonthermal width of the synthesized line emission agree with those from a high-resolution reference simulation within an error of several kilometers per second above the formation temperature of 105 K. Title: Nonequilibrium Ionization Plasma during a Large Solar Limb Flare Observed by Hinode/EIS Authors: Imada, S. Bibcode: 2021ApJ...914L..28I Altcode: 2021arXiv210514660I This study on plasma heating considers the time-dependent ionization process during a large solar flare on 2017 September 10, observed by Hinode/EUV Imaging Spectrometer (EIS). The observed Fe XXIV/Fe XXIII ratios increase downstream of the reconnection outflow, and they are consistent with the time-dependent ionization effect at a constant electron temperature Te 25 MK. Moreover, this study also shows that the nonthermal velocity, which can be related to the turbulent velocity, reduces significantly along the downstream of the reconnection outflow, even when considering the time-dependent ionization process. Title: Instrumental design of the Solar Observing Satellite: solar-C_EUVST Authors: Suematsu, Yoshinori; Shimizu, Toshifumi; Hara, Hirohisa; Kawate, Tomoko; Katsukawa, Yukio; Ichimoto, Kiyoshi; Imada, Shinsuke Bibcode: 2021SPIE11852E..3KS Altcode: The EUV High-Throughput Spectroscopic Telescope (EUVST) of Solar-C mission is a revolutionary spectrometer that is designed to provide high-quality and high cadence spectroscopic data covering a wide temperature range of the chromosphere to flaring corona to investigate the energetics and dynamics of the solar atmosphere. The EUVST consists of only two imaging optical components; a 28-cm clear aperture off-axis parabolic primary mirror and a two-split ellipsoidal grating without a blocking filter for visible light before the primary mirror to achieve unprecedented high spatial and temporal resolution in EUV-UV imaging spectroscopic observations. For this reason, about 53 W of sunlight is absorbed by the multilayer coating on the mirror. We present an instrumental design of the telescope, particularly, primary mirror assembly which enables slit-scan observations for imaging spectroscopy, an image stabilizing tip-tilt control, and a focus adjustment on orbit, together with an optomechanical design of the primary mirror and its supporting system which gives optically tolerant wavefront error against a large temperature increase due to an absorption of visible and IR lights. Title: Sunspot Observations at the Eimmart Observatory and in Its Neighborhood during the Late Maunder Minimum (1681-1718) Authors: Hayakawa, Hisashi; Kuroyanagi, Chiaki; Carrasco, Víctor M. S.; Uneme, Shoma; Besser, Bruno P.; Sôma, Mitsuru; Imada, Shinsuke Bibcode: 2021ApJ...909..166H Altcode: The Maunder Minimum (1645-1715; hereafter MM) is generally considered as the only grand minimum in the chronological coverage of telescopic sunspot observations. Characterized by scarce sunspot occurrences and their asymmetric concentrations in the southern solar hemisphere, the MM has frequently been associated with a special state of solar dynamo activity. As such, it is important to analyze contemporary observational records and improve our understanding of this peculiar interval, whereas the original records are frequently preserved in historical archives and can be difficult to access. In this study, we consult historical archives in the National Library of Russia, St. Petersburg, and analyze a series of sunspot observations conducted at the Eimmart Observatory from 1681 to 1709, which is the second-richest sunspot data set produced during the MM, following La Hire's series, among existing data sets. We have further extended our analyses to neighboring observations to extend our investigations up to 1718. We first analyze source documents and descriptions of observational instruments. Our analyses have significantly revised the existing data set, removed contaminations, and updated and labeled them as Eimmart Observatory (78 days), Altdorf Observatory (4 days), Hoffmann (22 days), and Wideburg (25 days). The revisions have updated the temporal coverage of the contemporary sunspot observations from 73.4% to 66.9% from 1677 to 1709. We have also derived the positions of the observed sunspot groups in comparison with contemporary observations. Our results indicate hemispheric asymmetry in the MM and recovery of sunspot groups in both hemispheres after 1716, supporting the common paradigm of the MM. Title: Derfflinger's Sunspot Observations: Primary Dataset to Understand the Dalton Minimum Authors: Hayakawa, Hisashi; Besser, Bruno P.; Imada, Shinsuke; Arlt, Rainer; Iju, Tomoya; Bourdin, Philippe; Kraml, Amand; Uneme, Shoma Bibcode: 2021cosp...43E.915H Altcode: As various predictions indicate possible arrival of depressed solar cycles or even a secular/grand solar minimum, it is increasingly important to understand the actual solar activity during the existing solar secular/grand minima. The Dalton Minimum is arguably one of such solar secular/grand minima within the coverage of telescopic sunspot observations, while its sunspot group number has been differently reconstructed by various studies and its butterfly diagram has not been reconstructed. Here, we examine the original observational records of Derfflinger in Krememünster Observatory, spanning from 1802 to 1824, covering the core period of the Dalton Minimum. We revise his sunspot group number and reconstruct the butterfly diagram. These reconstructions show that the Dalton Minimum was significantly different from the Maunder Minimum, both in terms of amplitude of its solar cycles and sunspot distributions. Title: Science Objectives and Current Status of Solar-C_EUVST Authors: Imada, Shinsuke Bibcode: 2021cosp...43E1790I Altcode: SolarC EUVST is designed to comprehensively understand the energy and mass transfer from the solar surface to the solar corona and interplanetary space, and to investigate the elementary processes that take place universally in cosmic plasmas. The proposed mission is a fundamental step for answering how the plasma universe is created and evolves, and how the Sun influences the Earth and other planets in our solar system. The two primary science objectives for SolarC EUVST are : I) Understand how fundamental processes lead to the formation of the solar atmosphere and the solar wind, II) Understand how the solar atmosphere becomes unstable, releasing the energy that drives solar flares and eruptions. SolarC EUVST will, A) seamlessly observe all the temperature regimes of the solar atmosphere from the chromosphere to the corona at the same time, B) resolve elemental structures of the solar atmosphere with high spatial resolution and cadence to track their evolution, and C) obtain spectroscopic information on the dynamics of elementary processes taking place in the solar atmosphere. In this talk, we will first discuss the science target of the SolarC EUVST, and discuss the science topic associated flare in detail. Photospheric motions lead to the accumulation of free magnetic energy in the corona. This system eventually becomes unstable, releasing the energy through magnetic reconnection. This process of energy conversion heats the plasma to high temperatures and drives coronal mass ejections (CMEs). By measuring the properties of multi-temperature flaring plasma, SolarC EUVST will investigate why the reconnection is fast despite the high magnetic Reynolds number. It will also monitor the temporal evolution of solar active regions and identify the triggering mechanism for the flare and eruption. We will discuss the science objectives "Understand the Fast Magnetic Reconnection Process" and "Identify the Signatures of Global Energy Buildup and the Local Triggering of the Flare and Eruption". We also report the current status of SolarC EUVST. Title: Energy Distribution of Small-scale Flares Derived Using a Genetic Algorithm Authors: Kawai, Toshiki; Imada, Shinsuke Bibcode: 2021ApJ...906....2K Altcode: 2020arXiv201106390K To understand the mechanism of coronal heating, it is crucial to derive the contribution of small-scale flares, the so-called nanoflares, to the heating up of the solar corona. To date, several studies have tried to derive the occurrence frequency distribution of flares as a function of energy to reveal the contribution of small-scale flares. However, there are no studies that derive the distribution with considering the following conditions: (1) evolution of the coronal loop plasma heated by small-scale flares, (2) loops smaller than the spatial resolution of the observed image, and (3) multiwavelength observation. To take into account these conditions, we introduce a new method to analyze small-scale flares statistically based on a one-dimensional loop simulation and a machine-learning technique, that is, the genetic algorithm. First, we obtain six channels of Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) light curves of the active-region coronal loops. Second, we carry out many coronal loop simulations and obtain the SDO/AIA light curves for each simulation in a pseudo-manner. Third, using the genetic algorithm, we estimate the best combination of simulated light curves that reproduce the observation. Consequently, the observed coronal loops are heated by small-scale flares with energy flux larger than that typically required to heat up an active region intermittently. Moreover, we derive the occurrence frequency distribution which has various power-law indices in the range from 1-3, which partially supports the nanoflare heating model. In contrast, we find that 90% of the coronal heating is done by flares that have energy larger than 1025 erg. Title: Estimation of solar flare loop length by machine learning Authors: Nishimoto, S.; Kawai, T.; Watanabe, K.; Imada, S. Bibcode: 2020AGUFMNG0040014N Altcode: X-rays and extreme ultraviolet (EUV) emissions from solar flares rapidly change the physical composition of the Earth's thermosphere and ionosphere, thereby causing space weather phenomena such as communication failures. To predict the effects of flare emissions on the Earth's upper atmosphere and the occurrence of communication failures, numerous empirical and physical models have been developed which derive the flare spectral changes.

We have established a method to reproduce the flare loop emission using one-dimensional hydrodynamic calculation and the CHIANTI atomic database (Kawai et al., 2020). This method has successfully reproduced the time-integrated irradiance and time evolution of flare EUV lines. An important input parameter when using this method is the flare loop length. If the flare loop length can be estimated from the information of the Sun before flare, flare emissions can be estimated before the occurrence of flare by this method.

In this study, we attempted to estimate the flare ribbon distance related to the flare loop length from the observed images before flare using some machine learning techniques such as Convolutional Neural Network (CNN). We used active region images by Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO) and loop images before flare by Atmospheric Imaging Assembly (AIA) onboard SDO as input to machine learning method. We obtained the ribbon distance from the observations of SDO/AIA 1600 Å as teacher data.

we tried to construct a CNN model using all flare events greater than M class observed by SDO. The CNN model, which uses the active area image as input, can estimate the ribbon distance with error within 45% for majority events. This result indicates that it is possible to estimate the ribbon distance from the active region image with a certain level accuracy.

In this presentation, we report the accuracy and latest results of the models for estimating the flare loop length from solar multi-wavelength real-time observations. Title: Reproduction and validation of flare spectra and their impact on the global environment Authors: Watanabe, K.; Jin, H.; Nishimoto, S.; Imada, S.; Kawai, T.; Kawate, T. Bibcode: 2020AGUFMSM050..02W Altcode: It is well known that sudden increase of flare emissions accelerates the ionization and molecular dissociation of atmospheric components in the ionosphere and thermosphere, and it may cause the sudden ionospheric disturbance (SID). And then, communication failure also caused by the absorption of the short-wave by the SID is known as the Dellinger phenomenon (Dellinger 1937). In order to predict the occurrence of the Dellinger phenomenon, we must know the relationship with the flare emission which causes the Dellinger phenomenon. Therefore, in order to verify which wavelength of the solar flare spectrum influence the occurrence of the Dellinger phenomenon, we have developed a method to calculate the solar flare radiation spectrum and its effect on the Earth's atmosphere. For the flare emission, we constructed new model with physical processes (Imada et al. 2015, Kawai et al. 2020). In our model, the physical process of the plasma in the flare loop is reproduced by combining the one-dimensional hydrodynamic calculation using CANS (Coordinated Astronomical Numerical Software) 1D package with the CHIANTI atomic database (Dere et al. 2019). Then, in order to examine the effect of flare emission on the Earth's atmosphere, we put our calculated flare spectra into the Earth's atmospheric model GAIA (Ground-to-Topside Model of Atmosphere and Ionosphere for Aeronomy; Jin et al., 2011). Finally, we tried to reproduce the total electron content (TEC) variation for some flare events, then we compared calculated results with the observed TEC amount. Especially when we investigated about the X9.3 flare on September 6, 2017, it is considered that the EUV emission about 15-40 nm is mainly affected increasing TEC. This result was also confirmed from the altitude/wavelength distribution of the ionization rate of Earth's atmosphere by GAIA. Title: Solar cycle-related variation in solar differential rotation and meridional flow in solar cycle 24 Authors: Imada, Shinsuke; Matoba, Kengo; Fujiyama, Masashi; Iijima, Haruhisa Bibcode: 2020EP&S...72..182I Altcode: We studied temporal variation of the differential rotation and poleward meridional circulation during solar cycle 24 using the magnetic element feature tracking technique. We used line-of-sight magnetograms obtained using the helioseismic and magnetic imager aboard the Solar Dynamics Observatory from May 01, 2010 to March 26, 2020 (for almost the entire period of solar cycle 24, Carrington rotation from 2096 to 2229) and tracked the magnetic element features every 1 h. We also estimated the differential rotation and poleward meridional flow velocity profiles. The observed profiles are consistent with those of previous studies on different cycles. Typical properties resulting from torsional oscillations can also be observed from solar cycle 24. The amplitude of the variation was approximately ±10 m s-1. Interestingly, we found that the average meridional flow observed in solar cycle 24 is faster than that observed in solar cycle 23. In particular, during the declining phase of the cycle, the meridional flow of the middle latitude is accelerated from 10 to 17 m s-1, which is almost half of the meridional flow itself. The faster meridional flow in solar cycle 24 might be the result of the weakest cycle during the last 100 years. Title: The Solar-C (EUVST) mission: the latest status Authors: Shimizu, Toshifumi; Imada, Shinsuke; Kawate, Tomoko; Suematsu, Yoshinori; Hara, Hirohisa; Tsuzuki, Toshihiro; Katsukawa, Yukio; Kubo, Masahito; Ishikawa, Ryoko; Watanabe, Tetsuya; Toriumi, Shin; Ichimoto, Kiyoshi; Nagata, Shin'ichi; Hasegawa, Takahiro; Yokoyama, Takaaki; Watanabe, Kyoko; Tsuno, Katsuhiko; Korendyke, Clarence M.; Warren, Harry; De Pontieu, Bart; Boerner, Paul; Solanki, Sami K.; Teriaca, Luca; Schuehle, Udo; Matthews, Sarah; Long, David; Thomas, William; Hancock, Barry; Reid, Hamish; Fludra, Andrzej; Auchère, Frederic; Andretta, Vincenzo; Naletto, Giampiero; Poletto, Luca; Harra, Louise Bibcode: 2020SPIE11444E..0NS Altcode: Solar-C (EUVST) is the next Japanese solar physics mission to be developed with significant contributions from US and European countries. The mission carries an EUV imaging spectrometer with slit-jaw imaging system called EUVST (EUV High-Throughput Spectroscopic Telescope) as the mission payload, to take a fundamental step towards answering how the plasma universe is created and evolves and how the Sun influences the Earth and other planets in our solar system. In April 2020, ISAS (Institute of Space and Astronautical Science) of JAXA (Japan Aerospace Exploration Agency) has made the final down-selection for this mission as the 4th in the series of competitively chosen M-class mission to be launched with an Epsilon launch vehicle in mid 2020s. NASA (National Aeronautics and Space Administration) has selected this mission concept for Phase A concept study in September 2019 and is in the process leading to final selection. For European countries, the team has (or is in the process of confirming) confirmed endorsement for hardware contributions to the EUVST from the national agencies. A recent update to the mission instrumentation is to add a UV spectral irradiance monitor capability for EUVST calibration and scientific purpose. This presentation provides the latest status of the mission with an overall description of the mission concept emphasizing on key roles of the mission in heliophysics research from mid 2020s. Title: Current Status of the Solar-C_EUVST Mission Authors: Imada, S.; Shimizu, T.; Kawate, T.; Toriumi, S.; Katsukawa, Y.; Kubo, M.; Hara, H.; Suematsu, Y.; Ichimoto, K.; Watanabe, T.; Watanabe, K.; Yokoyama, T.; Warren, H.; Long, D.; Harra, L. K.; Teriaca, L. Bibcode: 2020AGUFMSH056..05I Altcode: Solar-C_EUVST (EUV High-Throughput Spectroscopic Telescope) is designed to comprehensively understand the energy and mass transfer from the solar surface to the solar corona and interplanetary space, and to investigate the elementary processes that take place universally in cosmic plasmas. As a fundamental step towards answering how the plasma universe is created and evolves, and how the Sun influences the Earth and other planets in our solar system, the proposed mission is designed to comprehensively understand how mass and energy are transferred throughout the solar atmosphere. Understanding the solar atmosphere, which connects to the heliosphere via radiation, the solar wind and coronal mass ejections, and energetic particles is pivotal for establishing the conditions for life and habitability in the solar system.

The two primary science objectives for Solar-C_EUVST are : I) Understand how fundamental processes lead to the formation of the solar atmosphere and the solar wind, II) Understand how the solar atmosphere becomes unstable, releasing the energy that drives solar flares and eruptions. Solar-C_EUVST will, A) seamlessly observe all the temperature regimes of the solar atmosphere from the chromosphere to the corona at the same time, B) resolve elemental structures of the solar atmosphere with high spatial resolution and cadence to track their evolution, and C) obtain spectroscopic information on the dynamics of elementary processes taking place in the solar atmosphere.

In this talk, we will first discuss the science target of the Solar-C_EUVST, and then discuss the current status of the Solar-C_EUVST mission. Title: Thermal design of the Solar-C (EUVST) telescope Authors: Suematsu, Yoshinori; Shimizu, Toshifumi; Hara, Hirohisa; Kawate, Tomoko; Katsukawa, Yukio; Ichimoto, Kiyoshi; Imada, Shinsuke; Nagae, Kazuhiro; Yamazaki, Atsumu; Hattori, Tomoya Bibcode: 2020SPIE11444E..3KS Altcode: The EUV High-Throughput Spectroscopic Telescope (EUVST) of Solar-C mission consists of only two imaging optical components; a 28-cm clear aperture off-axis parabolic primary mirror and a two-split ellipsoidal grating without a blocking filter for visible light before the primary mirror to achieve unprecedented high spatial and temporal resolution in EUV-UV imaging spectroscopic observations. For this reason, about 60 W of sunlight is absorbed by the multilayer coating on the mirror. We report a thermal design of telescope in which the temperature of the primary mirror bonding part and underlying tip-tilt and slit-scanning mechanisms is well lower than a glass transition temperature of adhesive (about 60°C) and thermal deformation of the primary mirror is small, although it is non-negligibly small. Title: A sensitivity analysis of the updated optical design for EUVST on the Solar-C mission Authors: Kawate, Tomoko; Tsuzuki, Toshihiro; Shimizu, Toshifumi; Imada, Shinsuke; Katsukawa, Yukio; Hara, Hirohisa; Suematsu, Yoshinori; Ichimoto, Kiyoshi; Hattori, Tomoya; Narasaki, Shota; Warren, Harry P.; Teriaca, Luca; Korendyke, Clarence M.; Brown, Charles M.; Auchere, Frederic Bibcode: 2020SPIE11444E..3JK Altcode: The EUV high-throughput spectroscopic telescope (EUVST) onboard the Solar-C mission has the high spatial (0.4'') resolution over a wide wavelength range in the vacuum ultraviolet. To achieve high spatial resolution under a design constraint given by the JAXA Epsilon launch vehicle, we further update the optical design to secure margins needed to realize 0.4'' spatial resolution over a field of view of 100''×100''. To estimate the error budgets of spatial and spectral resolutions due to installation and fabrication errors, we perform a sensitivity analysis for the position and orientation of each optical element and for the grating parameters by ray tracing with the Zemax software. We obtain point spread functions (PSF) for rays from 9 fields and at 9 wavelengths on each detector by changing each parameter slightly. A full width at half maximum (FWHM) of the PSF is derived at each field and wavelength position as a function of the perturbation of each optical parameter. Assuming a mount system of each optical element and an error of each optical parameter, we estimate spatial and spectral resolutions by taking installation and fabrication errors into account. The results of the sensitivity analysis suggest that budgets of the total of optical design and the assembly errors account for 15% and 5.8% of our budgets of the spatial resolution in the long wavelength and short wavelength bands, respectively. On the other hand, the grating fabrication errors give a large degradation of spatial and spectral resolutions, and investigations of compensators are needed to relax the fabrication tolerance of the grating surface parameters. Title: Statistical Analysis of Asymmetric Sunspot Decay Observed by Hinode Authors: Imada, Shinsuke; Kato, Shota; Fujiyama, Masashi Bibcode: 2020SoPh..295..154I Altcode: We statistically studied the transport of magnetic flux in and around sunspots using a magnetic-element tracking technique to investigate whether sunspot-decay processes are isotropic. Using this method, we detected moving magnetic features (MMFs). The observed radius of an MMFs region was approximately 1.7 times the sunspot radius; furthermore, the average apparent velocity of MMFs was statistically estimated to be approximately 350 ms−1. We determined that the leading sunspots transport approximately 5% more magnetic flux to the Equator side than to the Pole side of the sunspots. In addition, the leading sunspots transport approximately 3% more magnetic flux to the back (East) than to the front (West) of the sunspots. On the other hand, the following sunspots do not show the magnetic-flux transport asymmetry. The statistics might not be sufficient for the analysis of the following sunspots. These asymmetries of magnetic flux transport might contribute to the cross-equatorial transport of net magnetic flux, which is an important physical quantity of polar magnetic-field reversal. Title: Statistical and Observational Research on Solar Flare EUV Spectra and Geometrical Features Authors: Nishimoto, Shohei; Watanabe, Kyoko; Imada, Shinsuke; Kawate, Tomoko; Lee, Kyoung-Sun Bibcode: 2020ApJ...904...31N Altcode: We performed statistical analysis on the flare emission data to examine parameters related to the flare extreme-ultraviolet (EUV) spectra. This study used the data from the Geostationary Operational Environmental Satellite X-ray Sensors to determine the fundamental flare parameters. The relationship between soft X-ray data and EUV emission data observed by the Extreme Ultraviolet Variability Experiment on board the Solar Dynamics Observatory (SDO) MEGS-A was investigated for 50 events. The results showed the hotter Fe line emissions have strong correlation with soft X-ray data in many cases. However, our statistical study revealed that EUV flare peak flux of Fe XV, Fe XVI and He II lines have weak correlation with soft X-ray peak flux. In EUV line light curves, there was time difference in peak time, however the tendency to reach the peak in order from the hotter line to cooler line was not so clear. These results indicate that the temporal evolution of EUV emission can be roughly explained by soft X-ray data. However, the time changes of temperature and density distributions in the flare loop must be needed for accurate reproduction. Moreover, we compared the geometrical features of solar flares observed by the Atmospheric Imaging Assembly on board the SDO with the fundamental flare parameters for 32 events. The ribbon distance strongly correlated with both soft X-ray flare rise and decay times. This results indicate that the geometrical feature is essential parameter for predicting flare emission duration. Title: Nowcast of an EUV dynamic spectrum during solar flares Authors: Kawai, Toshiki; Imada, Shinsuke; Nishimoto, Shohei; Watanabe, Kyoko; Kawate, Tomoko Bibcode: 2020JASTP.20505302K Altcode: 2020arXiv200506099K In addition to X-rays, extreme ultraviolet (EUV) rays radiated from solar flares can cause serious problems, such as communication failures and satellite drag. Therefore, methods for forecasting EUV dynamic spectra during flares are urgently required. Recently, however, owing to the lack of instruments, EUV dynamic spectra have rarely been observed. Hence, we develop a new method that converts the soft X-ray light curve observed during large flare events into an EUV dynamic spectrum by using the Solar Dynamics Observatory/Atmospheric Imaging Assembly images, a numerical simulation, and atomic database. The simulation provides the solution for a coronal loop that is heated by a strong flare, and the atomic database calculates its dynamic spectrum, including X-ray and EUV irradiances. The coefficients needed for the conversion can be calculated by comparing the observed soft X-ray light curve with that of the simulation. We apply our new method to three flares that occurred in the active region 12673 on September 06, 2017. The results show similarities to those of the Flare Irradiance Spectral Model, and reconstruct some of the EUV peaks observed by the EUV Variability Experiment onboard the Solar Dynamics Observatory. Title: Intrusion of Magnetic Peninsula toward the Neighboring Opposite-polarity Region That Triggers the Largest Solar Flare in Solar Cycle 24 Authors: Bamba, Yumi; Inoue, Satoshi; Imada, Shinsuke Bibcode: 2020ApJ...894...29B Altcode: 2020arXiv200500688B The largest X9.3 solar flare in solar cycle 24 and the preceding X2.2 flare occurred on 2017 September 6, in the solar active region NOAA 12673. This study aims to understand the onset mechanism of these flares via analysis of multiple observational data sets from the Hinode and Solar Dynamics Observatory and results from a nonlinear force-free field extrapolation. The most noticeable feature is the intrusion of a major negative-polarity region, appearing similar to a peninsula, oriented northwest into a neighboring opposite-polarity region. We also observe proxies of magnetic reconnection related to the intrusion of the negative peninsula: rapid changes of the magnetic field around the intruding negative peninsula; precursor brightening at the tip of the negative peninsula, including a cusp-shaped brightening that shows a transient but significant downflow (∼100 km s-1) at a leg of the cusp; a dark tube-like structure that appears to be a magnetic flux rope that erupted with the X9.3 flare; and coronal brightening along the dark tube-like structure that appears to represent the electric current generated under the flux rope. Based on these observational features, we propose that (1) the intrusion of the negative peninsula was critical in promoting the push-mode magnetic reconnection that forms and grows a twisted magnetic flux rope that erupted with the X2.2 flare, and (2) the continuing intrusion progressing even beyond the X2.2 flare is further promoted to disrupt the equilibrium that leads the reinforcement of the magnetic flux rope that erupted with the X9.3 flare. Title: A Solar Magnetic-fan Flaring Arch Heated by Nonthermal Particles and Hot Plasma from an X-Ray Jet Eruption Authors: Lee, Kyoung-Sun; Hara, Hirohisa; Watanabe, Kyoko; Joshi, Anand D.; Brooks, David H.; Imada, Shinsuke; Prasad, Avijeet; Dang, Phillip; Shimizu, Toshifumi; Savage, Sabrina L.; Moore, Ronald; Panesar, Navdeep K.; Reep, Jeffrey W. Bibcode: 2020ApJ...895...42L Altcode: 2020arXiv200509875L We have investigated an M1.3 limb flare, which develops as a magnetic loop/arch that fans out from an X-ray jet. Using Hinode/EIS, we found that the temperature increases with height to a value of over 107 K at the loop top during the flare. The measured Doppler velocity (redshifts of 100-500 km s-1) and the nonthermal velocity (≥100 km s-1) from Fe XXIV also increase with loop height. The electron density increases from 0.3 × 109 cm-3 early in the flare rise to 1.3 × 109 cm-3 after the flare peak. The 3D structure of the loop derived with Solar TErrestrial RElations Observatory/EUV Imager indicates that the strong redshift in the loop-top region is due to upflowing plasma originating from the jet. Both hard X-ray and soft X-ray emission from the Reuven Ramaty High Energy Solar Spectroscopic Imager were only seen as footpoint brightenings during the impulsive phase of the flare, then, soft X-ray emission moved to the loop top in the decay phase. Based on the temperature and density measurements and theoretical cooling models, the temperature evolution of the flare arch is consistent with impulsive heating during the jet eruption followed by conductive cooling via evaporation and minor prolonged heating in the top of the fan loop. Investigating the magnetic field topology and squashing factor map from Solar Dynamics Observatory/HMI, we conclude that the observed magnetic-fan flaring arch is mostly heated from low atmospheric reconnection accompanying the jet ejection, instead of from reconnection above the arch as expected in the standard flare model. Title: White-light Emission and Chromospheric Response by an X1.8-class Flare on 2012 October 23 Authors: Watanabe, Kyoko; Imada, Shinsuke Bibcode: 2020ApJ...891...88W Altcode: On 2012 October 23, a strong white-light emission, associated with an X1.8-class flare, was observed by the Solar Optical Telescope on board the Hinode satellite. White-light kernels were clearly observed along the Ca II H ribbons. RHESSI also observed hard X-ray emissions that were almost located on the white-light kernels. The total energy of the white-light emission was ∼ 1027-28 erg, s-1 and the total energy of the accelerated electrons was almost of the same order when we used 40 keV as the lower energy cutoff. The white-light emission appears to have originated from nonthermal electrons in these energies. Moreover, the EUV imaging spectrometer on board the Hinode satellite performed a raster scan over this flaring active region and the flare occurred during the scan. Over the white-light kernels, we observed redshifts of a few tens of km s-1 in Fe XII. It appears that these EUV responses originated from some accelerated electrons due to the solar flare and they are considered to be the source of the white-light emission. In fact, the electron density of the white-light kernels was less than 1012 cm-3, which is sufficiently low for nonthermal electrons to penetrate into the photosphere. Title: Thaddäus Derfflinger's Sunspot Observations during 1802-1824: A Primary Reference to Understand the Dalton Minimum Authors: Hayakawa, Hisashi; Besser, Bruno P.; Iju, Tomoya; Arlt, Rainer; Uneme, Shoma; Imada, Shinsuke; Bourdin, Philippe-A.; Kraml, Amand Bibcode: 2020ApJ...890...98H Altcode: 2020arXiv200102367H As we are heading toward the next solar cycle, presumably with a relatively small amplitude, it is of significant interest to reconstruct and describe the past secular minima on the basis of actual observations at the time. The Dalton Minimum is often considered one of the secular minima captured in the coverage of telescopic observations. Nevertheless, the reconstructions of the sunspot group number vary significantly, and the existing butterfly diagrams have a large data gap during the period. This is partially because most long-term observations at that time have remained unexplored in historical archives. Therefore, to improve our understanding on the Dalton Minimum, we have located two series of Thaddäus Derfflinger's observational records spanning 1802-1824 (a summary manuscript and logbooks), as well as his Brander's 5.5 feet azimuthal quadrant preserved in the Kremsmünster Observatory. We have revised the existing Derfflinger's sunspot group number with Waldmeier classification, and eliminated all the existing "spotless days" to remove contaminations from solar elevation observations. We have reconstructed the butterfly diagram on the basis of his observations and illustrated sunspot distributions in both solar hemispheres. Our article aims to revise the trend of Derfflinger's sunspot group number and to bridge a data gap of the existing butterfly diagrams around the Dalton Minimum. Our results confirm that the Dalton Minimum is significantly different from the Maunder Minimum, both in terms of cycle amplitudes and sunspot distributions. Therefore, the Dalton Minimum is more likely a secular minimum in the long-term solar activity, while further investigations for the observations at that time are required. Title: Statistical and Observational Research of Solar Flare EUV Spectra and Geometrical Features for Predicting Total Flare Emission Spectra Authors: Nishimoto, S.; Watanabe, K.; Imada, S.; Kawai, T.; Kawate, T.; Lee, K. S. Bibcode: 2019AGUFMSH34A..04N Altcode: We are performing statistical analysis of observed flare emissions for making the total flare emission spectra prediction model. The Flare Irradiance Spectral Model (FISM) (Chamberlin et al. 2006, 2007, 2008) is one of the total flare spectra prediction model which is currently most widely used. However, since FISM is empirical model, there are problems such as the uncertain physical process. In order to solve FISM's problems, we are trying to make new prediction model of total flare spectra. For this purpose, we searched for which flare parameter affect to the flare emission. We used the soft X-ray data (intensity & duration) as fundamental parameter, and compared with EUV data observed by SDO/EVE MEGS-A statistically. We have 53 events which were MEGS-A observed with >M3 class flare, and especially analyzed for 6 EUV lines. We found the soft X-ray peak intensity was well correlated with EUV line peak intensity. The EUV rising time also well correlated with soft X-ray rising time, and hotter lines peaked earlier than cooler lines. Moreover, we also searched for the relationship with geometrical features (ribbon length & width) of solar flare observed by SDO/AIA 1600 Å for 32 events. We found the ribbon distance is related to the rising time of soft X-ray, and the ribbon length is related to the decay time of soft X-ray. From these results, we can say that the Fe line emissions can be explain by the soft X-ray emissions. Moreover, the soft X-ray light curve also can be estimated by the flare loop length. Then, we performed numerical simulations (Imada et al., 2015) using observational parameters obtained above results. In this paper, we show some results of numerical simulations, and will discuss which parameters strongly control the solar flare EUV emission spectra by comparing with observed data. Title: The International Heliophysics Data Environment Alliance and its possible role in ISWAT Authors: Masson, A.; Roberts, D. A.; Fung, S. F.; Miyoshi, Y.; Imada, S.; Malapert, J. C.; Arviset, C. Bibcode: 2019AGUFMSM31C3549M Altcode: The IHDEA was formed as a result of the first International Heliophysics Data Environment (IHDE) meeting held at the European Space and Astronomy Centre (ESAC), Madrid, Spain, on October 17-18, 2018. Meeting attendees representing NASA, ESA, JAXA, and CNES have all agreed that increasing collaboration and coordination through the use of standard formats (for both data and metadata) and community-based data tools are critical for enabling interoperability of data systems and services while improving sharing of space-based, ground-based, and model-based heliophysics data sets. The newly created International Heliophysics Data Environment Alliance (IHDEA) is a collaborative organization whose goal is to guide the development of a data environment in which the international heliophysics and space weather research community can seamlessly find, access, and use all electronically accessible, heliophysics relevant data sets. The specific mission of the IHDEA is to facilitate global access to, and exchange of, high quality scientific data products managed across international boundaries. This will be achieved by adhering to, and promote the use of, a set of governing data standards, data exchange protocols, visualization and data analysis tools. The role of the IHDEA is to serve as the focal point to engage the heliophysics data centres and the scientific community, foster communication, and identify the standards and services that will best serve the heliophysics and space weather science needs. Practical examples will be provided, illustrating the mutual interest to foster collaboration between key heliophysics data providers. How IHDEA could support ISWAT information architecture will be discussed and in particular how IHDEA could facilitate information sharing and interconnection between ISWAT teams and Clusters. Title: Hybrid Simulation for the Solar Modulation of the Galactic Cosmic Rays During Recent Solar Cycle Authors: Miyake, S.; Matsumoto, T.; Kataoka, R.; Sato, T.; Shiota, D.; Miyahara, H.; Imada, S.; Ueno, H. Bibcode: 2019AGUFMSM31E3197M Altcode: In the current and next weak solar cycles, we expect higher flux of galactic cosmic rays (GCRs) than that in the previous solar cycles because of the decreasing trend of the solar activity. It is important to quantitatively evaluate the high flux of galactic cosmic rays because it leads to the increase in the radiation exposure of aircrews and the increasing rates of single event upset events at spacecraft. However, reliable prediction of the increasing galactic cosmic rays in upcoming weak solar cycles is a challenges topic in the field of space weather forecast. Grand Minimum 7 (Gm7) is a new project for understanding of heliospheric environments during extremely weak solar cycle, such as past grand minima and current solar cycle. The purposes of Gm7 consists of revealing fundamental structure of the solar wind during extremely weak solar cycle, explaining a mechanism of unique solar modulation of the GCRs [1], and clarifying extreme space weather conditions on the resultant radiation exposure [2]. In order to achieve these objectives, we have developed a hybrid simulation model for the solar modulation of the GCRs in such a weak solar conditions, which solves the stochastic differential equations of energetic particles in the MHD solar wind resolved by adaptive mesh refinement technique [3]. In this presentation, we will show a first result of our hybrid simulation for the solar modulation of the GCRs during recent solar cycle.

[1] Kataoka, R., H. Miyahara, and F. Steinhilber, Space Weather, 10, S11001, 2012.

[2] Miyake, S., R. Kataoka, and T. Sato, Space Weather, 15(4), 589-605, 2017.

[3] Matsumoto, T., D. Shiota, R. Kataoka, H. Miyahara, and S. Miyake, Journal of Physics: Conference Series, 1225, 012008, 2019. Title: Estimation of temporal evolution of coronal hole by surface flux transport model and potential field source surface extrapolation method Authors: Watanabe, Y.; Imada, S.; Iijima, H.; Shiota, D.; Miyoshi, Y. Bibcode: 2019AGUFMSH43E3387W Altcode: In this study, we will estimate the temporal evolution of coronal holes by the surface flux transport (SFT) model and the potential field source surface (PFSS) extrapolation method. Estimating the temporal evolution of coronal hole, especially low latitude coronal hole, is crucial for space weather study. So far, we have developed the SFT model calculation to predict the next solar cycle activity and construct the forecast scheme. The possible relationship between the polar magnetic fields in the solar minimum and the solar activity in the maximum of the next cycle has been intensively discussed. Iijima et al. (2017) calculated the polar magnetic field at the solar minimum with the SFT model and concluded that the polar magnetic field of the next cycle is weaker than the current solar cycle. This is because polar magnetic fields are well reproduced by the SFT model. On the other hand, it is not clear whether the middle latitude magnetic fields can be well reproduced or not by the SFT model calculation. The middle latitude magnetic fields estimation is crucial for estimating the temporal evolution of coronal hole. With regard to the September 2017 X9.3 flared active region (NOAA12673), we focused on the transport of the magnetic field and the associated time evolutions in the polar coronal holes and open field lines. We compare the temporal evolution of the solar surface magnetic field by the SFT model calculations and observations. Further, we also calculated a three-dimensional coronal magnetic field using the PFSS extrapolation method with the calculated surface magnetic field distribution as a boundary condition and traced the open magnetic field lines derived from the foot point of the coronal hole. Although with the case where coronal holes are generated for the active region that appeared behind the Sun, we estimated whether we can predict coronal holes by comparing the coronal hole temporal evolution estimated by the SFT/PFSS model and AIA observation. Title: Prediction of Extreme Ultraviolet Dynamic Spectrum during Large Flare using Convolutional Neural Network Authors: Kawai, T.; Imada, S.; Nishimoto, S.; Watanabe, K.; Kawate, T. Bibcode: 2019AGUFMSH31D3337K Altcode: To forecast the influences of large flares on the earth, it is important to predict the time series of Extreme Ultraviolet (EUV) spectrum during flares. This is because an enhancement of EUVs can increase the density of the upper atmosphere and it can crash satellites in the low earth orbit by atmospheric drag forces. Therefore, the development of methods to nowcast/forecast EUV dynamic spectra is required. We have developed two methods. The first one is to nowcast the EUV spectrum by using 1D hydrodynamic simulation and CHIANTI atomic database. We calculate the light curve of GOES/XRS-B when a flare occurs in the simulation. We convert it to observed one by stacking it with matching these peaks. The EUV dynamic spectrum can be calculated by converting it as same as XRS-B. The another one is to forecast the EUV spectrum by using a Convolutional Neural Network (CNN) and 1D hydrodynamic simulation. We train a CNN to predict GOES/XRS-B light curves during flares as a response to the input of the past EUV maps and magnetograms observed by SDO/AIA. After that, we adjust the flare parameters in the simulation such as heating rate and duration to reconstruct predicted GOES/XRS-B light curves well. We applied these methods to M- and X-class flares occurred between 8:00 - 14:00 UT on 6 September 2017. We evaluate the accuracy of the prediction by comparing observed and predicted GOES/XRS-A light curves and total irradiance of SDO/AIA EUV maps. Title: Achievements of Hinode in the first eleven years Authors: Hinode Review Team; Al-Janabi, Khalid; Antolin, Patrick; Baker, Deborah; Bellot Rubio, Luis R.; Bradley, Louisa; Brooks, David H.; Centeno, Rebecca; Culhane, J. Leonard; Del Zanna, Giulio; Doschek, George A.; Fletcher, Lyndsay; Hara, Hirohisa; Harra, Louise K.; Hillier, Andrew S.; Imada, Shinsuke; Klimchuk, James A.; Mariska, John T.; Pereira, Tiago M. D.; Reeves, Katharine K.; Sakao, Taro; Sakurai, Takashi; Shimizu, Toshifumi; Shimojo, Masumi; Shiota, Daikou; Solanki, Sami K.; Sterling, Alphonse C.; Su, Yingna; Suematsu, Yoshinori; Tarbell, Theodore D.; Tiwari, Sanjiv K.; Toriumi, Shin; Ugarte-Urra, Ignacio; Warren, Harry P.; Watanabe, Tetsuya; Young, Peter R. Bibcode: 2019PASJ...71R...1H Altcode: Hinode is Japan's third solar mission following Hinotori (1981-1982) and Yohkoh (1991-2001): it was launched on 2006 September 22 and is in operation currently. Hinode carries three instruments: the Solar Optical Telescope, the X-Ray Telescope, and the EUV Imaging Spectrometer. These instruments were built under international collaboration with the National Aeronautics and Space Administration and the UK Science and Technology Facilities Council, and its operation has been contributed to by the European Space Agency and the Norwegian Space Center. After describing the satellite operations and giving a performance evaluation of the three instruments, reviews are presented on major scientific discoveries by Hinode in the first eleven years (one solar cycle long) of its operation. This review article concludes with future prospects for solar physics research based on the achievements of Hinode. Title: Effect of Morphological Asymmetry between Leading and Following Sunspots on the Prediction of Solar Cycle Activity Authors: Iijima, H.; Hotta, H.; Imada, S. Bibcode: 2019ApJ...883...24I Altcode: 2019arXiv190804474I The morphological asymmetry of leading and following sunspots is a well-known characteristic of the solar surface. In the context of the large-scale evolution of the surface magnetic field, the asymmetry has been assumed to have only a negligible effect. Using the surface flux transport (SFT) model, we show that the morphological asymmetry of leading and following sunspots has a significant impact on the evolution of the large-scale magnetic field on the solar surface. By evaluating the effect of the morphological asymmetry of each bipolar magnetic region (BMR), we observe that the introduction of asymmetry to the BMR model significantly reduces the contribution to the polar magnetic field, especially for large and high-latitude BMRs. Strongly asymmetric BMRs can even reverse regular polar field formation. The SFT simulations based on the observed sunspot record show that the introduction of morphological asymmetry reduces the root-mean-square difference from the observed axial dipole strength by 30%-40%. These results indicate that the morphological asymmetry of leading and following sunspots has a significant effect on the solar cycle prediction. Title: A Transit of Venus Possibly Misinterpreted as an Unaided-Eye Sunspot Observation in China on 9 December 1874 Authors: Hayakawa, Hisashi; Sôma, Mitsuru; Tanikawa, Kiyotaka; Willis, David M.; Wild, Matthew N.; Macdonald, Lee T.; Imada, Shinsuke; Hattori, Kentaro; Richard Stephenson, F. Bibcode: 2019SoPh..294..119H Altcode: 2019arXiv190802452H Large sunspots can be observed with the unaided eye under suitable atmospheric seeing conditions. Such observations are of particular value because the frequency of their appearance provides an approximate indication of the prevailing level of solar activity. Unaided-eye sunspot observations can be traced back well before the start of telescopic observations of the Sun, especially in the East Asian historical records. It is therefore important to compare more modern, unaided-eye sunspot observations with the results of telescopic sunspot observations, to gain a better understanding of the nature of the unaided-eye sunspot records. A previous comparison of Chinese unaided-eye sunspot records and Greenwich photo-heliographic results between 1874 and 1918 indicated that a few of the unaided-eye observations were apparently not supported by direct photographic evidence of at least one sunspot with a large area. This article reveals that one of such Chinese unaided-eye observations had possibly captured the transit of Venus on 9 December 1874. The Chinese sunspot records on this date are compared with Western sunspot observations on the same day. It is concluded that sunspots on the solar disk were quite small and the transit of Venus was probably misinterpreted as a sunspot (black spot) by the Chinese local intellectuals. This case indicates that sunspots or comparable "obscuring" objects with an area as large as 1000 millionths of the solar disk could reasonably have been seen with the unaided eye under suitable seeing conditions. It also confirms the visibility of sunspots near the solar limb with the unaided eye. This study provides an explanation of the apparent discrepancy between the Chinese unaided-eye sunspot observation on 9 December 1874 and the Western sunspot observations using telescopes, as well as a basis for further discussion on the negative pairs in 1900 and 1911, apparently without sufficiently large area. Title: Development of Solar-C_EUVST structural design Authors: Suematsu, Yoshinori; Shimizu, Toshifumi; Hara, Hirohisa; Katsukawa, Yukio; Kawate, Tomoko; Ichimoto, Kiyoshi; Imada, Shinsuke Bibcode: 2019SPIE11118E..1OS Altcode: The Solar-C_EUVST is a mission designed to provide high-quality solar spectroscopic data covering a wide temperature range of the chromosphere to flaring corona. To fulfill a high throughput requirement, the instrument consists of only two optical components; a 28-cm primary mirror and a segmented toroidal grating which have high reflective coatings in EUV-UV range. We present a mission payload structural design which accommodates long focal length optical components and a launcher condition/launch environment (JAXA Epsilon). We also present a mechanical design of primary mirror assembly which enables slit-scan observations, an image stabilizing tip-tilt control, and a focus adjustment on orbit, together with an optomechanical design of the primary mirror and its supporting system which gives optically tolerant wavefront error against a large temperature increase due to an absorption of visible and IR lights. Title: Concept study of Solar-C_EUVST optical design Authors: Kawate, Tomoko; Shimizu, Toshifumi; Imada, Shinsuke; Tsuzuki, Toshihiro; Katsukawa, Yukio; Hara, Hirohisa; Suematsu, Yoshinori; Ichimoto, Kiyoshi; Warren, Harry; Teriaca, Luca; Korendyke, Clarence M.; Brown, Charles Bibcode: 2019SPIE11118E..1NK Altcode: The main characteristics of Solar-C_EUVST are the high temporal and high spatial resolutions over a wide temperature coverage. In order to realize the instrument for meeting these scientific requirements under size constraints given by the JAXA Epsilon vehicle, we examined four-dimensional optical parameter space of possible solutions of geometrical optical parameters such as mirror diameter, focal length, grating magnification, and so on. As a result, we have identified the solution space that meets the EUVST science objectives and rocket envelope requirements. A single solution was selected and used to define the initial optical parameters for the concept study of the baseline architecture for defining the mission concept. For this solution, we optimized the grating and geometrical parameters by ray tracing of the Zemax software. Consequently, we found an optics system that fulfills the requirement for a 0.4" angular resolution over a field of view of 100" (including margins) covering spectral ranges of 170-215, 463-542, 557-637, 690-850, 925-1085, and 1115-1275 A. This design achieves an effective area 10 times larger than the Extreme-ultraviolet Imaging Spectrometer onboard the Hinode satellite, and will provide seamless observations of 4.2-7.2 log(K) plasmas for the first time. Tolerance analyses were performed based on the optical design, and the moving range and step resolution of focus mechanisms were identified. In the presentation, we describe the derivation of the solution space, optimization of the optical parameters, and show the results of ray tracing and tolerance analyses. Title: The Solar-C_EUVST mission Authors: Shimizu, Toshifumi; Imada, Shinsuke; Kawate, Tomoko; Ichimoto, Kiyoshi; Suematsu, Yoshinori; Hara, Hirohisa; Katsukawa, Yukio; Kubo, Masahito; Toriumi, Shin; Watanabe, Tetsuya; Yokoyama, Takaaki; Korendyke, Clarence M.; Warren, Harry P.; Tarbell, Ted; De Pontieu, Bart; Teriaca, Luca; Schühle, Udo H.; Solanki, Sami; Harra, Louise K.; Matthews, Sarah; Fludra, A.; Auchère, F.; Andretta, V.; Naletto, G.; Zhukov, A. Bibcode: 2019SPIE11118E..07S Altcode: Solar-C EUVST (EUV High-Throughput Spectroscopic Telescope) is a solar physics mission concept that was selected as a candidate for JAXA competitive M-class missions in July 2018. The onboard science instrument, EUVST, is an EUV spectrometer with slit-jaw imaging system that will simultaneously observe the solar atmosphere from the photosphere/chromosphere up to the corona with seamless temperature coverage, high spatial resolution, and high throughput for the first time. The mission is designed to provide a conclusive answer to the most fundamental questions in solar physics: how fundamental processes lead to the formation of the solar atmosphere and the solar wind, and how the solar atmosphere becomes unstable, releasing the energy that drives solar flares and eruptions. The entire instrument structure and the primary mirror assembly with scanning and tip-tilt fine pointing capability for the EUVST are being developed in Japan, with spectrograph and slit-jaw imaging hardware and science contributions from US and European countries. The mission will be launched and installed in a sun-synchronous polar orbit by a JAXA Epsilon vehicle in 2025. ISAS/JAXA coordinates the conceptual study activities during the current mission definition phase in collaboration with NAOJ and other universities. The team is currently working towards the JAXA final down-selection expected at the end of 2019, with strong support from US and European colleagues. The paper provides an overall description of the mission concept, key technologies, and the latest status. Title: Structure and dynamics of the hot flaring loop-top source observed by Hinode, SDO, RHESSI, and STEREO Authors: Lee, Kyoung-Sun; Hara, Hirohisa; Watanabe, Kyoko; Joshi, Anand D.; Imada, Shinsuke; Brooks, David H.; Dang, Phillip; Shimizu, Toshifumi; Savage, Sabrina Bibcode: 2019AAS...23421605L Altcode: We have investigated an M1.3 flare on 2014 January 13 around 21:48 UT observed at the west limb using the Hinode, SDO, RHESSI, and STEREO. Especially, the Hinode/EIS scanned the flaring loop covering the loop-top region over the limb, which is a good target to investigate the dynamics of the flaring loop with their height. Using the multi-wavelength observations from the Hinode/EIS and SDO/AIA, we found a very hot emission above the loop-top observed in Fe XXIV and 131Å channel. Measuring the intensity, Doppler velocity and line width for the flaring loop, we found that hot emission observed at the cusp-like shape of the loop-top region which shows strong redshift about 500 km s-1 in Doppler velocity and strong enhancement of the non-thermal velocity (line width enhancement) larger than 100 km s-1. Combining with the STEREO observation, we have examined the 3D structure with loop tilt angle and have investigated the velocity distribution of the loop-top region. With the loop tilt angle, we could identify the strong redshift at the loop-top region may indicate an up-flow along the loop-top region. From RHESSI hard X-ray (HXR), and soft X-ray (SXR) emission, we found that the footpoint brightening region at the beginning of the flare has a both HXR (25-50 keV) and SXR (12-25 keV) emission in which imply that the region has non-thermal emission or accelerated particles. Then, within 10 minutes the soft X-ray (SXR) emission observed near the cusp shape region at loop top. The temporal variation of the HXR and SXR emissions and the Doppler velocity variation of the hot plasma component at the loop-top imply that the strong flow in a hot component near loop-top could be the evaporation flows which detected at the corona along the tilted loop. Moreover, The temporal evolution of the temperature observed by SDO/AIA and Hinode/EIS also shows the cooling process of the flare plasma which is consistent with the impulsively heated flare model. Title: Velocity Structure and Temperature Dependence of an Extreme-Ultraviolet Jet Observed by Hinode Authors: Kawai, T.; Kanda, N.; Imada, S. Bibcode: 2019SoPh..294...74K Altcode: 2019arXiv190410271K The acceleration mechanism of EUV and X-ray jets is still unclear. In general, there are two candidates for the mechanism. One is magnetic reconnection, and the other is chromospheric evaporation. We observed a relatively compact X-ray jet that occurred between 10:50 - 11:10 UT on 18 February 2011 by using the Solar Dynamics Observatory/Atmospheric Imaging Assembly, and the X-ray Telescope, Solar Optical Telescope, and EUV Imaging Spectrometer onboard Hinode. Our results are as follows: i) The EUV and X-ray observations show the general characteristics of X-ray jets, such as an arcade straddling a polarity inversion line, a jet bright point shown at one leg of the arcade, and a spire above the arcade. ii) The multi-wavelength observations and Ca II H line image show the existence of a low-temperature (≈ 10 000 K) plasma (i.e., filament) at the center of the jet. iii) In the magnetogram and Ca II H line image, the filament exists over the polarity inversion line and arcade is also straddling it. In addition, magnetic cancellation occurs around the jet a few hours before and after the jet is observed. iv) The temperature distribution of the accelerated plasma, which was estimated from Doppler velocity maps, the calculated differential emission measure, and synthetic spectra show that there is no clear dependence between the plasma velocity and its temperature. For our third result, observations indicate that magnetic cancellation is probably related to the occurrence of the jet and filament formation. This suggests that the trigger of the jet is magnetic cancellation rather than flux emergence. The fourth result indicates that plasma acceleration accompanied by an X-ray jet seems to be caused by magnetic reconnection rather than chromospheric evaporation. Title: Revisiting Kunitomo's Sunspot Drawings During 1835 - 1836 in Japan Authors: Fujiyama, Masashi; Hayakawa, Hisashi; Iju, Tomoya; Kawai, Toshiki; Toriumi, Shin; Otsuji, Kenichi; Kondo, Katsuya; Watanabe, Yusaku; Nozawa, Satoshi; Imada, Shinsuke Bibcode: 2019SoPh..294...43F Altcode: 2019arXiv190303092F We revisit the sunspot drawings made by the Japanese astronomer Kunitomo Toubei during 1835 - 1836 and recount the sunspot group number for each image. There are two series of drawings, preliminary (P , containing 17 days with observations) and summary (S , covering 156 days with observations), all made using brush and ink. S is a compilation of drawings for the period from February 1835, to March 1836. Presently, the P drawings are available only for one month, September 1835; those of other periods have presumably been lost. Another drawing (I ) lets us recover the raw group count (RGC) for 25 September 1836, on which the RGC has not been registered in the existing catalogs. We also revise the RGCs from P and S using the Zürich classification and determine that Kunitomo's results tend to yield smaller RGCs than those of other contemporary observers. In addition, we find that Kunitomo's RGCs and spot areas have a correlation (0.71) that is not very different from the contemporary observer Schwabe (0.82). Although Kunitomo's spot areas are much larger than those determined by Schwabe due to skill and instrument limitations, Kunitomo at least captured the growing trend of the spot activity in the early phase of Solar Cycle 8. We also determine the solar rotation axis to estimate the accurate position (latitude and longitude) of the sunspot groups in Kunitomo's drawings. Title: Semiconservative reduced speed of sound technique for low Mach number flows with large density variations Authors: Iijima, H.; Hotta, H.; Imada, S. Bibcode: 2019A&A...622A.157I Altcode: 2018arXiv181204135I Context. The reduced speed of sound technique (RSST) has been used for efficient simulation of low Mach number flows in solar and stellar convection zones. The basic RSST equations are hyperbolic and are suitable for parallel computation by domain decomposition. The application of RSST is limited to cases in which density perturbations are much smaller than the background density. In addition, nonconservative variables are required to be evolved using this method, which is not suitable in cases where discontinuities such as shock waves coexist in a single numerical domain.
Aims: In this study, we suggest a new semiconservative formulation of the RSST that can be applied to low Mach number flows with large density variations.
Methods: We derive the wave speed of the original and newly suggested methods to clarify that these methods can reduce the speed of sound without affecting the entropy wave. The equations are implemented using the finite volume method. Several numerical tests are carried out to verify the suggested methods.
Results: The analysis and numerical results show that the original RSST is not applicable when mass density variations are large. In contrast, the newly suggested methods are found to be efficient in such cases. We also suggest variants of the RSST that conserve momentum in the machine precision. The newly suggested variants are formulated as semiconservative equations, which reduce to the conservative form of the Euler equations when the speed of sound is not reduced. This property is advantageous when both high and low Mach number regions are included in the numerical domain.
Conclusions: The newly suggested forms of RSST can be applied to a wider range of low Mach number flows. Title: Effect of Magnetic Field Strength on Solar Differential Rotation and Meridional Circulation Authors: Imada, S.; Fujiyama, M. Bibcode: 2018ApJ...864L...5I Altcode: 2018arXiv180803005I We studied the solar surface flows (differential rotation and meridional circulation) using a magnetic element feature tracking technique by which the surface velocity is obtained using magnetic field data. We used the line-of-sight magnetograms obtained by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory from 2010 May 01 to 2017 August 16 (Carrington rotations 2096 to 2193) and tracked the magnetic element features every hour. Using our method, we estimated the differential rotation velocity profile. We found rotation velocities of ∼30 and -170 m s-1 at latitudes of 0° and 60° in the Carrington rotation frame, respectively. Our results are consistent with previous results obtained by other methods, such as direct Doppler, time-distance helioseismology, or cross-correlation analyses. We also estimated the meridional circulation velocity profile and found that it peaked at ∼12 m s-1 at a latitude of 45°, which is also consistent with previous results. The dependence of the surface flow velocity on the magnetic field strength was also studied. In our analysis, the magnetic elements with stronger and weaker magnetic fields largely represent the characteristics of the active region remnants and solar magnetic networks, respectively. We found that magnetic elements with a strong (weak) magnetic field show a faster (slower) rotation speed. On the other hand, magnetic elements with a strong (weak) magnetic field show slower (faster) meridional circulation velocity. These results might be related to the Sun’s internal dynamics. Title: Electron Power-Law Spectra in Solar and Space Plasmas Authors: Oka, M.; Birn, J.; Battaglia, M.; Chaston, C. C.; Hatch, S. M.; Livadiotis, G.; Imada, S.; Miyoshi, Y.; Kuhar, M.; Effenberger, F.; Eriksson, E.; Khotyaintsev, Y. V.; Retinò, A. Bibcode: 2018SSRv..214...82O Altcode: 2018arXiv180509278O Particles are accelerated to very high, non-thermal energies in solar and space plasma environments. While energy spectra of accelerated electrons often exhibit a power law, it remains unclear how electrons are accelerated to high energies and what processes determine the power-law index δ . Here, we review previous observations of the power-law index δ in a variety of different plasma environments with a particular focus on sub-relativistic electrons. It appears that in regions more closely related to magnetic reconnection (such as the `above-the-looptop' solar hard X-ray source and the plasma sheet in Earth's magnetotail), the spectra are typically soft (δ ≳4). This is in contrast to the typically hard spectra (δ ≲4) that are observed in coincidence with shocks. The difference implies that shocks are more efficient in producing a larger non-thermal fraction of electron energies when compared to magnetic reconnection. A caveat is that during active times in Earth's magnetotail, δ values seem spatially uniform in the plasma sheet, while power-law distributions still exist even in quiet times. The role of magnetotail reconnection in the electron power-law formation could therefore be confounded with these background conditions. Because different regions have been studied with different instrumentations and methodologies, we point out a need for more systematic and coordinated studies of power-law distributions for a better understanding of possible scaling laws in particle acceleration as well as their universality. Title: Sunspot drawings by Japanese official astronomers in 1749-1750 Authors: Hayakawa, Hisashi; Iwahashi, Kiyomi; Fujiyama, Masashi; Kawai, Toshiki; Toriumi, Shin; Hotta, Hideyuki; Iijima, Haruhisa; Imada, Shinsuke; Tamazawa, Harufumi; Shibata, Kazunari Bibcode: 2018PASJ...70...63H Altcode: 2018arXiv180408614H; 2018PASJ..tmp...87H Sunspot observations with telescopes in the 18th century were carried out in Japan as well as elsewhere. One of these sunspot observations is recorded in an account called Sansaizusetsu narabini Kansei irai Jissoku Zusetsu (Charts of Three Worlds and Diagrams of Actual Observations since Kansei Era). We have analyzed manuscripts of this account to show a total of 15 sunspot drawings during 1749-1750. These observations are considered to be carried out by contemporary official astronomers in Japan, with telescopes covered by zongurasus (< zonglas in Dutch, corresponding to "sunglass" in English). We counted their group number of sunspots to locate them in long-term solar activity and show that their observations were situated near the solar maximum in 1750. We also computed their locations and areas, while we have to admit differences of the variant manuscripts with one another. These observational records show the spread of sunspot observations not only in Europe, but also in Japan, and hence may contribute to crosscheck, or possibly to improve the known sunspot indices. Title: Science Objectives of the Solar-C_EUVST Authors: Imada, Shinsuke; Suematsu, Yoshinori Bibcode: 2018cosp...42E1542I Altcode: Solar-C EUVST (EUV High-Throughput Spectroscopic Telescope) is designed to comprehensively understand the energy and mass transfer from the solar surface to the solar corona and interplanetary space, and to investigate the elementary processes that take place universally in cosmic plasmas. The proposed mission is a fundamental step for answering how the plasma universe is created and evolves, and how the Sun influences the Earth and other planets in our solar system. The two primary science objectives for Solar-C EUVST are : I) Understand how fundamental processes lead to the formation of the solar atmosphere and the solar wind, II) Understand how the solar atmosphere becomes unstable, releasing the energy that drives solar flares and eruptions. Solar-C EUVST will, A) seamlessly observe all the temperature regimes of the solar atmosphere from the chromosphere to the corona at the same time, B) resolve elemental structures of the solar atmosphere with high spatial resolution and cadence to track their evolution, and C) obtain spectroscopic information on the dynamics of elementary processes taking place in the solar atmosphere. In this talk, we will first discuss the science target of the Solar-C EUVST, and discuss the science topic associated flare in detail. Photospheric motions lead to the accumulation of free magnetic energy in the corona. This system eventually becomes unstable, releasing the energy through magnetic reconnection. This process of energy conversion heats the plasma to high temperatures and drives coronal mass ejections (CMEs). By measuring the properties of multi-temperature flaring plasma, Solar-C EUVST will investigate why the reconnection is fast despite the high magnetic Reynolds number. It will also monitor the temporal evolution of solar active regions and identify the triggering mechanism for the flare and eruption. Therefore two important science objectives are defined for the flare physics. The first objective is "Understand the Fast Magnetic Reconnection Process". Magnetic reconnection is one of the fundamental processes for converting magnetic energy into the thermal and kinetic energy of the plasma. This process occurs much faster than is predicted by classical theory. Solar-C EUVST will observe the dynamics of magnetic structures to understand the mechanisms that lead to fast magnetic reconnection in partially or fully ionized plasmas. The second objective is "Identify the Signatures of Global Energy Buildup and the Local Triggering of the Flare and Eruption". Understanding the accumulation and release of free magnetic energy in the corona is a fundamental problem. Solar-C EUVST will perform long-term monitoring of active regions to identify the signatures of energy buildup and high-resolution observations to understand the triggers of energy release. Title: First Ten Years of Hinode Solar On-Orbit Observatory Authors: Shimizu, Toshifumi; Imada, Shinsuke; Kubo, Masahito Bibcode: 2018ASSL..449.....S Altcode: No abstract at ADS Title: The Origin of the Solar Wind Authors: Lee, Kyoung-Sun; Brooks, David H.; Imada, Shinsuke Bibcode: 2018ASSL..449...95L Altcode: No abstract at ADS Title: Thermal Non-equilibrium Plasma Observed by Hinode Authors: Imada, Shinsuke Bibcode: 2018ASSL..449..221I Altcode: No abstract at ADS Title: Statistical and observational research of solar flare for total spectra and geometrical features Authors: Nishimoto, S.; Watanabe, K.; Imada, S.; Kawate, T.; Lee, K. S. Bibcode: 2017AGUFMSH41A2749N Altcode: Impulsive energy release phenomena such as solar flares, sometimes affect to the solar-terrestrial environment. Usually, we use soft X-ray flux (GOES class) as the index of flare scale. However, the magnitude of effect to the solar-terrestrial environment is not proportional to that scale. To identify the relationship between solar flare phenomena and influence to the solar-terrestrial environment, we need to understand the full spectrum of solar flares. There is the solar flare irradiance model named the Flare Irradiance Spectral Model (FISM) (Chamberlin et al., 2006, 2007, 2008). The FISM can estimate solar flare spectra with high wavelength resolution. However, this model can not express the time evolution of emitted plasma during the solar flare, and has low accuracy on short wavelength that strongly effects and/or controls the total flare spectra. For the purpose of obtaining the time evolution of total solar flare spectra, we are performing statistical analysis of the electromagnetic data of solar flares. In this study, we select solar flare events larger than M-class from the Hinode flare catalogue (Watanabe et al., 2012). First, we focus on the EUV emission observed by the SDO/EVE. We examined the intensities and time evolutions of five EUV lines of 55 flare events. As a result, we found positive correlation between the "soft X-ray flux" and the "EUV peak flux" for all EVU lines. Moreover, we found that hot lines peaked earlier than cool lines of the EUV light curves. We also examined the hard X-ray data obtained by RHESSI. When we analyzed 163 events, we found good correlation between the "hard X-ray intensity" and the "soft X-ray flux". Because it seems that the geometrical features of solar flares effect to those time evolutions, we also looked into flare ribbons observed by SDO/AIA. We examined 21 flare events, and found positive correlation between the "GOES duration" and the "ribbon length". We also found positive correlation between the "ribbon length" and the "ribbon distance", however, there was no remarkable correlation of the "ribbon width". To understand physical process of flare emission, we performed numerical simulation (Imada et al., 2015), and compared with the observational flare model. We also discuss the flare numerical model which can be fitted to the observational flare model. Title: Investigation of the magnetic neutral line region with the frame of two-fluid equations: A possibility of anomalous resistivity inferred from MMS observations Authors: Kobayashi, Y.; Kitamura, N.; Ieda, A.; Yoshizumi, M.; Imada, S.; Tsugawa, Y.; Burch, J. L.; Russell, C. T.; Moore, T. E.; Giles, B. L.; Paterson, W.; Torbert, R. B.; Ergun, R.; Saito, Y.; Yokota, S.; Machida, S. Bibcode: 2017AGUFMSM13B2355K Altcode: Magnetic reconnection is a basic physical process by which energy of magnetic field is converted into the kinetic energy of plasmas. In recent years, MMS missionconsisting of four spacecraft has been conducted aiming at elucidating the physical mechanism of merging themagnetic fields in the vicinity of the magnetic neutral linethat exists in the central part of the structure. In this paper, we examine the magnetic field frozen-in relation near the magnetic neutral line as well as the causal relationship between electron and ion dynamics in the frame of two fluid equations.Theoretically, it is shown that electrons are frozen-in to the magnetic fields while ion's frozen-in relation is broken in the ion dissipation region. However, when we examined the observational data around 1307 UT on October 16, 2015 when MMS spacecraft passed through the vicinity of the magnetic neutral line [Burch et al., Science 2016] , it was confirmed that the frozen-ion relation was not established for electrons in the ion dissipation region. In addition, we found that intense wave electric fields in this region. From the spectral analysis of the waves, it turned out that their characteristic frequencies are the lower-hybrid and electron cyclotron frequencies.In the framework of the two-fluid equation, we can evaluate the values of each term of the equations of motion for both ions and electrons except for the collision term from MMS spacecraft data. Therefore, it is possible to obtain collision terms for both species. Since magnetospheric plasma is basically collisionless, it is considered that the collision term is due to anomalous resistivity associated with the excited waves . On the other hand, in the two-fluid equation system, the two vectors corresponding to the collision terms of ions and electrons have the same absolute value. Because the force exerted between the two is the internal force, they should face in the opposite direction. However, the vectors corresponding to the collision terms obtained by using the actual data did not satisfy such a condition. One of the possible reasons is that the momentum carried by the waves cannot be neglected. After careful examination, we conclude that the effect of the anomalous resistivity in the ion dissipation region acts to some degree that cannot be ignored in the equation of motion of the two-fluid system. Title: Non-thermal Power-Law Distributions in Solar and Space Plasmas Authors: Oka, M.; Battaglia, M.; Birn, J.; Chaston, C. C.; Effenberger, F.; Eriksson, E.; Fletcher, L.; Hatch, S.; Imada, S.; Khotyaintsev, Y. V.; Kuhar, M.; Livadiotis, G.; Miyoshi, Y.; Retino, A. Bibcode: 2017AGUFMSH51C2518O Altcode: Particles are accelerated to very high, non-thermal energies in solar and space plasma environments. While energy spectra of accelerated particles often exhibit a power-law and are characterized by the power-law index δ, it remains unclear how particles are accelerated to high energies and how δ is determined. Here, we review previous observations of the power-law index δ in a variety of different plasma environments with a particular focus on sub-relativistic electrons. It appears that in regions more closely related to magnetic reconnection (such as the "above-the-looptop" solar hard X-ray source and the plasma sheet in Earth's magnetotail), the spectra are typically soft (δ> 4). This is in contrast to the typically hard spectra (δ< 4) that are observed in coincidence with shocks. The difference implies that shocks are more efficient in producing a larger fraction of non-thermal electron energies than magnetic reconnection. A caveat is that during active times in Earth's magnetotail, δ values seem spatially uniform in the plasma sheet, while power-law distributions still exist even in quiet times. The role of magnetotail reconnection in the electron power-law formation could therefore be confounded with these background conditions. Because different regions have been studied with different instrumentations and methodologies, we point out a need for more systematic and coordinated studies of power-law distributions for a better understanding of possible scaling laws in particle acceleration as well as their universality. Title: Cosmic Ray Modulation and Radiation Dose of Aircrews During Possible Grand Minimum Authors: Miyake, S.; Kataoka, R.; Sato, T.; Imada, S.; Miyahara, H.; Shiota, D.; Matsumoto, T.; Ueno, H. Bibcode: 2017AGUFMSH53A2556M Altcode: The Sun is exhibiting low solar activity levels since the descending phase of the last solar cycle, and it is likely to be continued as well as in the case of the past grand solar minima. The cosmic-ray modulation, which is the variation of the galactic cosmic ray (GCR) spectrum caused by the heliospheric environmental change, is basically anti-correlated with the solar activity. In the recent weak solar cycle, we thus expect that the flux of GCRs is getting higher than that in the previous solar cycles, leading to the increase in the radiation exposure in the space and atmosphere. In order to quantitatively evaluate the possible solar modulation of GCRs and resultant radiation exposure at flight altitude, we have developed the time-dependent and three-dimensional model of the cosmic-ray modulation. Our model can give the flux of GCRs anywhere in the heliosphere by assuming the variation of the solar wind speed, the strength of the heliospheric magnetic field (HMF), and its tilt angle. We solve the gradient-curvature drift motion of GCRs in the HMF, and therefore reproduce the 22-year variation of the cosmic-ray modulation. We also calculate the neutron monitor counting rate and the radiation dose of aircrews at flight altitude, by the air-shower simulation performed by PHITS (Particle and Heavy Ion Transport code System). In our previous study [1], we calculated the radiation dose at a flight altitude during the coming solar cycle by assuming the variation of the solar wind speed and the strength of the HMF expressed by sinusoidal curve, and obtained that an annual radiation dose of aircrews in 5 years around the next solar minimum will be up to 19% higher than that at the last cycle. In this study, we predict the new model of the heliospheric environmental change on the basis of a prediction model for the sunspot number. The quantitative predictions of the cosmic-ray modulation and the radiation dose at a flight altitude during possible Grand Minimum considering the new model for the heliospheric environmental change will be presented at the meeting. [1] S. Miyake, R. Kataoka, and T. Sato, Space Weather, 15, 589-605, 2017. Title: Solar Surface Velocity in the Large Scale estimated by Magnetic Element Tracking Method Authors: Fujiyama, M.; Imada, S.; Iijima, H.; Machida, S. Bibcode: 2017AGUFMSH13A2474F Altcode: The 11years variation in the solar activity is one of the important sources of decadal variation in the solar-terrestrial environment. Therefore, predicting the solar cycle activity is crucial for the space weather. To build the prediction schemes for the next solar cycle is a key for the long-term space weather study. Recently, the relationship between polar magnetic field at the solar minimum and next solar cycle activity is intensively discussed. Nowadays, many people believe that the polar magnetic field at the solar minimum is one of the best predictor for the next solar cycle. To estimate polar magnetic field, Surface Flux Transport (SFT) model have been often used. On the other hand, SFT model needs several parameters, for example Meridional circulation, differential rotation, turbulent diffusion etc.. So far, those parameters have not been fully understood, and their uncertainties may affect the accuracy of the prediction. In this study, we try to discuss the parameters which are used in SFT model. We focus on two kinds of the solar surface motions, Differential rotation and Meridional circulation. First, we have developed Magnetic Element Tracking (MET) module, which is able to obtain the surface velocity by using the magnetic field data. We have used SOHO/MDI and SDO/HMI for the magnetic field data. By using MET, we study the solar surface motion over 2 cycle (nearly 24 years), and we found that the velocity variation is related to the active region belt. This result is consistent with [Hathaway et al., 2011]. Further, we apply our module to the Hinode/SOT data which spatial resolution is high. Because of its high resolution, we can discuss the surface motion close to the pole which has not been discussed enough. Further, we discuss the relationship between the surface motion and the magnetic field strength and the location of longitude. Title: Improvement of solar-cycle prediction: Plateau of solar axial dipole moment Authors: Iijima, H.; Hotta, H.; Imada, S.; Kusano, K.; Shiota, D. Bibcode: 2017A&A...607L...2I Altcode: 2017arXiv171006528I
Aims: We report the small temporal variation of the axial dipole moment near the solar minimum and its application to the solar-cycle prediction by the surface flux transport (SFT) model.
Methods: We measure the axial dipole moment using the photospheric synoptic magnetogram observed by the Wilcox Solar Observatory (WSO), the ESA/NASA Solar and Heliospheric Observatory Michelson Doppler Imager (MDI), and the NASA Solar Dynamics Observatory Helioseismic and Magnetic Imager (HMI). We also use the SFT model for the interpretation and prediction of the observed axial dipole moment.
Results: We find that the observed axial dipole moment becomes approximately constant during the period of several years before each cycle minimum, which we call the axial dipole moment plateau. The cross-equatorial magnetic flux transport is found to be small during the period, although a significant number of sunspots are still emerging. The results indicate that the newly emerged magnetic flux does not contribute to the build up of the axial dipole moment near the end of each cycle. This is confirmed by showing that the time variation of the observed axial dipole moment agrees well with that predicted by the SFT model without introducing new emergence of magnetic flux. These results allow us to predict the axial dipole moment at the Cycle 24/25 minimum using the SFT model without introducing new flux emergence. The predicted axial dipole moment at the Cycle 24/25 minimum is 60-80 percent of Cycle 23/24 minimum, which suggests the amplitude of Cycle 25 is even weaker than the current Cycle 24.
Conclusions: The plateau of the solar axial dipole moment is an important feature for the longer-term prediction of the solar cycle based on the SFT model. Title: Multi-Wavelength Spectroscopic Observations of a White Light Flare Produced Directly by Non-thermal Electrons Authors: Lee, Kyoung-Sun; Imada, Shinsuke; Watanabe, Kyoko; Bamba, Yumi; Brooks, David Bibcode: 2017SPD....4810806L Altcode: An X1.6 flare on 2014 October 22 was observed by multiple spectrometers in UV, EUV and X-ray (Hinode/EIS, IRIS, and RHESSI), and multi-wavelength imaging observations (SDO/AIA and HMI). We analyze a bright kernel that produces a white light (WL) flare with continuum enhancement and a hard X-ray (HXR) peak. Taking advantage of the spectroscopic observations of IRIS and Hinode/EIS, we measure the temporal variation of the plasma properties in the bright kernel in the chromosphere and corona. We find that explosive evaporation was observed when the WL emission occurred. The temporal correlation of the WL emission, HXR peak, and evaporation flows indicates that the WL emission was produced by accelerated electrons. We calculated the energy flux deposited by non-thermal electrons (observed by RHESSI) and compared it to the dissipated energy estimated from a chromospheric line (Mg II triplet) observed by IRIS. The deposited energy flux from the non-thermal electrons is about (3-7.7)x1010 erg cm-2 s-1 for a given low-energy cutoff of 30-40 keV, assuming the thick-target model. The energy flux estimated from the changes in temperature in the chromosphere measured using the Mg II subordinate line is about (4.6-6.7)×109 erg cm-2 s-1: ∼6%-22% of the deposited energy. This comparison of estimated energy fluxes implies that the continuum enhancement was directly produced by the non-thermal electrons. Title: Detection of Heating Processes in Coronal Loops by Soft X-ray Spectroscopy Authors: Kawate, Tomoko; Narukage, Noriyuki; Ishikawa, Shin-nosuke; Imada, Shinsuke Bibcode: 2017SPD....4810615K Altcode: Imaging and Spectroscopic observations in the soft X-ray band will open a new window of the heating/acceleration/transport processes in the solar corona. The soft X-ray spectrum between 0.5 and 10 keV consists of the electron thermal free-free continuum and hot coronal lines such as O VIII, Fe XVII, Mg XI, Si XVII. Intensity of free-free continuum emission is not affected by the population of ions, whereas line intensities especially from highly ionized species have a sensitivity of the timescale of ionization/recombination processes. Thus, spectroscopic observations of both continuum and line intensities have a capability of diagnostics of heating/cooling timescales. We perform a 1D hydrodynamic simulation coupled with the time-dependent ionization, and calculate continuum and line intensities under different heat input conditions in a coronal loop. We also examine the differential emission measure of the coronal loop from the time-integrated soft x-ray spectra. As a result, line intensity shows a departure from the ionization equilibrium and shows different responses depending on the frequency of the heat input. Solar soft X-ray spectroscopic imager will be mounted in the sounding rocket experiment of the Focusing Optics X-ray Solar Imager (FOXSI). This observation will deepen our understanding of heating processes to solve the “coronal heating problem”. Title: Predicting Solar Cycle 25 using Surface Flux Transport Model Authors: Imada, Shinsuke; Iijima, Haruhisa; Hotta, Hideyuki; Shiota, Daiko; Kusano, Kanya Bibcode: 2017SPD....4811106I Altcode: It is thought that the longer-term variations of the solar activity may affect the Earth’s climate. Therefore, predicting the next solar cycle is crucial for the forecast of the “solar-terrestrial environment”. To build prediction schemes for the next solar cycle is a key for the long-term space weather study. Recently, the relationship between polar magnetic field at the solar minimum and next solar activity is intensively discussed. Because we can determine the polar magnetic field at the solar minimum roughly 3 years before the next solar maximum, we may discuss the next solar cycle 3years before. Further, the longer term (~5 years) prediction might be achieved by estimating the polar magnetic field with the Surface Flux Transport (SFT) model. Now, we are developing a prediction scheme by SFT model as a part of the PSTEP (Project for Solar-Terrestrial Environment Prediction) and adapting to the Cycle 25 prediction. The predicted polar field strength of Cycle 24/25 minimum is several tens of percent smaller than Cycle 23/24 minimum. The result suggests that the amplitude of Cycle 25 is weaker than the current cycle. We also try to obtain the meridional flow, differential rotation, and turbulent diffusivity from recent modern observations (Hinode and Solar Dynamics Observatory). These parameters will be used in the SFT models to predict the polar magnetic fields strength at the solar minimum. In this presentation, we will explain the outline of our strategy to predict the next solar cycle and discuss the initial results for Cycle 25 prediction. Title: White paper of the "soft X-ray imaging spectroscopy" Authors: Narukage, Noriyuki; Ishikawa, Shin-nosuke; Kawate, Tomoko; Imada, Shinsuke; Sakao, Taro Bibcode: 2017arXiv170604536N Altcode: The solar corona is full of dynamic phenomena, e.g., solar flares, micro flares in active regions, jets in coronal holes and in the polar regions, X-ray bright points in quiet regions, etc. They are accompanied by interesting physical processes, namely, magnetic reconnection, particle acceleration, shocks, waves, flows, evaporation, heating, cooling, and so on. The understandings of these phenomena and processes have been progressing step-by-step with the evolution of the observation technology in EUV and X-rays from the space. But, there are fundamental questions remain unanswered, or haven't even addressed so far. Our scientific objective is to understand underlying physics of dynamic phenomena in the solar corona, covering some of the long-standing questions in solar physics such as particle acceleration in flares and coronal heating. In order to achieve these science objectives, we identify the imaging spectroscopy (the observations with spatial, temporal and energy resolutions) in the soft X-ray range (from ~0.5 keV to ~10 keV) is a powerful approach for the detection and analysis of energetic events. Title: Study on Precursor Activity of the X1.6 Flare in the Great AR 12192 with SDO, IRIS, and Hinode Authors: Bamba, Yumi; Lee, Kyoung-Sun; Imada, Shinsuke; Kusano, Kanya Bibcode: 2017ApJ...840..116B Altcode: 2017arXiv170405158B The physical properties and their contribution to the onset of a solar flare are still uncleare even though chromospheric brightening is considered a precursor phenomenon of a flare. Many studies suggested that photospheric magnetic field changes cause destabilization of large-scale coronal structure. We aim to understand how a small photospheric change contributes to a flare and to reveal how the intermediary chromosphere behaves in the precursor phase. We analyzed the precursor brightening of the X1.6 flare on 2014 October 22 in the AR 12192 using the Interface Region Imaging Spectrograph (IRIS) and Hinode/EUV Imaging Spectrometer (EIS) data. We investigated a localized jet with the strong precursor brightening, and compared the intensity, Doppler velocity, and line width in C II, Mg II k, and Si IV lines by IRIS and He II, Fe xii, and Fe xv lines by Hinode/EIS. We also analyzed the photospheric magnetic field and chromospheric/coronal structures using the Solar Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager and Atmospheric Imaging Assembly. We found a significant blueshift (∼100 km s-1), which is related to the strong precursor brightening over a characteristic magnetic field structure, and the blueshift was observed at all of the temperatures. This might indicate that the flow is accelerated by Lorentz force. Moreover, the large-scale coronal loop that connects the foot points of the flare ribbons was destabilized just after the precursor brightening with the blueshift. It suggests that magnetic reconnection locally occurred in the lower chromosphere and it triggered magnetic reconnection of the X1.6 flare in the corona. Title: IRIS, Hinode, SDO, and RHESSI Observations of a White Light Flare Produced Directly by Nonthermal Electrons Authors: Lee, Kyoung-Sun; Imada, Shinsuke; Watanabe, Kyoko; Bamba, Yumi; Brooks, David H. Bibcode: 2017ApJ...836..150L Altcode: 2017arXiv170106286L An X1.6 flare occurred in active region AR 12192 on 2014 October 22 at 14:02 UT and was observed by Hinode, IRIS, SDO, and RHESSI. We analyze a bright kernel that produces a white light (WL) flare with continuum enhancement and a hard X-ray (HXR) peak. Taking advantage of the spectroscopic observations of IRIS and Hinode/EIS, we measure the temporal variation of the plasma properties in the bright kernel in the chromosphere and corona. We find that explosive evaporation was observed when the WL emission occurred, even though the intensity enhancement in hotter lines is quite weak. The temporal correlation of the WL emission, HXR peak, and evaporation flows indicates that the WL emission was produced by accelerated electrons. To understand the WL emission process, we calculated the energy flux deposited by non-thermal electrons (observed by RHESSI) and compared it to the dissipated energy estimated from a chromospheric line (Mg II triplet) observed by IRIS. The deposited energy flux from the non-thermal electrons is about (3-7.7) × 1010 erg cm-2 s-1 for a given low-energy cutoff of 30-40 keV, assuming the thick-target model. The energy flux estimated from the changes in temperature in the chromosphere measured using the Mg II subordinate line is about (4.6-6.7) × 109 erg cm-2 s-1: ∼6%-22% of the deposited energy. This comparison of estimated energy fluxes implies that the continuum enhancement was directly produced by the non-thermal electrons. Title: UV/EUV High-Throughput Spectroscopic Telescope: A Next Generation Solar Physics Mission white paper Authors: Imada, S.; Shimizu, T.; Kawate, T.; Hara, H.; Watanabe, T. Bibcode: 2017arXiv170104972I Altcode: The origin of the activity in the solar corona is a long-standing problem in solar physics. Recent satellite observations, such as Hinode, Solar Dynamics Observatory (SDO), Interface Region Imaging Spectrograph (IRIS), show the detail characteristics of the solar atmosphere and try to reveal the energy transfer from the photosphere to the corona through the magnetic fields and its energy conversion by various processes. However, quantitative estimation of energy transfer along the magnetic field is not enough. There are mainly two reason why it is difficult to observe the energy transfer from photosphere to corona; 1) spatial resolution gap between photosphere (a few 0.1 arcsec) and corona (a few arcsec), 2) lack in temperature coverage. Furthermore, there is not enough observational knowledge of the physical parameters in the energy dissipation region. There are mainly three reason why it is difficult to observe in the vicinity of the energy dissipation region; 1) small spatial scale, 2) short time scale, 3) low emission. It is generally believed that the energy dissipation occurs in the very small scale and its duration is very short (10 second). Further, the density in the dissipation region might be very low. Therefore, the high spatial and temporal resolution UV/EUV spectroscopic observation with wide temperature coverage is crucial to estimate the energy transport from photosphere to corona quantitatively and diagnose the plasma dynamics in the vicinity of the energy dissipation region. Main Science Target for the telescope is quantitative estimation for the energy transfer from the photosphere to the corona, and clarification of the plasma dynamics in the vicinity of the energy dissipation region, where is the key region for coronal heating, solar wind acceleration, and/or solar flare, by the high spatial and temporal resolution UV/EUV spectroscopy. Title: Structures of the Hall magnetic field in the dayside magnetic reconnection inferred from Geotail data Authors: Tanaka, R.; Machida, S.; Uchino, H.; Imada, S.; Miyoshi, Y.; Seki, K.; Ieda, A.; Miyashita, Y.; Keika, K.; Saito, Y. Bibcode: 2016AGUFMSM13A2184T Altcode: Using Geotail data, we have investigated the magnetic reconnection structure at the dayside magnetopause. In the magnetotail, symmetric reconnection generally occurs, since upstream conditions are almost the same on the northern and southern sides. On the other hand, at the dayside magnetopause, asymmetric reconnection tends to occurs, since magnetospheric and solar wind plasmas have different conditions. In addition, while magnetotail reconnection has a quadrupole structure of the magnetic field produced by the Hall effect, dayside reconnection has basically a dipole structure. In the present study we selected 26 dayside reconnection events, based on simultaneous sign reversals of the ion outflow velocity and the magnetic field observed by Geotail from year 1994 to 2014. We find that the reconnection events have either quadrupole or dipole structure in the duskward magnetic field component (By). We further investigated the magnetic field structure near the neutral line by analyzing changes in the ion density and magnetic field when Geotail passed near the neutral line. In the quadrupole-structure cases, the ratio of the ion density in the magnetosheath to that at the magnetopause is 7.5 on average, and the ratio of Bz at the magnetopause to |Bz| in the magnetosheath is 1.5. On the other hand, in the dipole-structure cases, the average ion density ratio is 36.1, and the average magnetic field intensity ratio is 2.7. These values are greater than those for the quadrupole structure. These results indicate that dayside reconnection has the dipole structure in the Hall magnetic field when density asymmetry is large and the electron flux from the magnetosheath is much larger than that from the dayside magnetosphere. In the dipole structure, the Hall current flows along the separatrix toward and away from the diffusion region on the magnetosheath and magnetospheric sides, respectively. Title: Hinode and IRIS Observations of the Magnetohydrodynamic Waves Propagating from the Photosphere to the Chromosphere in a Sunspot Authors: Kanoh, Ryuichi; Shimizu, Toshifumi; Imada, Shinsuke Bibcode: 2016ApJ...831...24K Altcode: 2016arXiv160803910K Magnetohydrodynamic (MHD) waves have been considered as energy sources for heating the solar chromosphere and the corona. Although MHD waves have been observed in the solar atmosphere, there are a lack of quantitative estimates on the energy transfer and dissipation in the atmosphere. We performed simultaneous Hinode and Interface Region Imaging Spectrograph observations of a sunspot umbra to derive the upward energy fluxes at two different atmospheric layers (photosphere and lower transition region) and estimate the energy dissipation. The observations revealed some properties of the observed periodic oscillations in physical quantities, such as their phase relations, temporal behaviors, and power spectra, making a conclusion that standing slow-mode waves are dominant at the photosphere with their high-frequency leakage, which is observed as upward waves at the chromosphere and the lower transition region. Our estimates of upward energy fluxes are 2.0× {10}7 erg cm-2 s-1 at the photospheric level and 8.3× {10}4 erg cm-2 s-1 at the lower transition region level. The difference between the energy fluxes is larger than the energy required to maintain the chromosphere in the sunspot umbrae, suggesting that the observed waves can make a crucial contribution to the heating of the chromosphere in the sunspot umbrae. In contrast, the upward energy flux derived at the lower transition region level is smaller than the energy flux required for heating the corona, implying that we may need another heating mechanism. We should, however, note a possibility that the energy dissipated at the chromosphere might be overestimated because of the opacity effect. Title: Quantitative estimation of the energy flux during an explosive chromospheric evaporation in a white light flare kernel observed by Hinode, IRIS, SDO, and RHESSI Authors: Lee, Kyoung-Sun; Imada, Shinsuke; Kyoko, Watanabe; Bamba, Yumi; Brooks, David H. Bibcode: 2016usc..confE..77L Altcode: An X1.6 flare occurred at the AR 12192 on 2014 October 22 at14:02 UT was observed by Hinode, IRIS, SDO, and RHESSI. We analyze a bright kernel which produces a white light (WL) flare with continuum enhancement and a hard X-ray (HXR) peak. Taking advantage of the spectroscopic observations of IRIS and Hinode/EIS, we measure the temporal variation of the plasma properties in the bright kernel in the chromosphere and corona. We found that explosive evaporation was observed when the WL emission occurred, even though the intensity enhancement in hotter lines is quite weak. The temporal correlation of the WL emission, HXR peak, and evaporation flows indicate that the WL emission was produced by accelerated electrons. To understand the white light emission processes, we calculated the deposited energy flux from the non-thermal electrons observed by RHESSI and compared it to the dissipated energy estimated from the chromospheric line (Mg II triplet) observed by IRIS. The deposited energy flux from the non-thermal electrons is about 3.1 × 1010erg cm-2 s-1 when we consider a cut-off energy 20 keV. The estimated energy flux from the temperature changes in the chromosphere measured from the Mg II subordinate line is about 4.6-6.7×109erg cm-2 s-1, ∼ 15-22% of the deposited energy. By comparison of these estimated energy fluxes we conclude that the continuum enhancement was directly produced by the non-thermal electrons. Title: Project for Solar-Terrestrial Environment Prediction (PSTEP): Towards Predicting Next Solar Cycle Authors: Imada, S.; Iijima, H.; Hotta, H.; Shiota, D.; Kanou, O.; Fujiyama, M.; Kusano, K. Bibcode: 2016usc..confE..83I Altcode: It is believed that the longer-term variations of the solar activity can affect the Earth's climate. Therefore, predicting the next solar cycle is crucial for the forecast of the "solar-terrestrial environment". To build prediction schemes for the activity level of the next solar cycle is a key for the long-term space weather study. Although three-years prediction can be almost achieved, the prediction of next solar cycle is very limited, so far. We are developing a five-years prediction scheme by combining the Surface Flux Transport (SFT) model and the most accurate measurements of solar magnetic fields as a part of the PSTEP (Project for Solar-Terrestrial Environment Prediction),. We estimate the meridional flow, differential rotation, and turbulent diffusivity from recent modern observations (Hinode and Solar Dynamics Observatory). These parameters are used in the SFT models to predict the polar magnetic fields strength at the solar minimum. In this presentation, we will explain the outline of our strategy to predict the next solar cycle. We also report the present status and the future perspective of our project. Title: Boosting magnetic reconnection by viscosity and thermal conduction Authors: Minoshima, Takashi; Miyoshi, Takahiro; Imada, Shinsuke Bibcode: 2016PhPl...23g2122M Altcode: 2016arXiv160702839M Nonlinear evolution of magnetic reconnection is investigated by means of magnetohydrodynamic simulations including uniform resistivity, uniform viscosity, and anisotropic thermal conduction. When viscosity exceeds resistivity (the magnetic Prandtl number P r m > 1 ), the viscous dissipation dominates outflow dynamics and leads to the decrease in the plasma density inside a current sheet. The low-density current sheet supports the excitation of the vortex. The thickness of the vortex is broader than that of the current for P r m > 1 . The broader vortex flow more efficiently carries the upstream magnetic flux toward the reconnection region, and consequently, boosts the reconnection. The reconnection rate increases with viscosity provided that thermal conduction is fast enough to take away the thermal energy increased by the viscous dissipation (the fluid Prandtl number Pr < 1). The result suggests the need to control the Prandtl numbers for the reconnection against the conventional resistive model. Title: A Comparative Study of Confined and Eruptive Solar Flares using Microwave Observations Authors: Yashiro, S.; Akiyama, S.; Masuda, S.; Shimojo, M.; Asai, A.; Imada, S.; Gopalswamy, N. Bibcode: 2015AGUFMSH43B2447Y Altcode: It is well known that about 10% X-class solar flares are not associated with coronal mass ejections (CMEs). These flares are referred to as confined flares, which are not associated with mass or energetic particles leaving the Sun. However, electrons are accelerated to MeV energies as indicated by the presence of microwave emission with a turnover frequency of ~15 GHz (Gopalswamy et al. 2009, IAU Symposium 257, p. 283). In this paper, we extend the study of confined flares to lower soft X-ray flare sizes (M and above) that occurred in the time window of the Nobeyama Radioheliograph (NoRH). We also make use of the microwave spectral information from the Nobeyama Radio Polarimeters (NoRP). During 1996 - 2014, NoRH and NoRP observed 663 flares with size M1.0 or larger. Using the CME observations made by SOHO/LASCO and STEREO/SECCHI, we found 215 flares with definite CME association (eruptive flares) and 202 flares that definitely lacked CMEs (confined flares). The remaining 146 flares whose CME association is unclear are excluded from the analysis. We examined the peak brightness temperature and the spatial size obtained by NoRH. Although there is a large overlap between the two populations in these properties, we found that microwave sources with the largest spatial extent and highest brightness temperature are associated with eruptive flares. Spectral analysis using NoRP data showed a tendency that more confined flares had higher turnover frequency (≥17 GHz). We also compare the NoRH images with the photospheric magnetograms to understand the difference in the magnetic structure of the two types of flare sources. Title: Modeling of magnetically confined plasma in hot coronal loops Authors: Asgari-Targhi, M.; Imada, S.; Schmelz, J. T. Bibcode: 2015AGUFMSH13C2452A Altcode: In this talk, we present results of three-dimensional MHD modeling for the Alfvén wave turbulence within loops with high temperatures ⩾ 5 MK. One of our findings is that for the Alfvén waves to create enough turbulence to heat the loops in the core of the active region, the footpoint velocity must be 5-6 km/s. We also present the results of the non-thermal line broadenings in these loops and draw a comparison between the observations and modeling. Title: Energetic ion acceleration during magnetic reconnection in the Earth's magnetotail Authors: Imada, Shinsuke; Hirai, Mariko; Hoshino, Masahiro Bibcode: 2015EP&S...67..203I Altcode: In this paper, we present a comprehensive study of the energetic ion acceleration during magnetic reconnection in the Earth's magnetosphere using the Geotail data. A clear example of the energetic ion acceleration up to 1 MeV around an X-type neutral line is shown. We find that the energetic ions are localized at far downstream of reconnection outflow. The time variation of energetic ion and electron is almost the same. We observe ∼100 keV ions over the entire observation period. We study ten events in which the Geotail satellite observed in the vicinity of diffusion region in order to understand the reconnection characteristics that determine the energetic ion acceleration efficiency. We find that the reconnection electric field, total amount of reduced magnetic energy, reconnection rate, satellite location in the Earth's magnetosphere (both X GSM and Y GSM) show high correlation with energetic ion acceleration efficiency. Also, ion temperature, electron temperature, ion/electron temperature ratio, current sheet thickness, and electric field normal to the neutral sheet show low correlation. We do not find any correlation with absolute value of outflow velocity and current density parallel to magnetic field. The energetic ion acceleration efficiency is well correlated with large-scale parameters (e.g., total amount of reduced magnetic energy and satellite location), whereas the energetic electron acceleration efficiency is correlated with small-scale parameters (e.g., current sheet thickness and electric field normal to the neutral sheet). We conclude that the spatial size of magnetic reconnection is important for energetic ion acceleration in the Earth's magnetotail. Title: High-energy ions produced by two approaching flow fronts in the magnetotail Authors: Uchino, H.; Ieda, A.; Machida, S.; Imada, S. Bibcode: 2015AGUFMSM13D2549U Altcode: During a substorm event in 2009, THEMIS probes observed high-energy (≲ 1MeV) ions and characteristic time evolution of the differential flux. The high-energy ions seem to be produced in the magnetotail, but existing acceleration theories cannot explain the production of such high-energy ions due to the limitation of dawn-dusk (DD) flow scale. We propose that if two approaching flow fronts exist simultaneously in the magnetotail, the production of high-energy ions can be achieved. Namely, some ideal ions are repeatedly reflected by the two fronts and accelerated to high energies, exceeding the energy-limit given by the product of the duskward electric field and DD scale length of the flows. In addition, this acceleration model similar to "first-order Fermi acceleration" can produce the observed differential flux change. We have analytically calculated the energy-gain of each ion between two approaching flow fronts, and roughly estimated the efficiency of the acceleration and the spectrum change. In order to include the DD flow scale, we have further performed a spatially 1-D (2-D in velocity) test particle simulation where a couple of flow fronts approach each other. Using the simulation, we have confirmed the production of high-energy ions as well as the change of the energy spectrum of ions associated with the acceleration. The simulation result shows that high-energy ions can be produced with shorter DD scale length compared to that of the simple acceleration for trapped particles in the flow front. If we assume that the DD scale length of the flow is 10Re, the simulated ion maximum energy near 1MeV and differential flux change are similar to those of the observation. This scale length is less than half of the length needed for the product with the duskward electric field to produce 1MeV ions. This estimated 10Re flow scale in that event does not contradict previous studies. Title: Observation and numerical modeling of chromospheric evaporation during the impulsive phase of a solar flare Authors: Imada, Shinsuke; Murakami, Izumi; Watanabe, Tetsuya Bibcode: 2015PhPl...22j1206I Altcode: 2015arXiv150604674I We have studied the chromospheric evaporation flow during the impulsive phase of the flare by using the Hinode/EUV Imaging Spectrometer observation and 1D hydrodynamic numerical simulation coupled to the time-dependent ionization. The observation clearly shows that the strong redshift can be observed at the base of the flaring loop only during the impulsive phase. We performed two different numerical simulations to reproduce the strong downflows in FeXII and FeXV during the impulsive phase. By changing the thermal conduction coefficient, we carried out the numerical calculation of chromospheric evaporation in the thermal conduction dominant regime (conductivity coefficient κ0 = classical value) and the enthalpy flux dominant regime (κ0 = 0.1 × classical value). The chromospheric evaporation calculation in the enthalpy flux dominant regime could reproduce the strong redshift at the base of the flare during the impulsive phase. This result might indicate that the thermal conduction can be strongly suppressed in some cases of flare. We also find that time-dependent ionization effect is important to reproduce the strong downflows in Fe XII and Fe XV. Title: Photospheric Abundances of Polar Jets on the Sun Observed by Hinode Authors: Lee, Kyoung-Sun; Brooks, David H.; Imada, Shinsuke Bibcode: 2015ApJ...809..114L Altcode: 2015arXiv150704075L Many jets are detected at X-ray wavelengths in the Sun's polar regions, and the ejected plasma along the jets has been suggested to contribute mass to the fast solar wind. From in situ measurements in the magnetosphere, it has been found that the fast solar wind has photospheric abundances while the slow solar wind has coronal abundances. Therefore, we investigated the abundances of polar jets to determine whether they are the same as that of the fast solar wind. For this study, we selected 22 jets in the polar region observed by Hinode/EUV Imaging Spectroscopy (EIS) and X-ray Telescope (XRT) simultaneously on 2007 November 1-3. We calculated the First Ionization Potential (FIP) bias factor from the ratio of the intensity between high (S) and low (Si, Fe) FIP elements using the EIS spectra. The values of the FIP bias factors for the polar jets are around 0.7-1.9, and 75% of the values are in the range of 0.7-1.5, which indicates that they have photospheric abundances similar to the fast solar wind. The results are consistent with the reconnection jet model where photospheric plasma emerges and is rapidly ejected into the fast wind. Title: Modeling of Hot Plasma in the Solar Active Region Core Authors: Asgari-Targhi, M.; Schmelz, J. T.; Imada, S.; Pathak, S.; Christian, G. M. Bibcode: 2015ApJ...807..146A Altcode: Magnetically confined plasma with temperatures ≥slant 5 {MK} are a feature of hot coronal loops observed in the core of active regions. In this paper, using observations and MHD modeling of coronal loops, we investigate whether wave heating (Alternating Current) models can describe the high temperature loops observed in the active region of 2012 September 7. We construct three-dimensional MHD models for the Alfvén wave turbulence within loops with high temperature. We find that for the Alfvén waves to create enough turbulence to heat the corona, the rms velocity at the footpoints must be 5-6 {km} {{{s}}}-1. We conclude that the Alfvén wave turbulence model may be a candidate for explaining how the hot loops are heated, provided the loops have a high velocity at their photospheric footpoints. Title: Coronal behavior before the large flare onset Authors: Imada, Shinsuke; Bamba, Yumi; Kusano, Kanya Bibcode: 2014PASJ...66S..17I Altcode: 2014PASJ..tmp..103I; 2014arXiv1408.2585I Flares are a major explosive event in our solar system. They are often followed by a coronal mass ejection that has the potential to trigger geomagnetic storms. There are various studies aiming to predict when and where the flares are likely to occur. Most of these studies mainly discuss the photospheric and chromospheric activity before the flare onset. In this paper we study the coronal features before the famous large flare occurrence on 2006 December 13. Using the data from Hinode/Extreme ultraviolet Imaging Spectrometer (EIS), X-Ray Telescope (XRT), and Solar and Heliospheric Observatory (SOHO)/Extreme ultraviolet Imaging Telescope (EIT), we discuss the coronal features in the large scale (a few 100″) before the flare onset. Our findings are as follows. (1) The upflows in and around the active region start growing from ∼ 10 to 30 km s-1 a day before the flare. (2) The expanding coronal loops are clearly observed a few hours before the flare. (3) Soft X-ray and extreme ultraviolet intensity are gradually reduced. (4) The upflows are further enhanced after the flare. From these observed signatures, we conclude that the outer part of active region loops with low density was expanding a day before the flare onset, and the inner part with high density was expanding a few hours before the onset. Title: Comparison between Hinode/SOT and SDO/HMI, AIA data for the study of the solar flare trigger process Authors: Bamba, Yumi; Kusano, Kanya; Imada, Shinsuke; Iida, Yusuke Bibcode: 2014PASJ...66S..16B Altcode: 2014arXiv1407.1887B; 2014PASJ..tmp..124B Understanding the mechanism that produces solar flares is important not only from the scientific point of view but also for improving space weather predictability. There are numerous observational and computational studies that have attempted to reveal the onset mechanism of solar flares. However, the underlying mechanism of flare onset remains elusive. To elucidate the flare trigger mechanism, we analyzed several flare events which were observed by Hinode/Solar Optical Telescope (SOT) in our previous study. Because of the limitation of the SOT field of view, however, only four events in the Hinode data sets have been usable. Therefore, increasing the number of events is required for evaluating the flare trigger models. We investigated the applicability of data obtained by the Solar Dynamics Observatory (SDO) to increase the data sample for a statistical analysis of the flare trigger process. SDO regularly observes the full disk of the sun and all flares, although its spatial resolution is lower than that of Hinode. We investigated the M6.6 flare which occurred on 2011 February 13, and compared the analyzed data of SDO with the results of our previous study using Hinode/SOT data. Filter and vector magnetograms obtained by the Helioseismic and Magnetic Imager and filtergrams from the Atmospheric Imaging Assembly (AIA) 1600 Å were employed. From the comparison of small-scale magnetic configurations and chromospheric emission prior to the flare onset, we confirmed that the trigger region is detectable with the SDO data. We also measured the magnetic shear angles of the active region and the azimuth and strength of the flare trigger field. The results were consistent with our previous study. We concluded that statistical studies of the flare trigger process are feasible with SDO as well as Hinode data. We also investigated the temporal evolution of the magnetic field before the flare onset with SDO. Title: Investigation of solar wind dependence of the plasma sheet based on long-term Geotail/LEP data evaluation Authors: Saeki, R.; Seki, K.; Saito, Y.; Shinohara, I.; Miyashita, Y.; Imada, S.; Machida, S. Bibcode: 2014AGUFMSM53A..08S Altcode: It is observationally known that the plasma density and temperature in plasma sheet are significantly changed by solar wind conditions [e.g., Terasawa et al., 1997]. Thus it is considered that the plasma sheet plasma is originated from the solar wind, and several entry mechanisms have been suggested. When the interplanetary magnetic field (IMF) is southward, the solar wind plasma enters the plasma sheet mainly through magnetic reconnection at the dayside magnetopause. In contrast, for the northward IMF, the double-lobe reconnection [Song et al., 1999], abnormal diffusion [Johnson and Cheng., 1997], and plasma mixing through the Kelvin-Helmholtz instability caused by viscous interaction [Hasegawa et al., 2004] have been proposed. Relative contribution of each process is, however, far from understood. In the present study, we use magnetotail observations by the Geotail spacecraft at radial distances of 10-32 Re during 12-year period from 1995 to 2006 to investigate properties of the plasma sheet. We conducted a statistical analysis with calibrated LEP-EA [Mukai et al., 1994] ion and electron data. We selected central plasma sheet observations and derived electron and ion temperature and density using the same method and criteria as Terasawa et al. [1997]. In addition, OMNI solar-wind data are used. The results show that the plasma sheet density (both ion and electron temperatures) has a good correlation with the solar wind density (kinetic energy) over the whole solar cycle. We find clear dawn-dusk asymmetry in the temperature ratio Ti/Te, i.e., the average Ti/Te is higher on the duskside than the dawn. The density also shows the dawn-dusk asymmetry and higher on the duskside than on the dawnside. A previous study by Wang et al. [2012] showed that Ti/Te is high (typically 5-10) in the magnetosheath. The statistical results, therefore, suggest that the shocked solar wind plasma can easily enter the duskside plasma sheet rather than the dawnside. We will discuss the possible mechanisms of the entry of the cold plasma into the duskside plasma sheet. Title: Investigating Alfven Wave Turbulence in Chromosphere and Corona Using Extreme Ultraviolet Imaging Spectrometer (EIS) Authors: Asgari-Targhi, M.; Imada, S.; DeLuca, E. E. Bibcode: 2014AGUFMSH53D..07A Altcode: The solar corona is known to be very dynamic. Mass motions due to Alfven wave turbulence are one of the main causes of plasma flows within the coronal loops. Using observations from EIS we analyze the structure of active region loops observed on 2012 September 7. We study the spectral line profiles of Fe XII, Fe XIII, Fe XV and Fe XVI and compare the non-thermal line broadening from this region to line-of-sight velocity from our Alfven wave turbulence modeling of the loops. In our computations, the relationship between the width of the coronal emission lines and the orientation of the coronal loops with respect to the line-of-sight direction is taken in to account. We predict that in coronal loops, the transverse component of plasma flows with respect to the loop axis move at the speed of 15-40 km/s. In conclusion, Alfven waves are a strong candidate in explaining the flows within the coronal loops and play an important role in the heating of the chromosphere and corona. Title: Formation of a Flare-Productive Active Region: Observation and Numerical Simulation of NOAA AR 11158 Authors: Toriumi, S.; Iida, Y.; Kusano, K.; Bamba, Y.; Imada, S. Bibcode: 2014SoPh..289.3351T Altcode: 2014SoPh..tmp...40T; 2014arXiv1403.4029T We present a comparison of the Solar Dynamics Observatory (SDO) analysis of NOAA Active Region (AR) 11158 and numerical simulations of flux-tube emergence, aiming to investigate the formation process of this flare-productive AR. First, we use SDO/Helioseismic and Magnetic Imager (HMI) magnetograms to investigate the photospheric evolution and Atmospheric Imaging Assembly (AIA) data to analyze the relevant coronal structures. Key features of this quadrupolar region are a long sheared polarity inversion line (PIL) in the central δ-sunspots and a coronal arcade above the PIL. We find that these features are responsible for the production of intense flares, including an X2.2-class event. Based on the observations, we then propose two possible models for the creation of AR 11158 and conduct flux-emergence simulations of the two cases to reproduce this AR. Case 1 is the emergence of a single flux tube, which is split into two in the convection zone and emerges at two locations, while Case 2 is the emergence of two isolated but neighboring tubes. We find that, in Case 1, a sheared PIL and a coronal arcade are created in the middle of the region, which agrees with the AR 11158 observation. However, Case 2 never builds a clear PIL, which deviates from the observation. Therefore, we conclude that the flare-productive AR 11158 is, between the two cases, more likely to be created from a single split emerging flux than from two independent flux bundles. Title: The soft x-ray photon-counting telescope for solar observations Authors: Sakao, Taro; Narukage, Noriyuki; Suematsu, Yoshinori; Watanabe, Kyoko; Shimojo, Masumi; Imada, Shinsuke; Ishikawa, Shin-nosuke; DeLuca, Edward E. Bibcode: 2014SPIE.9144E..3DS Altcode: We present overview and development activities of a soft X-ray photon-counting spectroscopic imager for the solar corona that we conceive as a possible scientific payload for future space solar missions including Japanese Solar-C. The soft X-ray imager will employ a Wolter I grazing-incidence sector mirror with which images of the corona (1 MK to beyond 10 MK) will be taken with the highest-ever angular resolution (0.5"/pixel for a focal length of 4 m) as a solar Xray telescope. In addition to high-resolution imagery, we attempt to implement photon-counting capability for the imager by employing a backside-illuminated CMOS image sensor as the focal-plane device. Imaging-spectroscopy of the X-ray corona will be performed for the first time in the energy range from ~0.5 keV up to 10 keV. The imaging-spectroscopic observations with the soft X-ray imager will provide a noble probe for investigating mechanism(s) of magnetic reconnection and generation of supra-thermal (non-thermal) electrons associated with flares. Ongoing development activities in Japan towards the photon-counting imager is described with emphasis on that for sub-arcsecond-resolution grazing-incidence mirrors. Title: New developments in rotating and linear motion mechanisms used in contamination sensitive space telescopes Authors: Shimizu, Toshifumi; Watanabe, Kyoko; Nakayama, Satoshi; Tajima, Takao; Obara, Shingo; Imada, Shinsuke; Nishizuka, Naoto; Ishikawa, Shin-nosuke; Hara, Hirohisa Bibcode: 2014SPIE.9151E..38S Altcode: We have been developing a rotating mechanism and a linear motion mechanism for their usage in contamination sensitive space telescopes. They both are needed for ~1.4 meter optical telescope and its focal plane instrument onboard SOLAR-C, the next-generation spaceborne solar observatory following Hinode. Highly reliable long life performance, low outgassing properties, and low level of micro-vibration are required along with their scientific performance. With the proto-type mechanisms, the long life performance and outgassing properties of the mechanisms have been evaluated in vacuum chambers. The level of micro-vibration excited during the operations of the rotating mechanism was measured by operating it on the Kestler table. This paper provides the overall descriptions of our mechanism developments. Title: Observational Signatures of Alfven Wave Turbulence in Solar Coronal Loops Authors: Asgari-Targhi, Mahboubeh; Imada, Shinsuke; DeLuca, Edward E. Bibcode: 2014AAS...22432325A Altcode: The non-thermal width in coronal emission lines could be due to the Alfven wave turbulence. In order to find observational evidence of the Alfven waves that result in coronal heating, we examine and analyze the dynamics of an active region observed on 2012 September 7. We use spectral line profiles of Fe XII, Fe XIII, Fe XV and Fe XVI obtained by Extreme-ultraviolet Imaging Spectrometer (EIS) on Hinode spacecraft. Line profile observations from EIS were generated and compared with our computations of line of sight Alfven wave amplitude. We show non-thermal velocities, Doppler outflows, and intensities for loops in this active region and derive comparisons between our numerical results and observations from EIS. In our modeling we take into account the relationship between the width of the coronal emission lines and the orientation of the coronal loops with respect to the line-of-sight direction. We conclude that the Alfven wave turbulence model is a strong candidate for explaining how the observed loops are heated. Title: Comparison of Extreme Ultraviolet Imaging Spectrometer Observations of Solar Coronal Loops with Alfvén Wave Turbulence Models Authors: Asgari-Targhi, M.; van Ballegooijen, A. A.; Imada, S. Bibcode: 2014ApJ...786...28A Altcode: The observed non-thermal widths of coronal emission lines could be due to Alfvén wave turbulence. To test this idea, we examine and analyze the dynamics of an active region observed on 2012 September 7. We use spectral line profiles of Fe XII, Fe XIII, Fe XV, and Fe XVI obtained by the Extreme-ultraviolet Imaging Spectrometer on the it Hinode spacecraft. The observations show non-thermal velocities, Doppler outflows, and intensities for loops in this active region. The observed non-thermal velocities are compared with predictions from models for Alfvén wave turbulence in the observed coronal loops. This modeling takes into account the relationship between the width of the coronal emission lines and the orientation of the coronal loops with respect to the line-of-sight direction. We find that in order to produce the observed line widths we need to introduce a random parallel-flow component in addition to the perpendicular velocity due to Alfvén waves. The observed widths are consistent with photospheric footpoint velocities in the range 0.3-1.5 km s-1. We conclude that the Alfvén wave turbulence model is a strong candidate for explaining how the observed loops are heated. Title: Flux emergence and formation of a flare-productive active region Authors: Toriumi, Shin; Kusano, Kanya; Bamba, Yumi; Imada, Shinsuke; Iida, Yusuke Bibcode: 2014cosp...40E3375T Altcode: We present a comparison of the SDO observation of NOAA Active Region (AR) 11158 and numerical simulations, aiming to investigate the flux emergence and the resultant formation of a flare-productive AR. First, we use SDO/HMI magnetograms to investigate the emerging flux events in the photosphere and AIA data to analyze the corresponding coronal EUV evolutions. Key features of this quadrupolar region are a long sheared polarity inversion line (PIL) in the central delta-sunspots and a coronal arcade. We find that these features are responsible for the production of a series of intense flares including X- and M-class events. Based on the observations, we then propose two possible scenarios for the creation of AR 11158 and conduct flux emergence simulations of the two cases to reproduce this AR. Case 1 is the emergence of a single flux tube, which is split into two in the convection zone and emerges at two locations, while Case 2 is the emergence of two isolated, but neighboring, flux tubes. We find that, in Case 1, a sheared PIL and a coronal arcade are created in the middle of the region, which agrees well with the AR 11158 observation. However, Case 2 never build a clear PIL, which deviates from the observation. Therefore, we conclude that the flare-productive AR 11158 is, between the two models, more likely to be created from a single split emerging flux than two independent flux bundles. Title: Spectroscopic Study of a Dark Lane and a Cool Loop in a Solar Limb Active Region by Hinode/EIS Authors: Lee, Kyoung-Sun; Imada, S.; Moon, Y. -J.; Lee, Jin-Yi Bibcode: 2014ApJ...780..177L Altcode: We investigated a cool loop and a dark lane over a limb active region on 2007 March 14 using the Hinode/EUV Imaging Spectrometer. The cool loop is clearly seen in the spectral lines formed at the transition region temperature. The dark lane is characterized by an elongated faint structure in the coronal spectral lines and is rooted on a bright point. We examined their electron densities, Doppler velocities, and nonthermal velocities as a function of distance from the limb. We derived electron densities using the density sensitive line pairs of Mg VII, Si X, Fe XII, Fe XIII, and Fe XIV spectra. We also compared the observed density scale heights with the calculated scale heights from each peak formation temperatures of the spectral lines under the hydrostatic equilibrium. We noted that the observed density scale heights of the cool loop are consistent with the calculated heights, with the exception of one observed cooler temperature; we also found that the observed scale heights of the dark lane are much lower than their calculated scale heights. The nonthermal velocity in the cool loop slightly decreases along the loop, while nonthermal velocity in the dark lane sharply falls off with height. Such a decrease in the nonthermal velocity may be explained by wave damping near the solar surface or by turbulence due to magnetic reconnection near the bright point. Title: Velocity structure of solar flare plasmas Authors: Watanabe, Tetsuya; Watanabe, Kyoko; Hara, Hirohisa; Imada, Shinsuke Bibcode: 2014cosp...40E3606W Altcode: Thanks to its increased sensitivity and spectral resolution, EIS enabled emission line profile analysis for the first time in solar EUV spectroscopy, and it found detailed structures in velocity and temperature in solar flares. A widely accepted model for solar flares incorporates magnetic reconnection in the corona which results in local heating as well as acceleration of nonthermal particle beams. The standard model of solar flares is called the CSHKP model, arranging the initials of model proposers. We find loop-top hot source, fast outflows nearby, inflow structure flowing to the hot source that appeared in the impulsive phase of long-duration eruptive flares. From the geometrical relationships of these phenomena, we conclude that they provide evidence for magnetic reconnection that occurs near the loop-top region. The reconnection rate is estimated to 0.05 - 0.1, which supports the Petschek-type magnetic reconnection. The nonthermal particle beams will travel unimpeded until they reach the cold, dense chromosphere, where the energy of the beam is predominantly used to heat the chromosphere at the foot points of flaring loops. Explosive chromospheric evaporation happens when the beam energy is high enough that the chromosphere cannot radiate away energy fast enough and hence expands at high velocities into the corona. Spatially resolved observations of chromopheric evaporation during the initial phases of impulsive flares, a few bright points of Fexxiii and Fexxiv emission lines at the footpoints of flaring loops present dominated blue-shifted components of 300 - 400 kms (-1) , while Fexv/xvi lines are nearly stationary, and Feviii and Sivii lines present +50 kms (-1) red shifts. We will review these new views on dynamical structure in flares. Title: White-Light Emission and related Chromospheric Response in an X1.8-class Flare on 2012 October 23 Authors: Watanabe, Kyoko; Shimizu, Toshifumi; Imada, Shinsuke Bibcode: 2014cosp...40E3604W Altcode: In association with strong solar flares, we sometimes observe enhancements of visible continuum radiation, which is known as a ”white-light flare”. Because many observed events show a close correlation between the time profiles and locations of white-light emission, and the hard X-rays and/or radio emission, there is some consensus that the origin of white-light emission is non-thermal electrons. Generally, white-light emission is emitted from near the photosphere, however, non-thermal electrons are almost thermalized by the time they reach the lower chromosphere - and cannot reach the photosphere. So, still there is a problem concerning how the energy of non-thermal electrons propagates to the photosphere, and produces white-light emission. On October 23, 2012, white-light emission was observed by Hinode/SOT in association with the X1.8 class flare. Although the main phenomena of this solar flare occurred in a very compact region and the two Ca II H ribbons are separated by less than only 5 arcseconds, the white-light kernels are clearly observed along the Ca II H ribbons. Moreover, hard X-ray, and gamma-ray emission is present up to about 1 MeV, observed by the RHESSI satellite, and most of this emission is associated with the white-light kernels. The Hinode/EIS was also scanning over this flaring active region before the flare, and the flare occurred during the scan. Over the white-light kernel, strong red shifts were observed in FeXII etc. before the flare. In this paper, we will report the observed white-light emission, and chromospheric response obtained by the EUV observations. We also discuss the relationship between the downflows over the white-light kernel and the strength of the white-light emission, and try to show a possible prediction of how white-light emission can be produced by the transportation of non-thermal electrons. Title: A quantitative study of ionospheric disturbance characteristics during solar flare events using the SuperDARN Hokkaido radar and solar radiation data Authors: Watanabe, D.; Nishitani, N.; Imada, S. Bibcode: 2013AGUFMSA41B2106W Altcode: Ionospheric disturbances during solar flare events have been studied by various kinds of observation instrument in the last few decades. Kikuchi et al. (1985) reported on the positive Doppler shift in the HF Doppler system data during solar flare events, and indicated that there are two possible factors of Doppler shift, i.e., (1) apparent ray path decrease by changing refraction index due to increasing electron densities in the D-region ionosphere, and (2) ray path decrease due to descending reflection point associated with increasing electron density in the F-region ionosphere. In this study, we use the SuperDARN Hokkaido Radar to investigate the detailed characteristics of solar flare effects on ionospheric disturbances. We focus on the positive Doppler shift of ground / sea scatter echoes just before sudden fade-out of echoes. Davies et al. (1962) showed that if the factor (1) is dominant, the Doppler shift should have positive correlation with slant range and negative correlation with elevation angle and frequency. On the other hand, if the factor (2) is dominant, the Doppler shift should have negative correlation with slant range and positive correlation with elevation angle and frequency. While Kikuchi et al. (1985) studied solar flare events and mainly discussed frequency dependence of Doppler shift, we study mainly slant range and elevation angle dependence, for the first time to the best of our knowledge. We found that the factor (1), in other words, increase of electron densities at D-region ionosphere, is dominant during solar flare events. This result is consistent with that of Kikuchi et al. In order to study characteristics of ionospheric disturbance in more detail, we are studying relationship between timing / amplitude of ionospheric disturbance and that of the solar irradiation changes, by comparing the HF radar data with high wavelength resolution irradiation data for X-ray and EUV from RHESSI and SDO satellites. Generally, X-ray radiation becomes more important for the changes in the D-region during solar flare events. Therefore we investigate relationship between X-ray flux changes and electron density variation in the D-region ionosphere intensively. Further, we estimated electron density changes in the ionsosphere by analyzing elevation angle dependence of Doppler shift in radar echoes quantitatively. We are estimating electron density by considering chemical reaction and photoreaction caused by solar radiation. We will compare the two electron density changes deduced from different two ways and evaluate the amplitude of ionospheric disturbance observed by the HF radar. More detailed analysis result will be reported. Title: The Relationship between Extreme Ultraviolet Non-thermal Line Broadening and High-energy Particles during Solar Flares Authors: Kawate, T.; Imada, S. Bibcode: 2013ApJ...775..122K Altcode: 2013arXiv1308.3415K We have studied the relationship between the location of EUV non-thermal broadening and high-energy particles during large flares using the EUV Imaging Spectrometer on board Hinode, the Nobeyama Radio Polarimeter, the Nobeyama Radioheliograph, and the Atmospheric Imaging Assembly on board the Solar Dynamic Observatory. We have analyzed five large flare events that contain thermal-rich, intermediate, and thermal-poor flares classified by the definition discussed in the paper. We found that, in the case of thermal-rich flares, the non-thermal broadening of Fe XXIV occurred at the top of the flaring loop at the beginning of the flares. The source of 17 GHz microwaves is located at the footpoint of the flare loop. On the other hand, in the case of intermediate/thermal-poor flares, the non-thermal broadening of Fe XXIV occurred at the footpoint of the flare loop at the beginning of the flares. The source of 17 GHz microwaves is located at the top of the flaring loop. We discussed the difference between thermal-rich and intermediate/thermal-poor flares based on the spatial information of non-thermal broadening, which may provide clues that the presence of turbulence plays an important role in the pitch angle scattering of high-energy electrons. Title: Saturation of Stellar Winds from Young Suns Authors: Suzuki, Takeru K.; Imada, Shinsuke; Kataoka, Ryuho; Kato, Yoshiaki; Matsumoto, Takuma; Miyahara, Hiroko; Tsuneta, Saku Bibcode: 2013PASJ...65...98S Altcode: 2012arXiv1212.6713S We investigated mass losses via stellar winds from Sun-like main-sequence stars with a wide range of activity levels. We performed forward-type magnetohydrodynamical numerical experiments for Alfvén wave-driven stellar winds with a wide range of input Poynting flux from the photosphere. Increasing the magnetic field strength and the turbulent velocity at the stellar photosphere from the current solar level, the mass-loss rate rapidly at first increases, owing to suppression of the reflection of the Alfvén waves. The surface materials are lifted up by the magnetic pressure associated with the Alfvén waves, and the cool dense chromosphere is intermittently extended to 10%#8211;20% of the stellar radius. The dense atmospheres enhance the radiative losses, and eventually most of the input Poynting energy from the stellar surface escapes by radiation. As a result, there is no more sufficient energy remaining for the kinetic energy of the wind; the stellar wind saturates in very active stars, as observed in Wood et al. (2002, ApJ, 574, 412; 2005, ApJ, 628, L143). The saturation level is positively correlated with Br,0 f0, where Br,0 and f0 are the magnetic field strength and the filling factor of open flux tubes at the photosphere. If Br,0 f0 is relatively large gtrsim 5 G, the mass-loss rate could be as high as 1000 times. If such a strong mass loss lasts for ∼ 1 billion years, the stellar mass itself would be affected, which could be a solution to the faint young Sun paradox. We derived a Reimers-type scaling relation that estimates the mass-loss rate from an energetics consideration of our simulations. Finally, we derived the evolution of the mass-loss rates, dot;{M} ∝ t-1.23, of our simulations, combining with an observed time evolution of X-ray flux from Sun-like stars, which are shallower than dot;{M} ∝ t-2.33±0.55 in Wood et al. (2005). Title: Evidence for Hot Fast Flow above a Solar Flare Arcade Authors: Imada, S.; Aoki, K.; Hara, H.; Watanabe, T.; Harra, L. K.; Shimizu, T. Bibcode: 2013ApJ...776L..11I Altcode: 2013arXiv1309.3401I Solar flares are one of the main forces behind space weather events. However, the mechanism that drives such energetic phenomena is not fully understood. The standard eruptive flare model predicts that magnetic reconnection occurs high in the corona where hot fast flows are created. Some imaging or spectroscopic observations have indicated the presence of these hot fast flows, but there have been no spectroscopic scanning observations to date to measure the two-dimensional structure quantitatively. We analyzed a flare that occurred on the west solar limb on 2012 January 27 observed by the Hinode EUV Imaging Spectrometer (EIS) and found that the hot (~30MK) fast (>500 km s-1) component was located above the flare loop. This is consistent with magnetic reconnection taking place above the flare loop. Title: The Magnetic Systems Triggering the M6.6 Class Solar Flare in NOAA Active Region 11158 Authors: Toriumi, Shin; Iida, Yusuke; Bamba, Yumi; Kusano, Kanya; Imada, Shinsuke; Inoue, Satoshi Bibcode: 2013ApJ...773..128T Altcode: 2013arXiv1306.2451T We report a detailed event analysis of the M6.6 class flare in the active region (AR) NOAA 11158 on 2011 February 13. AR 11158, which consisted of two major emerging bipoles, showed prominent activity including one X- and several M-class flares. In order to investigate the magnetic structures related to the M6.6 event, particularly the formation process of a flare-triggering magnetic region, we analyzed multiple spacecraft observations and numerical results of a flare simulation. We observed that, in the center of this quadrupolar AR, a highly sheared polarity inversion line (PIL) was formed through proper motions of the major magnetic elements, which built a sheared coronal arcade lying over the PIL. The observations lend support to the interpretation that the target flare was triggered by a localized magnetic region that had an intrusive structure, namely, a positive polarity penetrating into a negative counterpart. The geometrical relationship between the sheared coronal arcade and the triggering region is consistent with the theoretical flare model based on the previous numerical study. We found that the formation of the trigger region was due to the continuous accumulation of small-scale magnetic patches. A few hours before the flare occurred, the series of emerged/advected patches reconnected with a pre-existing field. Finally, the abrupt flare eruption of the M6.6 event started around 17:30 UT. Our analysis suggests that in the process of triggering flare activity, all magnetic systems on multiple scales are included, not only the entire AR evolution but also the fine magnetic elements. Title: Hinode observations of the Venus corona during the 2012 transit of Venus Authors: Kanao, M.; Yamazaki, A.; Imada, S.; Shimizu, T.; Sakao, T.; Kasaba, Y.; Sakanoi, T.; Kagitani, M.; Nakamura, M. Bibcode: 2012AGUFM.P11D1851K Altcode: The Hinode satellite successfully observed the transit of Venus on 5th June 2012 with the highest spatial resolution. This presentation will focus on UV and soft X-ray data acquired with the EUV Imaging Spectrometer (EIS) and the X-ray Telescope (XRT) onboard Hinode. We expected the EUV and X-ray emissions from the charge exchange reaction by the solar wind impacting on the neutral particles in Venus upper atmosphere. The neutral particles escape through the photoreaction, the solar wind pick-up process, and so on, in connection with the solar wind and the solar radiation. However, there are few precedent observations of the escaping hydrogen and oxygen, ranging from a few eV to a few keV because of difficulty in the groundbased observations. The atmosphere loss can be estimated based on the two-dimensional image of the neutral particle density. Our estimation was made for 18.4nm (OVI), 19.3nm (OV) and 25.6nm (HII), which intensity and line profiles can be recorded with EIS, and 1.72-2.18nm (OVII), 1.60-1.90nm(OVIII), 2.85-3.37nm (CVI), 3.50-4.03 nm (CV), which are located in XRT's broadband range. Multi wavelength observation could clarify the collision velocities between the solar wind and Venus neutral particles. Before the transit of Venus, for science planning purpose, we estimated the EUV and X-ray emission intensities by using typical solar wind parameters (the proton density 10/cc and the solar wind velocity 400 km/sec) with a Venus atmosphere model. The photon production rate of the X-ray emission is estimated to be 1.1 x 10^25 photons/s, and that of the OVI emission line (18.4nm) is 6.9 x 10^23 photons/s. These values are much lower than the emissions from the solar corona, but unexpected signals may be observed dureing the transit. In this presentation, we will present the calculation results on intensity distribution of the Venus corona and some X-ray and EUV data acquired during the transit. Also we briefly compare the observed intensities in dark Venus feature with the calculation results and discuss the signification of the difference. Title: Spectroscopic Study of a Dark Lane and a Cool Loop in a Solar Limb Active Region by Hinode/EIS Authors: Lee, K.; Imada, S.; Moon, Y.; Lee, J. Bibcode: 2012AGUFMSH13A2241L Altcode: We investigate a cool loop and a dark lane over a limb active region on 2007 March 14 by the Hinode/EUV Imaging Spectrometer (EIS). The cool loop is clearly seen in the EIS spectral lines formed at the transition region temperature (log T = 5.8). The dark lane is characterized by an elongated faint structure in coronal spectral lines (log T = 5.8 - 6.1) and rooted on a bright point. We examine their electron densities, Doppler velocities, and non-thermal velocities as a function of distance from the limb using the spectral lines formed at different temperatures (log T = 5.4 - 6.4). The electron densities of the cool loop and the dark lane are derived from the density sensitive line pairs of Mg VII, Fe XII, and Fe XIV spectra. Under the hydrostatic equilibrium and isothermal assumption, we determine their temperatures from the density scale height. Comparing the scale height temperatures to the peak formation temperatures of the spectral lines, we note that the scale height temperature of the cool loop is consistent with a peak formation temperature of the Mg VII (log T = 5.8) and the scale height temperature of the dark lane is close to a peak formation temperature of the Fe XII and Fe XIII (log T = 6.1 - 6.2). It is interesting to note that the structures of the cool loop and the dark lane are most visible in these temperature lines. While the non-thermal velocity in the cool loop slightly decreases (less than 7 km {s-1}) along the loop, that in the dark lane sharply falls off with height. The variation of non-thermal velocity with height in the cool loop and the dark lane is contrast to that in off-limb polar coronal holes which are considered as source of the fast solar wind. Such a decrease in the non-thermal velocity may be explained by wave damping near the solar surface or turbulence due to magnetic reconnection near the bright point. Title: Multi-wavelength Spectroscopic Observation of Extreme-ultraviolet Jet in AR 10960 Authors: Matsui, Y.; Yokoyama, T.; Kitagawa, N.; Imada, S. Bibcode: 2012ApJ...759...15M Altcode: 2012arXiv1209.0867M We have studied the relationship between the velocity and temperature of a solar EUV jet. The highly accelerated jet occurred in the active region NOAA 10960 on 2007 June 5. Multi-wavelength spectral observations with EIS/Hinode allow us to investigate Doppler velocities at a wide temperature range. We analyzed the three-dimensional angle of the jet from stereoscopic analysis with STEREO. Using this angle and Doppler velocity, we derived the true velocity of the jet. As a result, we found that the cool jet observed with He II 256 Å log10 Te [K] = 4.9 is accelerated to around 220 km s-1, which is over the upper limit of the chromospheric evaporation. The velocities observed with the other lines are below the upper limit of the chromospheric evaporation, while most of the velocities of the hot lines are higher than those of cool lines. We interpret that the chromospheric evaporation and magnetic acceleration occur simultaneously. A morphological interpretation of this event based on the reconnection model is given by utilizing the multi-instrumental observations. Title: LEMUR: Large European module for solar Ultraviolet Research. European contribution to JAXA's Solar-C mission Authors: Teriaca, Luca; Andretta, Vincenzo; Auchère, Frédéric; Brown, Charles M.; Buchlin, Eric; Cauzzi, Gianna; Culhane, J. Len; Curdt, Werner; Davila, Joseph M.; Del Zanna, Giulio; Doschek, George A.; Fineschi, Silvano; Fludra, Andrzej; Gallagher, Peter T.; Green, Lucie; Harra, Louise K.; Imada, Shinsuke; Innes, Davina; Kliem, Bernhard; Korendyke, Clarence; Mariska, John T.; Martínez-Pillet, Valentin; Parenti, Susanna; Patsourakos, Spiros; Peter, Hardi; Poletto, Luca; Rutten, Robert J.; Schühle, Udo; Siemer, Martin; Shimizu, Toshifumi; Socas-Navarro, Hector; Solanki, Sami K.; Spadaro, Daniele; Trujillo-Bueno, Javier; Tsuneta, Saku; Dominguez, Santiago Vargas; Vial, Jean-Claude; Walsh, Robert; Warren, Harry P.; Wiegelmann, Thomas; Winter, Berend; Young, Peter Bibcode: 2012ExA....34..273T Altcode: 2011ExA...tmp..135T; 2011arXiv1109.4301T The solar outer atmosphere is an extremely dynamic environment characterized by the continuous interplay between the plasma and the magnetic field that generates and permeates it. Such interactions play a fundamental role in hugely diverse astrophysical systems, but occur at scales that cannot be studied outside the solar system. Understanding this complex system requires concerted, simultaneous solar observations from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at high spatial resolution (between 0.1'' and 0.3''), at high temporal resolution (on the order of 10 s, i.e., the time scale of chromospheric dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the chromosphere to the flaring corona), and the capability of measuring magnetic fields through spectropolarimetry at visible and near-infrared wavelengths. Simultaneous spectroscopic measurements sampling the entire temperature range are particularly important. These requirements are fulfilled by the Japanese Solar-C mission (Plan B), composed of a spacecraft in a geosynchronous orbit with a payload providing a significant improvement of imaging and spectropolarimetric capabilities in the UV, visible, and near-infrared with respect to what is available today and foreseen in the near future. The Large European Module for solar Ultraviolet Research (LEMUR), described in this paper, is a large VUV telescope feeding a scientific payload of high-resolution imaging spectrographs and cameras. LEMUR consists of two major components: a VUV solar telescope with a 30 cm diameter mirror and a focal length of 3.6 m, and a focal-plane package composed of VUV spectrometers covering six carefully chosen wavelength ranges between 170 Å and 1270 Å. The LEMUR slit covers 280'' on the Sun with 0.14'' per pixel sampling. In addition, LEMUR is capable of measuring mass flows velocities (line shifts) down to 2 km s - 1 or better. LEMUR has been proposed to ESA as the European contribution to the Solar C mission. Title: Chromospheric Lyman-alpha spectro-polarimeter (CLASP) Authors: Kano, Ryouhei; Bando, Takamasa; Narukage, Noriyuki; Ishikawa, Ryoko; Tsuneta, Saku; Katsukawa, Yukio; Kubo, Masahito; Ishikawa, Shin-nosuke; Hara, Hirohisa; Shimizu, Toshifumi; Suematsu, Yoshinori; Ichimoto, Kiyoshi; Sakao, Taro; Goto, Motoshi; Kato, Yoshiaki; Imada, Shinsuke; Kobayashi, Ken; Holloway, Todd; Winebarger, Amy; Cirtain, Jonathan; De Pontieu, Bart; Casini, Roberto; Trujillo Bueno, Javier; Štepán, Jiří; Manso Sainz, Rafael; Belluzzi, Luca; Asensio Ramos, Andres; Auchère, Frédéric; Carlsson, Mats Bibcode: 2012SPIE.8443E..4FK Altcode: One of the biggest challenges in heliophysics is to decipher the magnetic structure of the solar chromosphere. The importance of measuring the chromospheric magnetic field is due to both the key role the chromosphere plays in energizing and structuring the outer solar atmosphere and the inability of extrapolation of photospheric fields to adequately describe this key boundary region. Over the last few years, significant progress has been made in the spectral line formation of UV lines as well as the MHD modeling of the solar atmosphere. It is found that the Hanle effect in the Lyman-alpha line (121.567 nm) is a most promising diagnostic tool for weaker magnetic fields in the chromosphere and transition region. Based on this groundbreaking research, we propose the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) to NASA as a sounding rocket experiment, for making the first measurement of the linear polarization produced by scattering processes and the Hanle effect in the Lyman-alpha line (121.567 nm), and making the first exploration of the magnetic field in the upper chromosphere and transition region of the Sun. The CLASP instrument consists of a Cassegrain telescope, a rotating 1/2-wave plate, a dual-beam spectrograph assembly with a grating working as a beam splitter, and an identical pair of reflective polarization analyzers each equipped with a CCD camera. We propose to launch CLASP in December 2014. Title: The x-ray/EUV telescope for the Solar-C mission: science and development activities Authors: Sakao, Taro; Narukage, Noriyuki; Imada, Shinsuke; Suematsu, Yoshinori; Shimojo, Masumi; Tsuneta, Saku; DeLuca, Edward E.; Watanabe, Kyoko; Ishikawa, Shin-nosuke Bibcode: 2012SPIE.8443E..0AS Altcode: We report science and development activities of the X-ray/EUV telescope for the Japanese Solar-C mission whose projected launch around 2019. The telescope consists of a package of (a) a normal-incidence (NI) EUV telescope and (b) a grazing-incidence (GI) soft X-ray telescope. The NI telescope chiefly provides images of low corona (whose temperature 1 MK or even lower) with ultra-high angular resolution (0.2-0.3"/pixel) in 3 wavelength bands (304, 171, and 94 angstroms). On the other hand, the GI telescope provides images of the corona with a wide temperature coverage (1 MK to beyond 10 MK) with the highest-ever angular resolution (~0.5"/pixel) as a soft X-ray coronal imager. The set of NI and GI telescopes should provide crucial information for establishing magnetic and gas-dynamic connection between the corona and the lower atmosphere of the Sun which is essential for understanding heating of, and plasma activities in, the corona. Moreover, we attempt to implement photon-counting capability for the GI telescope with which imaging-spectroscopy of the X-ray corona will be performed for the first time, in the energy range from ~0.5 keV up to 10 keV. The imaging-spectroscopic observations will provide totally-new information on mechanism(s) for the generation of hot coronal plasmas (heated beyond a few MK), those for magnetic reconnection, and even generation of supra-thermal electrons associated with flares. An overview of instrument outline and science for the X-ray photoncounting telescope are presented, together with ongoing development activities in Japan towards soft X-ray photoncounting observations, focusing on high-speed X-ray CMOS detector and sub-arcsecond-resolution GI mirror. Title: Flare Onset Observed with Hinode in the 2006 December 13 Flare Authors: Asai, A.; Hara, H.; Watanabe, T.; Imada, S. Bibcode: 2012ASPC..454..303A Altcode: We present a detailed examination of the preflare phenomena of the X3.4 flare that occurred on 2006 December 13. This flare was associated with a faint arc-shaped ejection, which is thought to be an MHD fast-mode shock wave, seen in the soft X-ray images taken with the Hinode X-Ray Telescope (XRT), just at the start of the impulsive phase of the flare. Even before the ejection, we found many preflare features, such as an S-shaped brightening (sigmoid) with XRT, chromospheric brightening at the footpoints of the sigmoid loops with the Solar Optical Telescope (SOT), a faint X-ray eruption with XRT, and so on. The EUV Imaging Spectrometer (EIS) also observed the flare, and therefore, enabled us to examine the spectroscopic features. We discuss these phenomena and the energy release prosses. Title: Self-organization of Reconnecting Plasmas to Marginal Collisionality in the Solar Corona Authors: Imada, S.; Zweibel, E. G. Bibcode: 2012ApJ...755...93I Altcode: 2012arXiv1206.2706I We explore the suggestions by Uzdensky and Cassak et al. that coronal loops heated by magnetic reconnection should self-organize to a state of marginal collisionality. We discuss their model of coronal loop dynamics with a one-dimensional hydrodynamic calculation. We assume that many current sheets are present, with a distribution of thicknesses, but that only current sheets thinner than the ion skin depth can rapidly reconnect. This assumption naturally causes a density-dependent heating rate which is actively regulated by the plasma. We report nine numerical simulation results of coronal loop hydrodynamics in which the absolute values of the heating rates are different but their density dependences are the same. We find two regimes of behavior, depending on the amplitude of the heating rate. In the case that the amplitude of heating is below a threshold value, the loop is in stable equilibrium. Typically, the upper and less dense part of a coronal loop is collisionlessly heated and conductively cooled. When the amplitude of heating is above the threshold, the conductive flux to the lower atmosphere required to balance collisionless heating drives an evaporative flow which quenches fast reconnection, ultimately cooling and draining the loop until the cycle begins again. The key elements of this cycle are gravity and the density dependence of the heating function. Some additional factors are present, including pressure-driven flows from the loop top, which carry a large enthalpy flux and play an important role in reducing the density. We find that on average the density of the system is close to the marginally collisionless value. Title: Multi-wavelength Observations of an EUV Jet in AR 10960 Authors: Matsui, Y.; Yokoyama, T.; Imada, S. Bibcode: 2012ASPC..456...47M Altcode: We analyzed the fine structure of a solar EUV jet based on the magnetic reconnection model. Multi-wavelength spectral observations with EIS allow us to know Doppler velocities at the wide temperature range. What we found is as follows: (1) The jet consists of multi-temperature plasma in a few 104 rm{K} to a few MK range. (2) The observed speed of the jet does not have dependence on the plasma temperature that is expected by the evaporation scenario. We interpret that the chromospheric evaporation jet have been accelerated by the magnetic Lorentz force over the speed expected by the evaporation scenario. Title: Clear Detection of Chromospheric Evaporation Upflows with High Spatial/Temporal Resolution by Hinode XRT Authors: Nitta, S.; Imada, S.; Yamamoto, T. T. Bibcode: 2012SoPh..276..183N Altcode: We find clear evidence for typical chromospheric evaporation associated with small transient brightenings, using the data from the X-ray Telescope (XRT) onboard Hinode. We found 13 events, each having a pair of evaporation upflows arising almost symmetrically from both foot points of a magnetic loop. These facts strongly support the standard flare model based on the magnetic reconnection. The apparent upflow velocities of three of the events are ≈ 500 km s−1, while those of the other events are ≈ 100 km s−1. This is the first clear direct detection of evaporating upflow motion in soft X-ray images from Hinode/XRT; such images were obtained with high cadence (≈ 60 s) and high spatial resolution (1 arcsec). Title: Dynamical Behaviors of the Solar Chromosphere Observed with Hinode Dynamics in Sunspot Light Bridges and Magnetic Reconnection Processes Authors: Shimizu, Toshifumi; Imada, Shinsuke Bibcode: 2012ASSP...33...23S Altcode: 2012msdp.book...23S The Hinode's Solar Optical Telescope has revealed that the solar chromosphere is full of dynamical nature and much more dynamic than our thought. Observations of chromospheric dynamics in sunspot light bridges provides a new insight on the magnetic field topology for causing magnetic reconnection in the solar atmosphere and the process to supply and maintain the twisted flux in light bridges. Title: One-dimensional Modeling for Temperature-dependent Upflow in the Dimming Region Observed by Hinode/EUV Imaging Spectrometer Authors: Imada, S.; Hara, H.; Watanabe, T.; Murakami, I.; Harra, L. K.; Shimizu, T.; Zweibel, E. G. Bibcode: 2011ApJ...743...57I Altcode: 2011arXiv1108.5031I We previously found a temperature-dependent upflow in the dimming region following a coronal mass ejection observed by the Hinode EUV Imaging Spectrometer (EIS). In this paper, we reanalyzed the observations along with previous work on this event and provided boundary conditions for modeling. We found that the intensity in the dimming region dramatically drops within 30 minutes from the flare onset, and the dimming region reaches the equilibrium stage after ~1 hr. The temperature-dependent upflows were observed during the equilibrium stage by EIS. The cross-sectional area of the flux tube in the dimming region does not appear to expand significantly. From the observational constraints, we reconstructed the temperature-dependent upflow by using a new method that considers the mass and momentum conservation law and demonstrated the height variation of plasma conditions in the dimming region. We found that a super-radial expansion of the cross-sectional area is required to satisfy the mass conservation and momentum equations. There is a steep temperature and velocity gradient of around 7 Mm from the solar surface. This result may suggest that the strong heating occurred above 7 Mm from the solar surface in the dimming region. We also showed that the ionization equilibrium assumption in the dimming region is violated, especially in the higher temperature range. Title: Magnetic Reconnection in Non-equilibrium Ionization Plasma Authors: Imada, S.; Murakami, I.; Watanabe, T.; Hara, H.; Shimizu, T. Bibcode: 2011ApJ...742...70I Altcode: 2011arXiv1108.5026I We have studied the effect of time-dependent ionization and the recombination processes on magnetic reconnection in the solar corona. Petschek-type steady reconnection, in which the magnetic energy is mainly converted at the slow-mode shocks, was assumed. We carried out the time-dependent ionization calculation in the magnetic reconnection structure. We only calculated the transient ionization of iron; the other species were assumed to be in ionization equilibrium. The intensity of line emissions at specific wavelengths was also calculated for comparison with Hinode or other observations in future. We found the following: (1) iron is mostly in non-equilibrium ionization in the reconnection region; (2) the intensity of line emission estimated by the time-dependent ionization calculation is significantly different from that determined from the ionization equilibrium assumption; (3) the effect of time-dependent ionization is sensitive to the electron density in the case where the electron density is less than 1010 cm-3 (4) the effect of thermal conduction lessens the time-dependent ionization effect; and (5) the effect of radiative cooling is negligibly small even if we take into account time-dependent ionization. Title: Photon-counting soft x-ray telescope for the Solar-C mission Authors: Sakao, Taro; Narukage, Noriyuki; Shimojo, Masumi; Tsuneta, Saku; Suematsu, Yoshinori; Miyazaki, Satoshi; Imada, Shinsuke; Nishizuka, Naoto; Watanabe, Kyoko; Dotani, Tadayasu; DeLuca, Edward E.; Ishikawa, Shin-nosuke Bibcode: 2011SPIE.8148E..0CS Altcode: 2011SPIE.8148E..11S We report instrument outline as well as science of the photon-counting soft X-ray telescope that we have been studying as a possible scientific payload for the Japanese Solar-C mission whose projected launch around 2019. Soft X-rays (~1- 10 keV) from the solar corona include rich information on (1) possible mechanism(s) for heating the bright core of active regions seen in soft X-rays (namely, the hottest portion in the non-flaring corona), (2) dynamics and magnetohydrodynamic structures associated with magnetic reconnection processes ongoing in flares, and even (3) generation of supra-thermal distributions of coronal plasmas associated with flares. Nevertheless, imaging-spectroscopic investigation of the soft X-ray corona has so far remained unexplored due to difficulty in the instrumentation for achieving this aim. With the advent of recent remarkable progress in CMOS-APS detector technology, the photon-counting X-ray telescope will be capable of, in addition to conventional photon-integration type exposures, performing imaging-spectroscopic investigation on active regions and flares, thus providing, for example, detailed temperature information (beyond the sofar- utilized filter-ratio temperature) at each spatial point of the observing target. The photon-counting X-ray telescope will emply a Wolter type I optics with a piece of a segmented mirror whose focal length 4 meters, combined with a focal-plane CMOS-APS detector (0.4-0.5"/pixel) whose frame read-out rate required to be as high as 1000 fps. Title: Favorable conditions for energetic electron acceleration during magnetic reconnection in the Earth's magnetotail Authors: Imada, S.; Hirai, M.; Hoshino, M.; Mukai, T. Bibcode: 2011JGRA..116.8217I Altcode: We have studied favorable conditions for energetic electron acceleration during magnetic reconnection in the Earth's magnetosphere using the Geotail data. We have found the strong energetic electron acceleration in some reconnection events. On the other hand, the other reconnection events show weak electron acceleration. To discuss what reconnection characteristics determine energetic electron acceleration efficiency, we have studied the reconnection characteristics for 10 events in which the Geotail satellite observed the vicinity of the diffusion region. We have classified the relationship between the reconnection characteristics and the electron acceleration efficiency into three types: (1) good correlation (absolute value of correlation coefficient ∣r∣ > 0.6); (2) ambiguous correlation (0.6 > ∣r∣ > 0.3); and (3) no correlation (0.3 > ∣r∣). We found that ion heating, electron heating, current sheet thickness, reconnection electric field, and converging normal electric field could be categorized into good correlation. Ion/electron temperature ratio, total amount of reconnected magnetic energy, and reconnection rate were classified in ambiguous correlation. We could not find any correlation between energetic electron acceleration efficiency and absolute value of outflow velocity, current density parallel to magnetic field (Hall current system), and satellite location in the Earth's magnetosphere. From our analysis we claimed that the electrons are efficiently accelerated in a thin current sheet during fast reconnection events. Title: Two Types of Extreme-ultraviolet Brightenings In AR 10926 Observed by Hinode/EIS Authors: Lee, K. -S.; Moon, Y. -J.; Kim, Sujin; Choe, G. S.; Cho, Kyung-Suk; Imada, S. Bibcode: 2011ApJ...736...15L Altcode: We have investigated seven extreme-ultraviolet (EUV) brightenings in the active region AR 10926 on 2006 December 2 observed by the EUV Imaging Spectrometer on board the Hinode spacecraft. We have determined their Doppler velocities and non-thermal velocities from 15 EUV spectral lines (log T = 4.7 - 6.4) by fitting each line profile to a Gaussian function. The Doppler velocity maps for different temperatures are presented to show the height dependence of the Doppler shifts. It is found that the active region brightenings show two distinct Doppler shift patterns. The type 1 brightening shows a systematic increase of Doppler velocity from -68 km s-1 (strong blueshift) at log T = 4.7 to -2 km s-1 (weak blueshift) at log T = 6.4, while the type 2 brightenings have Doppler velocities in the range from -20 km s-1 to 20 km s-1. The type 1 brightening point is considered to sit in an upward reconnection outflow whose speed decreases with height. In both types of brightenings, the non-thermal velocity is found to be significantly enhanced at log T = 5.8 compared to the background region. We have also determined electron densities from line ratios and derived temperatures from emission measure loci using the CHIANTI atomic database. The electron densities of all brightenings are comparable to typical values in active regions (log Ne = 9.9-10.4). The emission measure loci plots indicate that these brightenings should be multi-thermal whereas the background is isothermal. The differential emission measure as a function of temperature shows multiple peaks in the EUV brightening regions, while it has only a single peak (log T = 6.0) in the background region. Using Michelson Doppler Imager magnetograms, we have found that the type 1 brightening is associated with a canceling magnetic feature with a flux canceling rate of 2.4 × 1018 Mx hr-1. We also found the canceling magnetic feature and chromospheric brightenings in the type 1 brightening from the Hinode SOT and Transition Region and Coronal Explorer data. This observation corroborates our argument that brightening is caused by magnetic reconnection in a low atmosphere. Title: Morphology, dynamics and plasma parameters of plumes and inter-plume regions in solar coronal holes Authors: Wilhelm, K.; Abbo, L.; Auchère, F.; Barbey, N.; Feng, L.; Gabriel, A. H.; Giordano, S.; Imada, S.; Llebaria, A.; Matthaeus, W. H.; Poletto, G.; Raouafi, N. -E.; Suess, S. T.; Teriaca, L.; Wang, Y. -M. Bibcode: 2011A&ARv..19...35W Altcode: 2011arXiv1103.4481W Coronal plumes, which extend from solar coronal holes (CH) into the high corona and—possibly—into the solar wind (SW), can now continuously be studied with modern telescopes and spectrometers on spacecraft, in addition to investigations from the ground, in particular, during total eclipses. Despite the large amount of data available on these prominent features and related phenomena, many questions remained unanswered as to their generation and relative contributions to the high-speed streams emanating from CHs. An understanding of the processes of plume formation and evolution requires a better knowledge of the physical conditions at the base of CHs, in plumes and in the surrounding inter-plume regions. More specifically, information is needed on the magnetic field configuration, the electron densities and temperatures, effective ion temperatures, non-thermal motions, plume cross sections relative to the size of a CH, the plasma bulk speeds, as well as any plume signatures in the SW. In spring 2007, the authors proposed a study on `Structure and dynamics of coronal plumes and inter-plume regions in solar coronal holes' to the International Space Science Institute (ISSI) in Bern to clarify some of these aspects by considering relevant observations and the extensive literature. This review summarizes the results and conclusions of the study. Stereoscopic observations allowed us to include three-dimensional reconstructions of plumes. Multi-instrument investigations carried out during several campaigns led to progress in some areas, such as plasma densities, temperatures, plume structure and the relation to other solar phenomena, but not all questions could be answered concerning the details of plume generation process(es) and interaction with the SW. Title: Determining the Solar Source of a Magnetic Cloud Using a Velocity Difference Technique Authors: Harra, L. K.; Mandrini, C. H.; Dasso, S.; Gulisano, A. M.; Steed, K.; Imada, S. Bibcode: 2011SoPh..268..213H Altcode: 2010SoPh..tmp..210H; 2010SoPh..tmp..234H For large eruptions on the Sun, it is often a problem that the core dimming region cannot be observed due to the bright emission from the flare itself. However, spectroscopic data can provide the missing information through the measurement of Doppler velocities. In this paper we analyse the well-studied flare and coronal mass ejection that erupted on the Sun on 13 December 2006 and reached the Earth on 14 December 2006. In this example, although the imaging data were saturated at the flare site itself, by using velocity measurements we could extract information on the core dimming region, as well as on remote dimmings. The purpose of this paper is to determine more accurately the magnetic flux of the solar source region, potentially involved in the ejection, through a new technique. The results of its application are compared to the flux in the magnetic cloud observed at 1 AU, as a way to check the reliability of this technique. We analysed data from the Hinode EUV Imaging Spectrometer to estimate the Doppler velocity in the active region and its surroundings before and after the event. This allowed us to determine a Doppler velocity `difference' image. We used the velocity difference image overlayed on a Michelson Doppler Imager magnetogram to identify the regions in which the blue shifts were more prominent after the event; the magnetic flux in these regions was used as a proxy for the ejected flux and compared to the magnetic cloud flux. This new method provides a more accurate flux determination in the solar source region. Title: Magnetic Reconnection in the Solar Atmopshere Observed by Hinode Authors: Imada, Shinsuke; Isobe, Hiroaki; Shimizu, Toshifumi Bibcode: 2011sswh.book...63I Altcode: No abstract at ADS Title: Ionization non-equilibrium plasma during magnetic reconnection in solar corona Authors: Imada, S.; Murakami, I.; Watanabe, T.; Hara, H.; Shimizu, T. Bibcode: 2010AGUFMSH31A1788I Altcode: Hinode can provide us both of the stored magnetic field energy in corona before magnetic reconnection and the most part of energy post reconnection stage. On the other hand, there is not enough observational knowledge of the physical parameters in the reconnection region. The inflow into the reconnection region, the temperature of the plasma in the reconnection region, and the temperatures and densities of the plasma jets predicted by reconnection, have not been quantitatively measured in sufficient. EIS on Hinode may provide some answers if solar cycle 24 ever produces a solar maximum. But it is important to answer why the most observation cannot detect the predicted flow or temperature in the reconnection region. One of the reasons why we cannot observe inside the magnetic reconnection region is due to its darkness. Generally we can see the bright cusp-like structure during solar flare, although the reconnection region is faint/blind. One may think that the temperature in the reconnection region is enough higher than that of cusp-like flare loops. Thus the wavelength of emission from reconnection region is different from flare loops. However, this is not entirely true. Magnetic reconnection causes rapid heating. Thus ionization cannot reach to the equilibrium stage. We have calculated the ionization process in the down stream of Petschek type magnetic reconnection. From our result, we can clearly see that plasma cannot reach the ionization equilibrium in the down stream of slow-mode shock. The typical emissions from magnetic reconnection region are FeIXX or FeXX, although the plasma temperature is equal to 40MK. The typical temperature and density of post flare loops are 10 MK and 10^11 /cc, and the dominant emissions from post flare loops are from FeIXX to FeXXIII. Thus the wavelength of emission from reconnection region is not so much different from post flare loops. We will discuss how the emissions from reconnection region looks like by using several ionization calculations of magnetic reconnection. Title: On the Origin of the Solar Moreton Wave of 2006 December 6 Authors: Balasubramaniam, K. S.; Cliver, E. W.; Pevtsov, A.; Temmer, M.; Henry, T. W.; Hudson, H. S.; Imada, S.; Ling, A. G.; Moore, R. L.; Muhr, N.; Neidig, D. F.; Petrie, G. J. D.; Veronig, A. M.; Vršnak, B.; White, S. M. Bibcode: 2010ApJ...723..587B Altcode: We analyzed ground- and space-based observations of the eruptive flare (3B/X6.5) and associated Moreton wave (~850 km s-1 ~270° azimuthal span) of 2006 December 6 to determine the wave driver—either flare pressure pulse (blast) or coronal mass ejection (CME). Kinematic analysis favors a CME driver of the wave, despite key gaps in coronal data. The CME scenario has a less constrained/smoother velocity versus time profile than is the case for the flare hypothesis and requires an acceleration rate more in accord with observations. The CME picture is based, in part, on the assumption that a strong and impulsive magnetic field change observed by a GONG magnetograph during the rapid rise phase of the flare corresponds to the main acceleration phase of the CME. The Moreton wave evolution tracks the inferred eruption of an extended coronal arcade, overlying a region of weak magnetic field to the west of the principal flare in NOAA active region 10930. Observations of Hα foot point brightenings, disturbance contours in off-band Hα images, and He I 10830 Å flare ribbons trace the eruption from 18:42 to 18:44 UT as it progressed southwest along the arcade. Hinode EIS observations show strong blueshifts at foot points of this arcade during the post-eruption phase, indicating mass outflow. At 18:45 UT, the Moreton wave exhibited two separate arcs (one off each flank of the tip of the arcade) that merged and coalesced by 18:47 UT to form a single smooth wave front, having its maximum amplitude in the southwest direction. We suggest that the erupting arcade (i.e., CME) expanded laterally to drive a coronal shock responsible for the Moreton wave. We attribute a darkening in Hα from a region underlying the arcade to absorption by faint unresolved post-eruption loops. Title: Experimental Simulation of Magnetic Reconnection in the Sunspot Light Bridge Authors: Hayashi, Yoshinori; Tanabe, Hiroshi; Inomoto, Michiaki; Ono, Yasushi; Shimizu, Toshifumi; Imada, Shinsuke; Nishizuka, Naoto Bibcode: 2010APS..DPPCP9122H Altcode: Intermittent and recurrent chromospheric plasma ejections were discovered in the sunspot light bridge (LB) by the Solar Optical Telescope of the Hinode satellite (Shimizu et al. 2009, ApJ, 696, L66). Strong current was observed under the jet, suggesting existence of twisted flux tube in the vertical background field. The magnetic reconnection between the flux tube and the vertical field is considered to cause the plasma ejection. It is left unsolved why the intermittent reconnection continuing more than one day. Note that the magnetic configuration of LB is similar to the spheromak plasma maintained by vertical field in the laboratory. We formed spheromak in the TS-4 device and drove magnetic reconnection with center solenoid coil. We measured 2D magnetic profile of the reconnecting field lines between the spheromak and the solenoid coil by the magnetic probe array and local temperature, density and plasma flow at the reconnection point by the Langmuir probes and ion Doppler spectroscopy. We will discuss about the LB reconnection by comparing the laboratory experiment with the satellite observation. Title: Mode Identification of MHD Waves in an Active Region Observed with Hinode/EIS Authors: Kitagawa, N.; Yokoyama, T.; Imada, S.; Hara, H. Bibcode: 2010ApJ...721..744K Altcode: 2010arXiv1008.1823K In order to better understand the possibility of coronal heating by MHD waves, we analyze Fe XII 195.12Å data observed with the EUV Imaging Spectrometer on board Hinode. We performed a Fourier analysis of EUV intensity and Doppler velocity time series data in the active region corona. Notable intensity and Doppler velocity oscillations were found for two moss regions out of the five studied, while only small oscillations were found for five apexes of loops. The amplitudes of the oscillations were 0.4%-5.7% for intensity and 0.2-1.2 km s-1 for Doppler velocity. In addition, oscillations of only the Doppler velocity were seen relatively less often in the data. We compared the amplitudes of intensity and those of Doppler velocity in order to identify MHD wave modes and calculated the phase delays between Fourier components of intensity and those of Doppler velocity. The results are interpreted in terms of MHD waves as follows: (1) few kink modes or torsional Alfvén mode waves were seen in both moss regions and the apexes of loops, (2) upwardly propagating and standing slow mode waves were found in moss regions, and (3) consistent with previous studies, estimated values of energy flux of the waves were several orders of magnitude lower than that required for heating active regions. Title: Accelerating Waves in Polar Coronal Holes as Seen by EIS and SUMER Authors: Gupta, G. R.; Banerjee, D.; Teriaca, L.; Imada, S.; Solanki, S. Bibcode: 2010ApJ...718...11G Altcode: 2010arXiv1005.3453G We present EIS/Hinode and SUMER/SOHO observations of propagating disturbances detected in coronal lines in inter-plume and plume regions of a polar coronal hole. The observation was carried out on 2007 November 13 as part of the JOP196/HOP045 program. The SUMER spectroscopic observation gives information about fluctuations in radiance and on both resolved (Doppler shift) and unresolved (Doppler width) line-of-sight velocities, whereas EIS 40'' wide slot images detect fluctuations only in radiance but maximize the probability of overlapping field of view between the two instruments. From distance-time radiance maps, we detect the presence of propagating waves in a polar inter-plume region with a period of 15-20 minutes and a propagation speed increasing from 130 ± 14 km s-1 just above the limb to 330 ± 140 km s-1 around 160'' above the limb. These waves can be traced to originate from a bright region of the on-disk part of the coronal hole where the propagation speed is in the range of 25 ± 1.3 to 38 ± 4.5 km s-1, with the same periodicity. These on-disk bright regions can be visualized as the base of the coronal funnels. The adjacent plume region also shows the presence of propagating disturbances with the same range of periodicity but with propagation speeds in the range of 135 ± 18 to 165 ± 43 km s-1 only. A comparison between the distance-time radiance map of the two regions indicates that the waves within the plumes are not observable (may be getting dissipated) far off-limb, whereas this is not the case in the inter-plume region. A correlation analysis was also performed to find out the time delay between the oscillations at several heights in the off-limb region, finding results consistent with those from the analysis of the distance-time maps. To our knowledge, this result provides first spectroscopic evidence of the acceleration of propagating disturbances in the polar region close to the Sun (within 1.2 R/R sun), which provides clues to the understanding of the origin of these waves. We suggest that the waves are likely either Alfvénic or fast magnetoacoustic in the inter-plume region and slow magnetoacoustic in the plume region. This may lead to the conclusion that inter-plumes are a preferred channel for the acceleration of the fast solar wind. Title: Accelerating disturbances in polar plume and inter-plume Authors: Gupta, Girjesh R.; Banerjee, Dipankar; Teriaca, Luca; Imada, Shinsuke; Solanki, Sami Bibcode: 2010cosp...38.2937G Altcode: 2010cosp.meet.2937G We present EIS/Hinode & SUMER/SoHO joint observations allowing the first spectroscopic detection of accelerating disturbances as recorded with coronal lines in inter-plume and plume regions of a polar coronal hole. From time-distance radiance maps, we detect the presence of propagating disturbances in a polar inter-plume region with a period of 15 to 20 min and a propagation speed increasing from 130±14 km/s just above the limb, to 330±140 km/s around 160" above the limb. These disturbances can also be traced to originate from a bright region of the on-disk part of the coronal hole where the propagation speed was found to be in the range of 25±1.3 to 38±4.5 km/s, with the same periodicity. These on-disk bright regions can be vi-sualized as the base of the coronal funnels. The adjacent plume region also shows the presence of propagating disturbance with the same range of period but with propagation speeds in the range of 135±18 to 165±43 km/s only. A comparison between the time-distance radiance map of both regions, indicate that the disturbances within the plumes are not observable (may be getting dissipated) far off-limb whereas this is not the case in the inter-plume region. Conclu-sions drawn from these observations in terms of accelerating waves or high speed jets/upflows will be discussed. Title: Comparison of reconnection in magnetosphere and solar corona Authors: Imada, Shinsuke; Hirai, Mariko; Isobe, Hiroaki; Oka, Mitsuo; Watanabe, Kyoko; Minoshima, Takashi Bibcode: 2010cosp...38.1940I Altcode: 2010cosp.meet.1940I One of the most famous rapid energy conversion mechanisms in space is a magnetic reconnec-tion. The general concept of a magnetic reconnection is that the rapid energy conversion from magnetic field energy to thermal energy, kinetic energy or non-thermal particle energy. The understanding of rapid energy conversion rates from magnetic field energy to other energy is the fundamental and essential problem in the space physics. One of the important goals for studying magnetic reconnection is to answer what plasma condition/parameter controls the energy conversion rates. Earth's magnetotail has been paid much attention to discuss a mag-netic reconnection, because we can discuss magnetic reconnection characteristics in detail with direct in-situ observation. Recently, solar atmosphere has been focused as a space laboratory for magnetic reconnection because of its variety in plasma condition. So far considerable effort has been devoted toward understanding the energy conversion rates of magnetic reconnection, and various typical features associated with magnetic reconnection have been observed in the Earth's magnetotail and the solar corona. In this talk, we first introduce the variety of plasma condition/parameter in solar corona and Earth's magnetotail. Later, we discuss what plasma condition/parameter controls the energy conversion from magnetic field to especially non-thermal particle. To compare non-thermal electron and ion acceleration in magnetic reconnection, we used Hard X-ray (electron) /Neu-tron monitor (ion) for solar corona and Geotail in-situ measurement (electron and ion) for magnetoatil. We found both of electron and ion accelerations are roughly controlled by re-connection electric field (reconnection rate). However, some detail points are different in ion and electron acceleration. Further, we will discuss what is the major difference between solar corona and Earth's magnetotail for particle acceleration. Title: Ion Temperature and Non-Thermal Velocity in a Solar Active Region: Using Emission Lines of Different Atomic Species Authors: Imada, S.; Hara, H.; Watanabe, T. Bibcode: 2009ApJ...705L.208I Altcode: We have studied the characteristics of the ion thermal temperature and non-thermal velocity in an active region observed by the EUV Imaging Spectrometer onboard Hinode. We used two emission lines of different atomic species (Fe XVI 262.98 Å and S XIII 256.69 Å) to distinguish the ion thermal velocity from the observed full width at half-maximum. We assumed that the sources of the two emission lines are the same thermal temperature. We also assumed that they have the same non-thermal velocity. With these assumptions, we could obtain the ion thermal temperature, after noting that M sulfur ~ 0.6M iron. We have carried out the ion thermal temperature analysis in the active region where the photon counts are sufficient (>4500). What we found is as follows: (1) the common ion thermal temperatures obtained by Fe XVI and S XIII are ~2.5 MK, (2) the typical non-thermal velocities are ~13 km s-1, (3) the highest non-thermal velocities (>20 km s-1) are preferentially observed between the bright points in Fe XVI, while (4) the hottest material (>3 MK) is observed relatively inside the bright points compared with the highest non-thermal velocity region. Title: Coronal Mass Ejection Induced Outflows Observed with Hinode/EIS Authors: Jin, M.; Ding, M. D.; Chen, P. F.; Fang, C.; Imada, S. Bibcode: 2009ApJ...702...27J Altcode: We investigate the outflows associated with two halo coronal mass ejections (CMEs) that occurred on 2006 December 13 and 14 in NOAA 10930, using the Hinode/EIS observations. Each CME was accompanied by an EIT wave and coronal dimmings. Dopplergrams in the dimming regions are obtained from the spectra of seven EIS lines. The results show that strong outflows are visible in the dimming regions during the CME eruption at different heights from the lower transition region to the corona. It is found that the velocity is positively correlated with the photospheric magnetic field, as well as the magnitude of the dimming. We estimate the mass loss based on height-dependent EUV dimmings and find it to be smaller than the CME mass derived from white-light observations. The mass difference is attributed partly to the uncertain atmospheric model, and partly to the transition region outflows, which refill the coronal dimmings. Title: Evidence from the Extreme-Ultraviolet Imaging Spectrometer for Axial Filament Rotation before a Large Flare Authors: Williams, David R.; Harra, Louise K.; Brooks, David H.; Imada, Shinsuke; Hansteen, Viggo H. Bibcode: 2009PASJ...61..493W Altcode: In this article, we present observations made with the Extreme-ultraviolet Imaging Spectrometer on-board the Hinode solar satellite, of an active region filament in the HeII emission line at 256.32Å. The host active region AR 10930 produces an X-class flare during these observations. We measure Doppler shifts with apparent velocities of up to 20km s-1, which are antisymmetric about the filament length and occur several minutes before the flare's impulsive phase. This is indicative of a rotation of the filament, which is in turn consistent with expansion of a twisted flux rope due to the MHD helical kink instability. This is the first time that such an observation has been possible in this transition-region line, and we note that the signature observed occurs before the first indications of pre-flare activity in the GOES solar soft X-ray flux, suggesting that the filament begins to destabilise in tandem with a reorganization of the local magnetic field. We suggest that this expansion is triggered by the decrease of magnetic tension around, and/or total pressure above, the filament. Title: Propagating waves in polar coronal holes as seen by SUMER & EIS Authors: Banerjee, D.; Teriaca, L.; Gupta, G. R.; Imada, S.; Stenborg, G.; Solanki, S. K. Bibcode: 2009A&A...499L..29B Altcode: 2009arXiv0905.1013B Context: To study the dynamics of coronal holes and the role of waves in the acceleration of the solar wind, spectral observations were performed over polar coronal hole regions with the SUMER spectrometer on SoHO and the EIS spectrometer on Hinode.
Aims: Using these observations, we aim to detect the presence of propagating waves in the corona and to study their properties.
Methods: The observations analysed here consist of SUMER spectra of the Ne viii 770 Å line (T = 0.6 MK) and EIS slot images in the Fe xii 195 Å line (T = 1.3 MK). Using the wavelet technique, we study line radiance oscillations at different heights from the limb in the polar coronal hole regions.
Results: We detect the presence of long period oscillations with periods of 10 to 30 min in polar coronal holes. The oscillations have an amplitude of a few percent in radiance and are not detectable in line-of-sight velocity. From the time distance maps we find evidence for propagating velocities from 75 km s-1 (Ne viii) to 125 km s-1 (Fe xii). These velocities are subsonic and roughly in the same ratio as the respective sound speeds.
Conclusions: We interpret the observed propagating oscillations in terms of slow magneto-acoustic waves. These waves can be important for the acceleration of the fast solar wind. Title: Multiwavelength Observation of Electron Acceleration in the 2006 December 13 Flare Authors: Minoshima, T.; Imada, S.; Morimoto, T.; Kawate, T.; Koshiishi, H.; Kubo, M.; Inoue, S.; Isobe, H.; Masuda, S.; Krucker, S.; Yokoyama, T. Bibcode: 2009ApJ...697..843M Altcode: 2009arXiv0903.1144M We present a multiwavelength observation of a solar flare occurring on 2006 December 13 with Hinode, RHESSI, and the Nobeyama Radio Observatory to study the electron acceleration site and mechanism. The Solar Optical Telescope (SOT) on board Hinode observed elongated flare ribbons, and RHESSI observed double-footpoint hard X-ray (HXR) sources appearing in part of the ribbons. A photospheric vector magnetogram obtained from SOT reveals that the HXR sources are located at the region where horizontal magnetic fields change direction. The region is interpreted as the footpoint of magnetic separatrix. Microwave images taken with the Nobeyama Radioheliograph show a loop structure connecting the HXR sources. The brighter parts of the microwave intensity are located between the top and footpoints of the loop. We consider these observations as evidence of electron acceleration near the magnetic separatrix and injection parallel to the field line. Title: Observational Study of Particle Acceleration in the 2006 December 13 Flare Authors: Minoshima, T.; Morimoto, T.; Kawate, T.; Imada, S.; Koshiishi, H.; Masuda, S.; Kubo, M.; Inoue, S.; Isobe, H.; Krucker, S.; Yokoyama, T. Bibcode: 2008AGUFMSH41B1619M Altcode: We study the particle acceleration in a flare on 2006 December 13, by using the Hinode, RHESSI, Nobeyama Radio Polarimeters (NoRP) and Nobeyama Radioheliograph (NoRH) observations. For technical reasons, both RHESSI and NoRH have a problem in imaging in this flare. Since we have succeeded in solving the problem, it is now possible to discuss the particle acceleration mechanism from an image analysis. This flare shows very long-lasting (1 hour) non-thermal emissions, consisting of many spikes. We focus on the second major spike at 02:29 UT, because the RHESSI image is available only in this period. The RHESSI 35-100 keV HXR image shows double sources located at the footpoints of the western soft X-ray (SXR) loop seen by the Hinode/XRT. The non-linear force-free (NLFF) modeling based on a magnetogram data by Inoue et al. shows the NLFF to potential magnetic transition of the loop, which would induce the electric field and then accelerate particles. Overlaying the HXR image on the photospheric three-dimensional magnetic field map taken by the Hinode Spectro-Polarimeter, we find that the HXR sources are located at the region where the horizontal magnetic fields invert. The NoRH 34 GHz microwave images show the loop structure connecting the HXR sources. The microwave peaks do not located at the top of the loop but between the loop top and the footpoints. The NoRP microwave spectrum shows the soft-hard-soft pattern in the period, same as the HXR spectrum (Ning 2008). From these observational results we suggest that the electrons were accelerated parallel to the magnetic field line near the magnetic separatrix. Title: The dawn-dusk asymmetry of energetic electron in the Earth's magnetotail: Observation and transport models Authors: Imada, S.; Hoshino, M.; Mukai, T. Bibcode: 2008JGRA..11311201I Altcode: We have studied the dawn-dusk asymmetry of the energetic/thermal particle in the plasma sheet using the Geotail data. We found the species- and energy-dependent dawn-dusk asymmetries in the plasma sheet. The dawn-dusk asymmetries have some typical structures, and we used a finite width two-dimensional model of the magnetotail to explain their characteristics. The characteristics and assumptions of our model can be summarized as follows: (1) the magnetotail convection is steady (both of magnetic field and electric field is steady), (2) the directions of electric fields are duskward, (3) the directions of magnetic fields are northward, (4) the magnetic field gradient is constant for earthward (constant for other directions), (5) the width of the magnetotail is constant in the entire plasma sheet (40 RE), (6) the plasma source region is steady at XGSM ∼ -100 RE, (7) the magnetic moment μ is conserved during transport, and (8) the particle spatial diffusion takes place only for dawn-dusk direction. In this model, we found that the energetic electrons cannot be provided sufficiently at the dusk flank with the simple adiabatic process (no spatial diffusion). Furthermore we applied the Bohm-type diffusion to the model and found that the observed asymmetries are well reproduced in the case that the diffusion coefficient is equal to 0.006/0.03vrg for electron/ion. Title: Strongly Blueshifted Phenomena Observed with Hinode EIS in the 2006 December 13 Solar Flare Authors: Asai, Ayumi; Hara, Hirohisa; Watanabe, Tetsuya; Imada, Shinsuke; Sakao, Taro; Narukage, Noriyuki; Culhane, J. L.; Doschek, G. A. Bibcode: 2008ApJ...685..622A Altcode: 2008arXiv0805.4468A We present a detailed examination of strongly blueshifted emission lines observed with the EUV Imaging Spectrometer on board the Hinode satellite. We found two kinds of blueshifted phenomenon associated with the X3.4 flare that occurred on 2006 December 13. One was related to a plasmoid ejection seen in soft X-rays. It was very bright in all the lines used for the observations. The other was associated with the faint arc-shaped ejection seen in soft X-rays. The soft X-ray ejection is thought to be a magnetohydrodynamic (MHD) fast-mode shock wave. This is therefore the first spectroscopic observation of an MHD fast-mode shock wave associated with a flare. Title: Doppler Shifts in the Boundary of the Dimming Region Authors: Imada, S.; Hara, H.; Watanabe, T.; Asai, A.; Kamio, S.; Matsuzaki, K.; Harra, L. K.; Mariska, J. T. Bibcode: 2008ASPC..397..102I Altcode: We present Hinode/EIS raster scan observations of the GOES X3.2 flare that occurred on 2006 December 13. There was a small transient coronal hole which was located 200 arcsec east of the flare arcade. The transient coronal hole was strongly affected by the X-class flare, and the strong upflows were observed in Fe XV line 284.2 Å (log{T/{K}} = 6.3) at the boundary of dimming region. In this paper, we discuss how to obtain the velocity map by correcting the instrumental effects. Title: Non-Gaussian Line Profiles in a Large Solar Flare Observed on 2006 December 13 Authors: Imada, S.; Hara, H.; Watanabe, T.; Asai, A.; Minoshima, T.; Harra, L. K.; Mariska, J. T. Bibcode: 2008ApJ...679L.155I Altcode: We have studied the characteristics of the non-Gaussian line profile of the Fe XIV 274.20 Å line in and around a flare arcade. We found that broad non-Gaussian line profiles associated with redshifts are observed in the flare arcade. There were two typical types of broad line profiles. One was a distorted line profile caused by multiple flows, and the other was a symmetric line profile without any additional component. We successfully distinguished those two types using higher order statistical moments or M—the additional component contribution—defined in this Letter. The distorted/symmetric broad line profiles were preferentially observed in new/old flare loops, respectively. Title: Outflows at the Edges of Active Regions: Contribution to Solar Wind Formation? Authors: Harra, L. K.; Sakao, T.; Mandrini, C. H.; Hara, H.; Imada, S.; Young, P. R.; van Driel-Gesztelyi, L.; Baker, D. Bibcode: 2008ApJ...676L.147H Altcode: The formation of the slow solar wind has been debated for many years. In this Letter we show evidence of persistent outflow at the edges of an active region as measured by the EUV Imaging Spectrometer on board Hinode. The Doppler velocity ranged between 20 and 50 km s-1 and was consistent with a steady flow seen in the X-Ray Telescope. The latter showed steady, pulsing outflowing material and some transverse motions of the loops. We analyze the magnetic field around the active region and produce a coronal magnetic field model. We determine from the latter that the outflow speeds adjusted for line-of-sight effects can reach over 100 km s-1. We can interpret this outflow as expansion of loops that lie over the active region, which may either reconnect with neighboring large-scale loops or are likely to open to the interplanetary space. This material constitutes at least part of the slow solar wind. Title: Erratum: "Outflows at the Edges of Active Regions: Contribution to Solar Wind Formation?" (ApJ, 676, L147 [2008]) Authors: Harra, L. K.; Sakao, T.; Mandrini, C. H.; Hara, H.; Imada, S.; Young, P. R.; van Driel-Gesztelyi, L.; Baker, D. Bibcode: 2008ApJ...677L.159H Altcode: No abstract at ADS Title: Observation of energetic electrons within magnetic islands Authors: Chen, L. -J.; Bhattacharjee, A.; Puhl-Quinn, P. A.; Yang, H.; Bessho, N.; Imada, S.; Mühlbachler, S.; Daly, P. W.; Lefebvre, B.; Khotyaintsev, Y.; Vaivads, A.; Fazakerley, A.; Georgescu, E. Bibcode: 2008NatPh...4...19C Altcode: Magnetic reconnection is the underlying process that releases impulsively an enormous amount of magnetic energy in solar flares , flares on strongly magnetized neutron stars and substorms in the Earth's magnetosphere. Studies of energy release during solar flares, in particular, indicate that up to 50% of the released energy is carried by accelerated 20-100keV suprathermal electrons. How so many electrons can gain so much energy during reconnection has been a long-standing question. A recent theoretical study suggests that volume-filling contracting magnetic islands formed during reconnection can produce a large number of energetic electrons. Here we report the first evidence of the link between energetic electrons and magnetic islands during reconnection in the Earth's magnetosphere. The results indicate that energetic electron fluxes peak at sites of compressed density within islands, which imposes a new constraint on theories of electron acceleration. Title: Discovery of a Temperature-Dependent Upflow in the Plage Region During a Gradual Phase of the X-Class Flare Authors: Imada, Shinsuke; Hara, Hirohisa; Watanabe, Tetsuya; Kamio, Suguru; Asai, Ayumi; Matsuzaki, Keiichi; Harra, Louise K.; Mariska, John T. Bibcode: 2007PASJ...59S.793I Altcode: We present Hinode/EIS raster scan observations of the plage region taken during the gradual phase of the GOES X3.2 flare that occurred on 2006 December 13. The plage region is located 200" east of the flare arcade. The plage region has a small transient coronal hole. The transient coronal hole is strongly affected by an X-class flare, and upflows are observed at its boundary. Multi-wavelength spectral observations allow us to determine velocities from the Doppler shifts at different temperatures. Strong upflows along with stationary plasma have been observed in the FeXV line 284.2Å (log T / K = 6.3) in the plage region. The strong upflows reach almost 150kms-1, which was estimated by a two-component Gaussian fitting. On the other hand, at a lower corona/transition region temperature (HeII, 256.3Å, log T / K = 4.9), very weak upflows, almost stationary, have been observed. We find that these upflow velocities clearly depend on the temperature with the hottest line, FeXV, showing the fastest upflow velocity and the second-highest line, FeXIV, showing the second-highest upflow velocity (130kms-1). All velocities are below the sound speed. The trend of the upflow dependence on temperature dramatically changes at 1MK. These results suggest that heating may have an important role for strong upflow. Title: Coronal Dimming Observed with Hinode: Outflows Related to a Coronal Mass Ejection Authors: Harra, Louise K.; Hara, Hirohisa; Imada, Shinsuke; Young, Peter R.; Williams, David R.; Sterling, Alphonse C.; Korendyke, Clarence; Attrill, Gemma D. R. Bibcode: 2007PASJ...59S.801H Altcode: Coronal dimming has been a signature used to determine the source of plasma that forms part of a coronal mass ejection (CME) for many years. Generally dimming is detected through imaging instruments such as SOHO EIT by taking difference images. Hinode tracked active region 10930 from which there were a series of flares. We combined dimming observations from EIT with Hinode data to show the impact of flares and coronal mass ejections on the region surrounding the flaring active region, and we discuss evidence that the eruption resulted in a prolonged steady outflow of material from the corona. The dimming region shows clear structure with extended loops whose footpoints are the source of the strongest outflow (≈ 40 kms-1). This confirms that the loops that are disrupted during the event do lose plasma and hence are likely to form part of the CME. This is the first time the velocity of the coronal plasma has been measured in an extended dimming region away from the flare core. In addition there was a weaker steady outflow from extended, faint loops outside the active region before the eruption, which is also long lasting. These were disturbed and the velocity increased following the flare. Such outflows could be the source of the slow solar wind. Title: Cluster observation of magnetic islands and energetic electrons Authors: Chen, L.; Bhattacharjee, A.; Puhl-Quinn, P. A.; Yang, H.; Bessho, N.; Imada, S.; Muehlbachler, S.; Daly, P.; Lefebvre, B.; Fazakerley, A.; Georgescu, E.; Mouikis, C. Bibcode: 2007AGUSMSM53C..06C Altcode: Magnetic reconnection is widely accepted to be a mechanism for electron acceleration, but exactly how electrons are accelerated during reconnection remains a long-standing question. A series of magnetic islands is observed in the magnetotail current sheet during active reconnection by multiple spacecraft. Electrons are hot within islands. The islands move away from the main reconnection sites with a velocity ~ 500 km/s based on multi-spacecraft timing analysis. The electric current distribution within an island varies significantly over a fraction of an ion inertial length in the out-of-plane direction, necessitating a 3D description. Associated with each island, is a burst of energetic electrons with energies ~35 to 120 keV. High time-resolution data reveal that energetic electron fluxes peak at sites of compressed density within magnetic islands. Within the islands, the density of O+ is higher than that of H+. The O+ ions are unmagnetized, and their density exhibits similar compression as the electron density, indicating that the density compression is not due to magnetic trapping by contracting islands, but most likely, due to the continuous injection of the ion and electron jets from the two reconnection sites bounding an island. The observation establishes a link between energetic electrons and magnetic islands, and provides supporting evidence for multiple reconnection sites. Title: Particle Acceleration in the X3 Event on Dec. 13, 2007 Authors: Shibasaki, Kiyoto; Koshiishi, H.; Shimojo, M.; Minoshima, T.; Imada, S.; Sakao, T.; Hinode Team Bibcode: 2007AAS...210.9435S Altcode: 2007BAAS...39..223S Even during the solar minimum period, the active region NOAA 10930 had a complex magnetic configuration especially around the main sunspot and produced a couple of X-class events. The one on Dec. 13, 2007 was well observed by Nobeyama Radioheliograph (NoRH) and Polarimeters (NoRP). Microwave emission associated with this event has several interesting characteristics:

1. Long lasting non-thermal phase

2. Very large decimetric flux (several thousand times of the quiet sun flux) and quite different time development of decimetric emission compared to shorter wavelengths

3. Very high turn-over frequency (around 35 GHz)

This event was also well observed by HINODE satellite and partially by RHESSI satellite. Optical telescope (SOT) and Soft X-ray telescope (XRT) onboard HINODE showed that the flare started around the polarity reversal line which divides the main sunspot and the closely associated small sunspot with opposite polarity. This line is the interface of the penumbrae of both sunspots. The flare ribbons started in the penumbrae and entered into umbrae of both sunspots.

Microwave images of the event at 17 and 34 GHz are synthesized and compared with optical and soft X-ray images taken by SOT and XRT respectively. Based on these overlays, frequency spectral information (NoRP) and RHESSI images in the later phase of the event, we try to locate particle acceleration site and discuss possible mechanisms of acceleration.

Hinode is an international project supported by JAXA, NASA, PPARC and ESA. We are grateful to the Hinode team for all their efforts in the design, development and operation of the mission. NoRH and NoRP are operated by Nobeyama Solar Radio Observatory, NAOJ. RHESSI is a NASA project. Title: Energetic electron acceleration in the downstream reconnection outflow region Authors: Imada, S.; Nakamura, R.; Daly, P. W.; Hoshino, M.; Baumjohann, W.; Mühlbachler, S.; Balogh, A.; RèMe, H. Bibcode: 2007JGRA..112.3202I Altcode: 2007JGRA..11203202I Energetic electrons in an earthward reconnection outflow region have been observed by Cluster/Research with Adaptive Particle Imaging Detectors. We found a good correlation between the energetic electron enhancement and a normal magnetic field (Bz) enhancement within a 0.25-s time resolution. The large normal magnetic field is thought to be associated with magnetic reconnection because the negative/positive Bz reversal observed during the fast proton tailward/earthward flow reversal is a good indicator of magnetic reconnection. Using the four-spacecraft Cluster, we can clearly see that this large positive Bz structure propagates in the earthward direction. Furthermore, we find that the energy spectrum of the energetic electrons becomes harder toward the downstream region. A negative Bz enhancement is also observed. The intensity of energetic electron enhancement associated with the negative Bz enhancement is weaker than that associated with the positive one. To discuss the temporal and spatial profile of energetic electron acceleration in the magnetic reconnection region, we determined the spacecraft position in the temporally evolving magnetic structures of reconnection. Our observation clearly indicates second-step acceleration, in addition to X line acceleration, of energetic electrons in the downstream reconnection outflow region. Title: Electron acceleration by impulsive reconnection near separatrices: Cluster observations Authors: Mühlbachler, S.; Chen, L.; Imada, S.; Puhl-Quinn, P.; Lefebvre, B.; Bhattacharjee, A.; Daly, P.; Georgescu, E. Bibcode: 2006AGUFMSM43C..05M Altcode: Near a magnetotail reconnection site, energetic electron bursts (50-100 keV) were observed by the Cluster spacecraft. These bursts correlate closely with spiky electric fields and pulse-like structures in the magnetic field. The spiky electric fields have DC components greater than 20 mV/m and AC components reaching 300 mV/m peak to peak. The pulse-like magnetic structures have Δ B/B ~ 1 and time durations comparable to one proton gyroperiod. Most of the energetic electron bursts were observed near the separatrices in the reconnection exhaust. Our observations are consistent with electron acceleration by electric fields at the separatrices. The strong correlation between the electron bursts and sudden commencements of large-amplitude electric and magnetic structures suggests that the underlying reconnection dynamics is impulsive and non-steady. Title: Average profiles of energetic and thermal electrons in the magnetotail reconnection regions Authors: Imada, S.; Hoshino, M.; Mukai, T. Bibcode: 2005GeoRL..32.9101I Altcode: 2005GeoRL..3209101I We study plasma heating and acceleration around magnetic reconnection region by using GEOTAIL data. We carry out the superposed analysis of thermal temperature and energetic electrons flux as a function of distance from X-type neutral line, for both the near-Earth and the distant magnetotail. It is found that the enhanced energetic flux and high temperature regions are located around reconnection outflow region downstream away from the center of the X-type neutral region. Those heated and accelerated regions are symmetric in both of the tail- and earth-ward flow regions in the distant magnetotail, while in the near-Earth magnetotail more energetic electrons are preferentially observed in the earthward flow region. In addition, we also study electron heating and acceleration during the passage of plasmoid, which may correspond to O-type neutral line. We find the hot and energetic electrons behind the core of plasmoid but slightly away from the central plasma sheet. Title: The Dawn-Dusk Asymmetry in Magnetosheath and the Leakage of Energetic Electrons: The Geotail Observation Authors: Imada, S.; Hoshino, M.; Mukai, T. Bibcode: 2005fmpp.conf...34I Altcode: No abstract at ADS