Author name code: domingo ADS astronomy entries on 2022-09-14 author:"Domingo, Vicente" ------------------------------------------------------------------------ Title: The Polarimetric and Helioseismic Imager on Solar Orbiter Authors: Solanki, S. K.; del Toro Iniesta, J. C.; Woch, J.; Gandorfer, A.; Hirzberger, J.; Alvarez-Herrero, A.; Appourchaux, T.; Martínez Pillet, V.; Pérez-Grande, I.; Sanchis Kilders, E.; Schmidt, W.; Gómez Cama, J. M.; Michalik, H.; Deutsch, W.; Fernandez-Rico, G.; Grauf, B.; Gizon, L.; Heerlein, K.; Kolleck, M.; Lagg, A.; Meller, R.; Müller, R.; Schühle, U.; Staub, J.; Albert, K.; Alvarez Copano, M.; Beckmann, U.; Bischoff, J.; Busse, D.; Enge, R.; Frahm, S.; Germerott, D.; Guerrero, L.; Löptien, B.; Meierdierks, T.; Oberdorfer, D.; Papagiannaki, I.; Ramanath, S.; Schou, J.; Werner, S.; Yang, D.; Zerr, A.; Bergmann, M.; Bochmann, J.; Heinrichs, J.; Meyer, S.; Monecke, M.; Müller, M. -F.; Sperling, M.; Álvarez García, D.; Aparicio, B.; Balaguer Jiménez, M.; Bellot Rubio, L. R.; Cobos Carracosa, J. P.; Girela, F.; Hernández Expósito, D.; Herranz, M.; Labrousse, P.; López Jiménez, A.; Orozco Suárez, D.; Ramos, J. L.; Barandiarán, J.; Bastide, L.; Campuzano, C.; Cebollero, M.; Dávila, B.; Fernández-Medina, A.; García Parejo, P.; Garranzo-García, D.; Laguna, H.; Martín, J. A.; Navarro, R.; Núñez Peral, A.; Royo, M.; Sánchez, A.; Silva-López, M.; Vera, I.; Villanueva, J.; Fourmond, J. -J.; de Galarreta, C. Ruiz; Bouzit, M.; Hervier, V.; Le Clec'h, J. C.; Szwec, N.; Chaigneau, M.; Buttice, V.; Dominguez-Tagle, C.; Philippon, A.; Boumier, P.; Le Cocguen, R.; Baranjuk, G.; Bell, A.; Berkefeld, Th.; Baumgartner, J.; Heidecke, F.; Maue, T.; Nakai, E.; Scheiffelen, T.; Sigwarth, M.; Soltau, D.; Volkmer, R.; Blanco Rodríguez, J.; Domingo, V.; Ferreres Sabater, A.; Gasent Blesa, J. L.; Rodríguez Martínez, P.; Osorno Caudel, D.; Bosch, J.; Casas, A.; Carmona, M.; Herms, A.; Roma, D.; Alonso, G.; Gómez-Sanjuan, A.; Piqueras, J.; Torralbo, I.; Fiethe, B.; Guan, Y.; Lange, T.; Michel, H.; Bonet, J. A.; Fahmy, S.; Müller, D.; Zouganelis, I. Bibcode: 2020A&A...642A..11S Altcode: 2019arXiv190311061S
Aims: This paper describes the Polarimetric and Helioseismic Imager on the Solar Orbiter mission (SO/PHI), the first magnetograph and helioseismology instrument to observe the Sun from outside the Sun-Earth line. It is the key instrument meant to address the top-level science question: How does the solar dynamo work and drive connections between the Sun and the heliosphere? SO/PHI will also play an important role in answering the other top-level science questions of Solar Orbiter, while hosting the potential of a rich return in further science.
Methods: SO/PHI measures the Zeeman effect and the Doppler shift in the Fe I 617.3 nm spectral line. To this end, the instrument carries out narrow-band imaging spectro-polarimetry using a tunable LiNbO3 Fabry-Perot etalon, while the polarisation modulation is done with liquid crystal variable retarders. The line and the nearby continuum are sampled at six wavelength points and the data are recorded by a 2k × 2k CMOS detector. To save valuable telemetry, the raw data are reduced on board, including being inverted under the assumption of a Milne-Eddington atmosphere, although simpler reduction methods are also available on board. SO/PHI is composed of two telescopes; one, the Full Disc Telescope, covers the full solar disc at all phases of the orbit, while the other, the High Resolution Telescope, can resolve structures as small as 200 km on the Sun at closest perihelion. The high heat load generated through proximity to the Sun is greatly reduced by the multilayer-coated entrance windows to the two telescopes that allow less than 4% of the total sunlight to enter the instrument, most of it in a narrow wavelength band around the chosen spectral line.
Results: SO/PHI was designed and built by a consortium having partners in Germany, Spain, and France. The flight model was delivered to Airbus Defence and Space, Stevenage, and successfully integrated into the Solar Orbiter spacecraft. A number of innovations were introduced compared with earlier space-based spectropolarimeters, thus allowing SO/PHI to fit into the tight mass, volume, power and telemetry budgets provided by the Solar Orbiter spacecraft and to meet the (e.g. thermal) challenges posed by the mission's highly elliptical orbit. Title: Small magnetic structures near the polar regions of the Sun Authors: Cabello, I.; Blanco Rodríguez, J.; Balmaceda, L.; Domingo, V. Bibcode: 2017IAUS..327...40C Altcode: The study of the small magnetic structures of the solar photosphere is of great relevance because of their association with concentrations of magnetic field and their possible contribution to the variations of the Total Solar Irradiance. These structures are known to appear close to active regions and ubiquitously in the quiet Sun areas. Numerous studies about their distribution across all over the solar surface have been done with high-resolution instrumentation. However, since the observations have always been carried out from the ecliptic plane, their distribution near the polar regions is not well known. Future missions, like Solar Orbiter, will certainly provide valuable information on these yet unexplored regions. In this work, and in preparation for that moment, we select favorable periods for the observation of the polar regions of the Sun, and study the fraction of covered surface by small magnetic structures and its variation with the solar activity. Title: Detección y análisis de pequeñas estructuras magnéticas en las regiones próximas a los polos solares Authors: Cabello, I.; Blanco Rodríguez, J.; Balmaceda, L.; Domingo, V. Bibcode: 2017BAAA...59..154C Altcode: The solar magnetic field plays a fundamental role in the overall behaviour of the Sun. In the solar photosphere, the magnetic field is evidenced with a wide range of structures with different sizes, shapes and intensities. Bright Points (BPs) are the smallest of these manifestations discernible with the current instruments, and their presence is observable all over the solar disk, on both active and quiet regions. However, due to difficulties in observing polar areas, the presence of BPs in these regions is poorly known so far. The Solar Orbiter mission will be launched in 2018 and will observe the Sun up to 30º outside the ecliptic, allowing the analysis of BPs appearance in areas close to the solar poles. A preliminar study can be done considering the inclination of the ecliptic plane relative to the solar axis, so that these regions can be observed at certain times in the year. In this work, G-band images have been used to detect and analyse BPs located in areas close to the solar poles. Title: Multi-wavelength observations of vortex-like flows in the photosphere using ground-based and space-borne telescopes Authors: Palacios, J.; Vargas Domínguez, S.; Balmaceda, L. A.; Cabello, I.; Domingo, V. Bibcode: 2017arXiv170400660P Altcode: In this work we follow a series of papers on high-resolution observations of small-scale structures in the solar atmosphere \citep[][Cabello et al., in prep]{Balmaceda2009, Balmaceda2010, Vargas2011, Palacios2012, Domingo2012, Vargas2015}, combining several multi-wavelength data series. These were acquired by both ground-based (SST) and space-borne (Hinode) instruments during the joint campaign of the Hinode Operation Program 14, in September 2007. Diffraction-limited SST data were taken in the G-band and G-cont, and were restored by the MFBD technique. Hinode instruments, on the other hand, provided multispectral data from SOT-FG in the CN band, and Mg~{\sc I} and Ca {\sc II}~lines, as well as from SOT-SP in the Fe~{\sc I} line. In this series of works we have thoroughly studied vortex flows and their statistical occurrences, horizontal velocity fields by means of Local Correlation Tracking (LCT), divergence and vorticity. Taking advantage of the high-cadence and high spatial resolution data, we have also studied bright point statistics and magnetic field intensification, highlighting the importance of the smallest-scale magnetic element observations. Title: Multi-wavelength Observations of Photospheric Vortex Flows in the Photosphere Using Ground-based and Space-borne Telescopes Authors: Palacios, J.; Vargas Domínguez, S.; Balmaceda, L. A.; Cabello, I.; Domingo, V. Bibcode: 2016ASPC..504..139P Altcode: In this work we follow a series of papers on high-resolution observations of small-scale structures in the solar atmosphere (Balmaceda et al. 2009, 2010; Vargas Domínguez et al. 2011; Palacios et al. 2012; Domingo et al. 2012; Vargas Domínguez et al. 2015, Cabello et al., in prep), combining several multi-wavelength data series. These were acquired by both ground-based (SST) and space-borne (Hinode) instruments during the joint campaign of the Hinode Operation Program 14, in September 2007. Diffraction-limited SST data were taken in the G-band and G-cont, and were restored by the MFBD technique. Hinode instruments, on the other hand, provided multispectral data from SOT-FG in the CN band, and Mg I and Ca II lines, as well as from SOT-SP in the Fe I line. In this series of works we have thoroughly studied vortex flows and their statistical occurrences, horizontal velocity fields by means of Local Correlation Tracking (LCT), divergence and vorticity. Taking advantage of the high-cadence and high spatial resolution data, we have also studied bright point statistics and magnetic field intensification, highlighting the importance of the smallest-scale magnetic element observations. Title: Influence of a plasma swirl motion on fine magnetic concentrations in the solar photosphere Authors: Palacios, Judith; Balmaceda, Laura; Cabello, Iballa; Domingo, Vicente Bibcode: 2016Tecci..11....1P Altcode: High-resolution observations from ground-based (Solar Swedish Telescope) and space-borne (Hinode) solar telescopes acquired data with various filters, obtaining images of a quiet Sun region populated with small-scale magnetic elements. The region is also characterized by the presence of photospheric swirl convective plasma structures. This work abridges the results of different analyses applied over time series of images to follow the evolution of magnetic features aiming to establish the influence of the plasma vortices on their motions. Title: Evolution of Small-Scale Magnetic Elements in the Vicinity of Granular-Sized Swirl Convective Motions Authors: Vargas Domínguez, S.; Palacios, J.; Balmaceda, L.; Cabello, I.; Domingo, V. Bibcode: 2015SoPh..290..301V Altcode: 2014SoPh..tmp..187V; 2014arXiv1405.2380V Advances in solar instrumentation have led to widespread use of time series to study the dynamics of solar features, especially at small spatial scales and at very fast cadences. Physical processes at such scales are important as building blocks for many other processes occurring from the lower to the upper layers of the solar atmosphere and beyond, ultimately for understanding the larger picture of solar activity. Ground-based (Swedish Solar Telescope) and space-borne (Hinode) high-resolution solar data are analyzed in a quiet-Sun region that displays negative-polarity small-scale magnetic concentrations and a cluster of bright points observed in G-band. The region is characterized by two granular-sized convective vortex-type plasma motions, one of which appears to be affecting the dynamics of magnetic features and bright points in its vicinity and is therefore the main target of our investigations. We followed the evolution of the bright points, intensity variations at different atmospheric height, and the magnetic evolution for a set of interesting selected regions. We describe the evolution of the photospheric plasma motions in the region near the convective vortex and some plausible cases for convective collapse detected in Stokes profiles. Title: Magnetic evolution of faculae observed with IMaX Authors: Blanco, J.; Palacios, J.; Cabello, I.; Domingo, V.; Sunrise Team Bibcode: 2013hsa7.conf..803B Altcode: The SUNRISE mission, consisting of a one metre diameter telescope on board a stratospheric balloon, was launched on June 2009 on route over the artic circle. At approximately 36 km height, the balloon flight allowed to observe with almost no atmospheric influence yielding very good quality data as well as observations in ultraviolet spectral lines (by means of the SUFI instrument). The mission's artic summer-circumpolar flight path provided continuous solar observations, without day-night cycles, during the almost 5 days of the mission. IMaX/SUNRISE instrument --developed by a consortium of Spanish institutions-- is a spectropolarimeter based in the use of a Fabry-Pérot etalon and liquid crystals for spectral and polarimetric analysis, respectively. It obtained full-Stokes vector maps at the selected wavelength of Fe I 5250.2 Å with a temporal cadence of around 30 seconds and a spatial resolution of approximately 0.15--0.18 arcsec. In this poster, we present a temporal series of a group of limb faculae comprising approximately 21 minutes. Thanks to the data quality, as well as the full-Stokes maps and fast temporal cadence, small-scale magnetic cancellations and emergences can be observed around and at the faculae positions. We focused on a small area of the instrument field of view where the cancellation magnetogram shows high magnetic polarity changes. What we observe are confronted patches of opposite polarities from the longitudinal magnetic field, being cancelled and reappearing, while the transversal field signal present changes also accordingly. This reflects as well in the continuum intensity images where facular brightenings are seen enhancing and decreasing in consonance with the transversal field evolution. Studies of this cancellation phenomena and evolution of the facular structures as magnetic tubes are being performed for more thorough analyses. Title: Study of small magnetic structures in the solar photosphere Authors: Cabello, I.; Domingo, V.; Bonet, J. A.; Blanco Rodríguez, J.; Balmaceda, L. A. Bibcode: 2013hsa7.conf..805C Altcode: The study of small scale magnetic structures in the solar photosphere is of great relevance for the understanding of the global behaviour of the Sun. Because of the small spatial and temporal scales involved, the use of high resolution images and fast cadence is fundamental for their study. In order to obtain such images, sophisticated computational techniques that compensate for the atmospheric degradation and telescope aberration have been developed, improving in this way the spatial resolution. In this work, we use G-band images obtained with the 1 m-Swedish Solar Telescope located at La Palma (Canary Islands, Spain). The images have been restored with MOMFBD (Multi-Object Multi-Frame Blind Deconvolution), a technique that combines multiple images acquired in a short time interval. The resulting images have a resolution close to the diffraction limit of the telescope (0.1 arcsec) allowing the study of very small bright structures present in the inter-granular lanes in the solar photosphere, known as Bright Points. It is highlighted the great presence of magnetic structures in quiet Sun regions analyzed from different observational campaigns. The density of BPs in the quiet Sun shows a decrease as we approach the limb, with values of ≃q 1% at the centre (μ ≈ 1), and ≃q 0.2% at μ ≈ 0.3. We also present the discovery of small vortexes detected in the solar surface through the movement of BPs, with radii around 241 km and lifetimes longer than 5 minutes. Further analyses, comprising longer time series and information from different solar layers, are being performed aiming at a more in-depth knowledge of these phenomena. Title: Small magnetic bright structures in the quiet Sun Authors: Domingo, V.; Cabello, I.; Blanco Rodríguez, J. Bibcode: 2013hsa7.conf..782D Altcode: This work aims at further developing our knowledge of the ubiquitous small scale magnetic structures of the solar surface, focusing on the poles of the Sun. To get a clearer view of the situation at the very high latitudes, we make use of the inclination of the solar axis with respect to the ecliptic. We find the known continuous decrease of the area covered by bright points from centre to limb. However, when the solar rotation axis is inclined toward us there is an increase in bright points areas coverage near the limb, i.e. near the poles. Title: Structure of Small Magnetic Elements in the Solar Atmosphere Authors: Domingo, V.; Palacios, J.; Balmaceda, L. A.; Domínguez, S. V.; Cabello, I. Bibcode: 2012ASPC..454...69D Altcode: 2012arXiv1209.0978D High resolution images at different wavelengths, spectrograms and magnetograms, representing different levels of the solar atmosphere obtained with Hinode have been combined to study the 3-dimensional structure of the small magnetic elements in relation to their radiance. A small magnetic element is described as example of the study. Title: Observations of Vortex Motion in the Solar Photosphere Using Hinode-SP Data Authors: Palacios, J.; Balmaceda, L. A.; Domínguez, S. V.; Cabello, I.; Domingo, V. Bibcode: 2012ASPC..454...51P Altcode: 2012arXiv1209.0190P In this work, we focus in the magnetic evolution of a small region as seen by Hinode-SP during the time interval of about one hour. High-cadence LOS magnetograms and velocity maps were derived, allowing the study of different small-scale processes such as the formation/dissappearance of bright points accompanying the evolution of an observed convective vortical motion. Title: First Results from the SUNRISE Mission Authors: Solanki, S. K.; Barthol, P.; Danilovic, S.; Feller, A.; Gandorfer, A.; Hirzberger, J.; Jafarzadeh, S.; Lagg, A.; Riethmüller, T. L.; Schüssler, M.; Wiegelmann, T.; Bonet, J. A.; González, M. J. M.; Pillet, V. M.; Khomenko, E.; Yelles Chaouche, L.; Iniesta, J. C. d. T.; Domingo, V.; Palacios, J.; Knölker, M.; González, N. B.; Borrero, J. M.; Berkefeld, T.; Franz, M.; Roth, M.; Schmidt, W.; Steiner, O.; Title, A. M. Bibcode: 2012ASPC..455..143S Altcode: The SUNRISE balloon-borne solar observatory consists of a 1m aperture Gregory telescope, a UV filter imager, an imaging vector polarimeter, an image stabilization system, and further infrastructure. The first science flight of SUNRISE yielded high-quality data that reveal the structure, dynamics, and evolution of solar convection, oscillations, and magnetic fields at a resolution of around 100 km in the quiet Sun. Here we describe very briefly the mission and the first results obtained from the SUNRISE data, which include a number of discoveries. Title: Detection of Vortex Tubes in Solar Granulation from Observations SUNRISE Authors: Steiner, O.; Franz, M.; González, N. B.; Nutto, C.; Rezaei, R.; Pillet, V. M.; Bonet, J. A.; Iniesta, J. C. d. T.; Domingo, V.; Solanki, S. K.; Knölker, M.; Schmidt, W.; Barthol, P.; Gandorfer, A. Bibcode: 2012ASPC..455...35S Altcode: We investigated a time series of continuum intensity maps and Dopplergrams of granulation in a very quiet solar region at the disk center, recorded with the Imaging Magnetograph eXperiment (IMaX) on board the balloon-borne solar observatory SUNRISE. We find that granules frequently show substructure in the form of lanes composed of a leading bright rim and a trailing dark edge, which move together from the boundary of a granule into the granule itself. We find strikingly similar events in synthesized intensity maps from an ab initio numerical simulation of solar surface convection. We conclude that these granular lanes are the visible signature of (horizontally oriented) vortex tubes. The characteristic optical appearance of vortex tubes at the solar surface is explained. This paper is a summary and update of the results previously presented in Steiner et al. (2010). Title: Supersonic Magnetic Flows in the Quiet Sun Observed with SUNRISE/IMaX Authors: Borrero, J. M.; Pillet, V. M.; Schlichenmaier, R.; Schmidt, W.; Berkefeld, T.; Solanki, S. K.; Bonet, J. A.; Iniesta, J. C. d. T.; Domingo, V.; Barthol, P.; Gandorfer, A. Bibcode: 2012ASPC..455..155B Altcode: 2012arXiv1202.4354B In this contribution we describe some recent observations of high-speed magnetized flows in the quiet Sun granulation. These observations were carried out with the Imaging Magnetograph eXperiment (IMaX) onboard the stratospheric balloon SUNRISE, and possess an unprecedented spatial resolution and temporal cadence. These flows were identified as highly shifted circular polarization (Stokes V) signals. We estimate the LOS velocity responsible for these shifts to be larger than 6 km s-1, and therefore we refer to them as supersonic magnetic flows. The average lifetime of the detected events is 81.3 s and they occupy an average area of about 23 000 km2. Most of the events occur within granular cells and correspond therefore to upflows. However some others occur in intergranular lanes or bear no clear relation to the convective velocity pattern. We analyze a number of representative examples and discuss them in terms of magnetic loops, reconnection events, and convective collapse. Title: Actinide and Ultra-Heavy Abundances in the Local Galactic Cosmic Rays: An Analysis of the Results from the LDEF Ultra-Heavy Cosmic-Ray Experiment Authors: Donnelly, J.; Thompson, A.; O'Sullivan, D.; Daly, J.; Drury, L.; Domingo, V.; Wenzel, K. -P. Bibcode: 2012ApJ...747...40D Altcode: The LDEF Ultra-Heavy Cosmic-Ray Experiment (UHCRE) detected Galactic cosmic rays (GCRs) of charge Z >= 70 in Earth orbit with an exposure factor of 170 m2 sr yr, much larger than any other experiment. The major results include the first statistically significant uniform sample of GCR actinides with 35 events passing quality cuts, evidence for the existence of transuranic nuclei in the GCR with one 96Cm candidate event, and a low 82Pb/78Pt ratio consistent with other experiments. The probability of the existence of a transuranic component is estimated as 96%, while the most likely 92U/90Th ratio is found to be 0.4 within a wide 70% confidence interval ranging from 0 to 0.96. Overall, the results are consistent with a volatility-based acceleration bias and source material which is mainly ordinary interstellar medium material with some recent contamination by freshly synthesized material. Uncertainty in the key 92U/90Th ratio is dominated by statistical errors resulting from the small sample size and any improved determination will thus require an experiment with a substantially larger exposure factor than the UHCRE. Title: Magnetic field emergence in mesogranular-sized exploding granules observed with sunrise/IMaX data Authors: Palacios, J.; Blanco Rodríguez, J.; Vargas Domínguez, S.; Domingo, V.; Martínez Pillet, V.; Bonet, J. A.; Bellot Rubio, L. R.; Del Toro Iniesta, J. C.; Solanki, S. K.; Barthol, P.; Gandorfer, A.; Berkefeld, T.; Schmidt, W.; Knölker, M. Bibcode: 2012A&A...537A..21P Altcode: 2011arXiv1110.4555P We report on magnetic field emergences covering significant areas of exploding granules. The balloon-borne mission Sunrise provided high spatial and temporal resolution images of the solar photosphere. Continuum images, longitudinal and transverse magnetic field maps and Dopplergrams obtained by IMaX onboard Sunrise are analyzed by local correlation traking (LCT), divergence calculation and time slices, Stokes inversions and numerical simulations are also employed. We characterize two mesogranular-scale exploding granules where ~1018 Mx of magnetic flux emerges. The emergence of weak unipolar longitudinal fields (~100 G) start with a single visible magnetic polarity, occupying their respective granules' top and following the granular splitting. After a while, mixed polarities start appearing, concentrated in downflow lanes. The events last around 20 min. LCT analyses confirm mesogranular scale expansion, displaying a similar pattern for all the physical properties, and divergence centers match between all of them. We found a similar behaviour with the emergence events in a numerical MHD simulation. Granule expansion velocities are around 1 kms-1 while magnetic patches expand at 0.65 kms-1. One of the analyzed events evidences the emergence of a loop-like structure. Advection of the emerging magnetic flux features is dominated by convective motion resulting from the exploding granule due to the magnetic field frozen in the granular plasma. Intensification of the magnetic field occurs in the intergranular lanes, probably because of being directed by the downflowing plasma.

Movies associated to Figs. 2-4 are available in electronic form at http://www.aanda.org Title: Spatial distribution and statistical properties of small-scale convective vortex-like motions in a quiet-Sun region Authors: Vargas Domínguez, S.; Palacios, J.; Balmaceda, L.; Cabello, I.; Domingo, V. Bibcode: 2011MNRAS.416..148V Altcode: 2011MNRAS.tmp.1046V; 2011arXiv1105.3092V High-resolution observations of a quiet-Sun internetwork region taken with the Solar 1-m Swedish Telescope in La Palma are analysed. We determine the location of small-scale vortex motions in the solar photospheric region by computing the horizontal proper motions of small-scale structures on time-series of images. These plasma convectively driven swirl motions are associated to (1) downdrafts (that have been commonly explained as corresponding to sites where the plasma is cooled down and hence returned to the interior below the visible photospheric level) and (2) horizontal velocity vectors converging on a central point. The sink cores are proved to be the final destination of passive floats tracing plasma flows towards the centre of each vortex. We establish the occurrence of these events to be 1.4 × 10-3 and 1.6 × 10-3 vortices Mm-2 min-1, respectively, for the two time-series analysed here. Title: The Sun at high resolution: first results from the Sunrise mission Authors: Solanki, S. K.; Barthol, P.; Danilovic, S.; Feller, A.; Gandorfer, A.; Hirzberger, J.; Lagg, A.; Riethmüller, T. L.; Schüssler, M.; Wiegelmann, T.; Bonet, J. A.; Pillet, V. Martínez; Khomenko, E.; del Toro Iniesta, J. C.; Domingo, V.; Palacios, J.; Knölker, M.; González, N. Bello; Borrero, J. M.; Berkefeld, T.; Franz, M.; Roth, M.; Schmidt, W.; Steiner, O.; Title, A. M. Bibcode: 2011IAUS..273..226S Altcode: The Sunrise balloon-borne solar observatory consists of a 1m aperture Gregory telescope, a UV filter imager, an imaging vector polarimeter, an image stabilization system and further infrastructure. The first science flight of Sunrise yielded high-quality data that reveal the structure, dynamics and evolution of solar convection, oscillations and magnetic fields at a resolution of around 100 km in the quiet Sun. Here we describe very briefly the mission and the first results obtained from the Sunrise data, which include a number of discoveries. Title: The Imaging Magnetograph eXperiment (IMaX) for the Sunrise Balloon-Borne Solar Observatory Authors: Martínez Pillet, V.; del Toro Iniesta, J. C.; Álvarez-Herrero, A.; Domingo, V.; Bonet, J. A.; González Fernández, L.; López Jiménez, A.; Pastor, C.; Gasent Blesa, J. L.; Mellado, P.; Piqueras, J.; Aparicio, B.; Balaguer, M.; Ballesteros, E.; Belenguer, T.; Bellot Rubio, L. R.; Berkefeld, T.; Collados, M.; Deutsch, W.; Feller, A.; Girela, F.; Grauf, B.; Heredero, R. L.; Herranz, M.; Jerónimo, J. M.; Laguna, H.; Meller, R.; Menéndez, M.; Morales, R.; Orozco Suárez, D.; Ramos, G.; Reina, M.; Ramos, J. L.; Rodríguez, P.; Sánchez, A.; Uribe-Patarroyo, N.; Barthol, P.; Gandorfer, A.; Knoelker, M.; Schmidt, W.; Solanki, S. K.; Vargas Domínguez, S. Bibcode: 2011SoPh..268...57M Altcode: 2010SoPh..tmp..181M; 2010arXiv1009.1095M The Imaging Magnetograph eXperiment (IMaX) is a spectropolarimeter built by four institutions in Spain that flew on board the Sunrise balloon-borne solar observatory in June 2009 for almost six days over the Arctic Circle. As a polarimeter, IMaX uses fast polarization modulation (based on the use of two liquid crystal retarders), real-time image accumulation, and dual-beam polarimetry to reach polarization sensitivities of 0.1%. As a spectrograph, the instrument uses a LiNbO3 etalon in double pass and a narrow band pre-filter to achieve a spectral resolution of 85 mÅ. IMaX uses the high-Zeeman-sensitive line of Fe I at 5250.2 Å and observes all four Stokes parameters at various points inside the spectral line. This allows vector magnetograms, Dopplergrams, and intensity frames to be produced that, after reconstruction, reach spatial resolutions in the 0.15 - 0.18 arcsec range over a 50×50 arcsec field of view. Time cadences vary between 10 and 33 s, although the shortest one only includes longitudinal polarimetry. The spectral line is sampled in various ways depending on the applied observing mode, from just two points inside the line to 11 of them. All observing modes include one extra wavelength point in the nearby continuum. Gauss equivalent sensitivities are 4 G for longitudinal fields and 80 G for transverse fields per wavelength sample. The line-of-sight velocities are estimated with statistical errors of the order of 5 - 40 m s−1. The design, calibration, and integration phases of the instrument, together with the implemented data reduction scheme, are described in some detail. Title: The Sunrise Mission Authors: Barthol, P.; Gandorfer, A.; Solanki, S. K.; Schüssler, M.; Chares, B.; Curdt, W.; Deutsch, W.; Feller, A.; Germerott, D.; Grauf, B.; Heerlein, K.; Hirzberger, J.; Kolleck, M.; Meller, R.; Müller, R.; Riethmüller, T. L.; Tomasch, G.; Knölker, M.; Lites, B. W.; Card, G.; Elmore, D.; Fox, J.; Lecinski, A.; Nelson, P.; Summers, R.; Watt, A.; Martínez Pillet, V.; Bonet, J. A.; Schmidt, W.; Berkefeld, T.; Title, A. M.; Domingo, V.; Gasent Blesa, J. L.; del Toro Iniesta, J. C.; López Jiménez, A.; Álvarez-Herrero, A.; Sabau-Graziati, L.; Widani, C.; Haberler, P.; Härtel, K.; Kampf, D.; Levin, T.; Pérez Grande, I.; Sanz-Andrés, A.; Schmidt, E. Bibcode: 2011SoPh..268....1B Altcode: 2010arXiv1009.2689B; 2010SoPh..tmp..224B The first science flight of the balloon-borne Sunrise telescope took place in June 2009 from ESRANGE (near Kiruna/Sweden) to Somerset Island in northern Canada. We describe the scientific aims and mission concept of the project and give an overview and a description of the various hardware components: the 1-m main telescope with its postfocus science instruments (the UV filter imager SuFI and the imaging vector magnetograph IMaX) and support instruments (image stabilizing and light distribution system ISLiD and correlating wavefront sensor CWS), the optomechanical support structure and the instrument mounting concept, the gondola structure and the power, pointing, and telemetry systems, and the general electronics architecture. We also explain the optimization of the structural and thermal design of the complete payload. The preparations for the science flight are described, including AIV and ground calibration of the instruments. The course of events during the science flight is outlined, up to the recovery activities. Finally, the in-flight performance of the instrumentation is discussed. Title: SUNRISE: Instrument, Mission, Data, and First Results Authors: Solanki, S. K.; Barthol, P.; Danilovic, S.; Feller, A.; Gandorfer, A.; Hirzberger, J.; Riethmüller, T. L.; Schüssler, M.; Bonet, J. A.; Martínez Pillet, V.; del Toro Iniesta, J. C.; Domingo, V.; Palacios, J.; Knölker, M.; Bello González, N.; Berkefeld, T.; Franz, M.; Schmidt, W.; Title, A. M. Bibcode: 2010ApJ...723L.127S Altcode: 2010arXiv1008.3460S The SUNRISE balloon-borne solar observatory consists of a 1 m aperture Gregory telescope, a UV filter imager, an imaging vector polarimeter, an image stabilization system, and further infrastructure. The first science flight of SUNRISE yielded high-quality data that revealed the structure, dynamics, and evolution of solar convection, oscillations, and magnetic fields at a resolution of around 100 km in the quiet Sun. After a brief description of instruments and data, the first qualitative results are presented. In contrast to earlier observations, we clearly see granulation at 214 nm. Images in Ca II H display narrow, short-lived dark intergranular lanes between the bright edges of granules. The very small-scale, mixed-polarity internetwork fields are found to be highly dynamic. A significant increase in detectable magnetic flux is found after phase-diversity-related reconstruction of polarization maps, indicating that the polarities are mixed right down to the spatial resolution limit and probably beyond. Title: Supersonic Magnetic Upflows in Granular Cells Observed with SUNRISE/IMAX Authors: Borrero, J. M.; Martínez-Pillet, V.; Schlichenmaier, R.; Solanki, S. K.; Bonet, J. A.; del Toro Iniesta, J. C.; Schmidt, W.; Barthol, P.; Gandorfer, A.; Domingo, V.; Knölker, M. Bibcode: 2010ApJ...723L.144B Altcode: 2010arXiv1009.1227B Using the IMaX instrument on board the SUNRISE stratospheric balloon telescope, we have detected extremely shifted polarization signals around the Fe I 5250.217 Å spectral line within granules in the solar photosphere. We interpret the velocities associated with these events as corresponding to supersonic and magnetic upflows. In addition, they are also related to the appearance of opposite polarities and highly inclined magnetic fields. This suggests that they are produced by the reconnection of emerging magnetic loops through granular upflows. The events occupy an average area of 0.046 arcsec2 and last for about 80 s, with larger events having longer lifetimes. These supersonic events occur at a rate of 1.3 × 10-5 occurrences per second per arcsec2. Title: Detection of Vortex Tubes in Solar Granulation from Observations with SUNRISE Authors: Steiner, O.; Franz, M.; Bello González, N.; Nutto, Ch.; Rezaei, R.; Martínez Pillet, V.; Bonet Navarro, J. A.; del Toro Iniesta, J. C.; Domingo, V.; Solanki, S. K.; Knölker, M.; Schmidt, W.; Barthol, P.; Gandorfer, A. Bibcode: 2010ApJ...723L.180S Altcode: 2010arXiv1009.4723S We have investigated a time series of continuum intensity maps and corresponding Dopplergrams of granulation in a very quiet solar region at the disk center, recorded with the Imaging Magnetograph eXperiment (IMaX) on board the balloon-borne solar observatory SUNRISE. We find that granules frequently show substructure in the form of lanes composed of a leading bright rim and a trailing dark edge, which move together from the boundary of a granule into the granule itself. We find strikingly similar events in synthesized intensity maps from an ab initio numerical simulation of solar surface convection. From cross sections through the computational domain of the simulation, we conclude that these granular lanes are the visible signature of (horizontally oriented) vortex tubes. The characteristic optical appearance of vortex tubes at the solar surface is explained. We propose that the observed vortex tubes may represent only the large-scale end of a hierarchy of vortex tubes existing near the solar surface. Title: Where the Granular Flows Bend Authors: Khomenko, E.; Martínez Pillet, V.; Solanki, S. K.; del Toro Iniesta, J. C.; Gandorfer, A.; Bonet, J. A.; Domingo, V.; Schmidt, W.; Barthol, P.; Knölker, M. Bibcode: 2010ApJ...723L.159K Altcode: 2010arXiv1008.0517K Based on IMaX/SUNRISE data, we report on a previously undetected phenomenon in solar granulation. We show that in a very narrow region separating granules and intergranular lanes, the spectral line width of the Fe I 5250.2 Å line becomes extremely small. We offer an explanation of this observation with the help of magneto-convection simulations. These regions with extremely small line widths correspond to the places where the granular flows bend from upflow in granules to downflow in intergranular lanes. We show that the resolution and image stability achieved by IMaX/SUNRISE are important requisites to detect this interesting phenomenon. Title: Bright Points in the Quiet Sun as Observed in the Visible and Near-UV by the Balloon-borne Observatory SUNRISE Authors: Riethmüller, T. L.; Solanki, S. K.; Martínez Pillet, V.; Hirzberger, J.; Feller, A.; Bonet, J. A.; Bello González, N.; Franz, M.; Schüssler, M.; Barthol, P.; Berkefeld, T.; del Toro Iniesta, J. C.; Domingo, V.; Gandorfer, A.; Knölker, M.; Schmidt, W. Bibcode: 2010ApJ...723L.169R Altcode: 2010arXiv1009.1693R Bright points (BPs) are manifestations of small magnetic elements in the solar photosphere. Their brightness contrast not only gives insight into the thermal state of the photosphere (and chromosphere) in magnetic elements, but also plays an important role in modulating the solar total and spectral irradiance. Here, we report on simultaneous high-resolution imaging and spectropolarimetric observations of BPs using SUNRISE balloon-borne observatory data of the quiet Sun at the disk center. BP contrasts have been measured between 214 nm and 525 nm, including the first measurements at wavelengths below 388 nm. The histograms of the BP peak brightness show a clear trend toward broader contrast distributions and higher mean contrasts at shorter wavelengths. At 214 nm, we observe a peak brightness of up to five times the mean quiet-Sun value, the highest BP contrast so far observed. All BPs are associated with a magnetic signal, although in a number of cases it is surprisingly weak. Most of the BPs show only weak downflows, the mean value being 240 m s-1, but some display strong down- or upflows reaching a few km s-1. Title: Transverse Component of the Magnetic Field in the Solar Photosphere Observed by SUNRISE Authors: Danilovic, S.; Beeck, B.; Pietarila, A.; Schüssler, M.; Solanki, S. K.; Martínez Pillet, V.; Bonet, J. A.; del Toro Iniesta, J. C.; Domingo, V.; Barthol, P.; Berkefeld, T.; Gandorfer, A.; Knölker, M.; Schmidt, W.; Title, A. M. Bibcode: 2010ApJ...723L.149D Altcode: 2010arXiv1008.1535D We present the first observations of the transverse component of a photospheric magnetic field acquired by the imaging magnetograph SUNRISE/IMaX. Using an automated detection method, we obtain statistical properties of 4536 features with significant linear polarization signal. We obtain a rate of occurrence of 7 × 10-4 s-1 arcsec-2, which is 1-2 orders of magnitude larger than the values reported by previous studies. We show that these features have no characteristic size or lifetime. They appear preferentially at granule boundaries with most of them being caught in downflow lanes at some point. Only a small percentage are entirely and constantly embedded in upflows (16%) or downflows (8%). Title: Detection of Large Acoustic Energy Flux in the Solar Atmosphere Authors: Bello González, N.; Franz, M.; Martínez Pillet, V.; Bonet, J. A.; Solanki, S. K.; del Toro Iniesta, J. C.; Schmidt, W.; Gandorfer, A.; Domingo, V.; Barthol, P.; Berkefeld, T.; Knölker, M. Bibcode: 2010ApJ...723L.134B Altcode: 2010arXiv1009.4795B We study the energy flux carried by acoustic waves excited by convective motions at sub-photospheric levels. The analysis of high-resolution spectropolarimetric data taken with IMaX/SUNRISE provides a total energy flux of ~6400-7700 W m-2 at a height of ~250 km in the 5.2-10 mHz range, i.e., at least twice the largest energy flux found in previous works. Our estimate lies within a factor of two of the energy flux needed to balance radiative losses from the chromosphere according to the estimates of Anderson & Athay and revives interest in acoustic waves for transporting energy to the chromosphere. The acoustic flux is mainly found in the intergranular lanes but also in small rapidly evolving granules and at the bright borders, forming dark dots and lanes of splitting granules. Title: Magnetic Loops in the Quiet Sun Authors: Wiegelmann, T.; Solanki, S. K.; Borrero, J. M.; Martínez Pillet, V.; del Toro Iniesta, J. C.; Domingo, V.; Bonet, J. A.; Barthol, P.; Gandorfer, A.; Knölker, M.; Schmidt, W.; Title, A. M. Bibcode: 2010ApJ...723L.185W Altcode: 2010arXiv1009.4715W We investigate the fine structure of magnetic fields in the atmosphere of the quiet Sun. We use photospheric magnetic field measurements from SUNRISE/IMaX with unprecedented spatial resolution to extrapolate the photospheric magnetic field into higher layers of the solar atmosphere with the help of potential and force-free extrapolation techniques. We find that most magnetic loops that reach into the chromosphere or higher have one footpoint in relatively strong magnetic field regions in the photosphere. Ninety-one percent of the magnetic energy in the mid-chromosphere (at a height of 1 Mm) is in field lines, whose stronger footpoint has a strength of more than 300 G, i.e., above the equipartition field strength with convection. The loops reaching into the chromosphere and corona are also found to be asymmetric in the sense that the weaker footpoint has a strength B < 300 G and is located in the internetwork (IN). Such loops are expected to be strongly dynamic and have short lifetimes, as dictated by the properties of the IN fields. Title: SUNRISE/IMaX Observations of Convectively Driven Vortex Flows in the Sun Authors: Bonet, J. A.; Márquez, I.; Sánchez Almeida, J.; Palacios, J.; Martínez Pillet, V.; Solanki, S. K.; del Toro Iniesta, J. C.; Domingo, V.; Berkefeld, T.; Schmidt, W.; Gandorfer, A.; Barthol, P.; Knölker, M. Bibcode: 2010ApJ...723L.139B Altcode: 2010arXiv1009.1992B We characterize the observational properties of the convectively driven vortex flows recently discovered on the quiet Sun, using magnetograms, Dopplergrams, and images obtained with the 1 m balloon-borne SUNRISE telescope. By visual inspection of time series, we find some 3.1 × 10-3 vortices Mm-2 minute-1, which is a factor of ~1.7 larger than previous estimates. The mean duration of the individual events turns out to be 7.9 minutes, with a standard deviation of 3.2 minutes. In addition, we find several events appearing at the same locations along the duration of the time series (31.6 minutes). Such recurrent vortices show up in the proper motion flow field map averaged over the time series. The typical vertical vorticities are lsim6 × 10-3 s-1, which corresponds to a period of rotation of some 35 minutes. The vortices show a preferred counterclockwise sense of rotation, which we conjecture may have to do with the preferred vorticity impinged by the solar differential rotation. Title: Surface Waves in Solar Granulation Observed with SUNRISE Authors: Roth, M.; Franz, M.; Bello González, N.; Martínez Pillet, V.; Bonet, J. A.; Gandorfer, A.; Barthol, P.; Solanki, S. K.; Berkefeld, T.; Schmidt, W.; del Toro Iniesta, J. C.; Domingo, V.; Knölker, M. Bibcode: 2010ApJ...723L.175R Altcode: 2010arXiv1009.4790R Solar oscillations are expected to be excited by turbulent flows in the intergranular lanes near the solar surface. Time series recorded by the IMaX instrument on board the SUNRISE observatory reveal solar oscillations at high spatial resolution, which allow the study of the properties of oscillations with short wavelengths. We analyze two time series with synchronous recordings of Doppler velocity and continuum intensity images with durations of 32 minutes and 23 minutes, respectively, recorded close to the disk center of the Sun to study the propagation and excitation of solar acoustic oscillations. In the Doppler velocity data, both the standing acoustic waves and the short-lived, high-degree running waves are visible. The standing waves are visible as temporary enhancements of the amplitudes of the large-scale velocity field due to the stochastic superposition of the acoustic waves. We focus on the high-degree small-scale waves by suitable filtering in the Fourier domain. Investigating the propagation and excitation of f- and p 1-modes with wavenumbers k>1.4 Mm-1, we also find that exploding granules contribute to the excitation of solar p-modes in addition to the contribution of intergranular lanes. Title: Fully Resolved Quiet-Sun Magnetic flux Tube Observed with the SUNRISE/IMAX Instrument Authors: Lagg, A.; Solanki, S. K.; Riethmüller, T. L.; Martínez Pillet, V.; Schüssler, M.; Hirzberger, J.; Feller, A.; Borrero, J. M.; Schmidt, W.; del Toro Iniesta, J. C.; Bonet, J. A.; Barthol, P.; Berkefeld, T.; Domingo, V.; Gandorfer, A.; Knölker, M.; Title, A. M. Bibcode: 2010ApJ...723L.164L Altcode: 2010arXiv1009.0996L Until today, the small size of magnetic elements in quiet-Sun areas has required the application of indirect methods, such as the line-ratio technique or multi-component inversions, to infer their physical properties. A consistent match to the observed Stokes profiles could only be obtained by introducing a magnetic filling factor that specifies the fraction of the observed pixel filled with magnetic field. Here, we investigate the properties of a small magnetic patch in the quiet Sun observed with the IMaX magnetograph on board the balloon-borne telescope SUNRISE with unprecedented spatial resolution and low instrumental stray light. We apply an inversion technique based on the numerical solution of the radiative transfer equation to retrieve the temperature stratification and the field strength in the magnetic patch. The observations can be well reproduced with a one-component, fully magnetized atmosphere with a field strength exceeding 1 kG and a significantly enhanced temperature in the mid to upper photosphere with respect to its surroundings, consistent with semi-empirical flux tube models for plage regions. We therefore conclude that, within the framework of a simple atmospheric model, the IMaX measurements resolve the observed quiet-Sun flux tube. Title: The IMaX polarimeter for the solar telescope SUNRISE of the NASA long duration balloon program Authors: Alvarez-Herrero, A.; Martínez-Pillet, V.; Del Toro Iniesta, J. C.; Domingo, V. Bibcode: 2010EPJWC...505002A Altcode: On June 8th 2009 the SUNRISE mission was successfully launched. This mission consisted of a 1m aperture solar telescope on board of a stratospheric balloon within the Long Duration Balloon NASA program. The flight followed the foreseen circumpolar trajectory over the Artic and the duration was 5 days and 17 hours. One of the two postfocal instruments onboard was IMaX, the Imaging Magnetograph eXperiment. This instrument is a solar magnetograph which is a diffraction limited imager capable to resolve 100 km on the solar surface, and simultaneously a high sensitivity polarimeter (<10-3) and a high resolution spectrograph (bandwidth <70mÅ). The magnetic vectorial map can be extracted thanks to the well-know Zeeman effect, which takes place in the solar atoms, allowing to relate polarization and spectral measurements to magnetic fields. The technological challenge of the IMaX development has a special relevance due to the utilization of innovative technologies in the Aeroespacial field and it is an important precedent for future space missions such as Solar Orbiter from ESA. Among these novel technologies the utilization of Liquid Crystal Variable Retarders (LCVRs) as polarization modulators and a LiNbO3 etalon as tunable spectral filter are remarkable. Currently the data obtained is being analyzed and the preliminary results show unprecedented information about the solar dynamics. Title: Evidence of small-scale magnetic concentrations dragged by vortex motion of solar photospheric plasma Authors: Balmaceda, L.; Vargas Domínguez, S.; Palacios, J.; Cabello, I.; Domingo, V. Bibcode: 2010A&A...513L...6B Altcode: 2010arXiv1004.1185B Vortex-type motions have been measured by tracking bright points in high-resolution observations of the solar photosphere. These small-scale motions are thought to be determinant in the evolution of magnetic footpoints and their interaction with plasma and therefore likely to play a role in heating the upper solar atmosphere by twisting magnetic flux tubes. We report the observation of magnetic concentrations being dragged towards the center of a convective vortex motion in the solar photosphere from high-resolution ground-based and space-borne data. We describe this event by analyzing a series of images at different solar atmospheric layers. By computing horizontal proper motions, we detect a vortex whose center appears to be the draining point for the magnetic concentrations detected in magnetograms and well-correlated with the locations of bright points seen in G-band and CN images. Title: Observations of Magnetic Elements in the Quiet Sun Internetwork Authors: Balmaceda, L. A.; Palacios, J.; Cabello, I.; Domingo, V. Bibcode: 2009ASPC..415..156B Altcode: We present here the analysis of high-resolution images of the quiet Sun at disk center taken with the Solar Optical Telescope (SOT) on board Hinode in the CN bandhead (388.35 nm) and magnetograms in the Mg I line (517.27 nm). These observations are complemented with data from the Swedish 1m Solar Telescope (SST). All data sets were obtained during the Hinode/Canary Islands joint campaign (HOP 0014) in September, 2007. In particular, we investigate the morphology, radiative and magnetic properties of small-scale elements in the solar atmosphere. Title: Solar Surface Magnetism and Irradiance on Time Scales from Days to the 11-Year Cycle Authors: Domingo, V.; Ermolli, I.; Fox, P.; Fröhlich, C.; Haberreiter, M.; Krivova, N.; Kopp, G.; Schmutz, W.; Solanki, S. K.; Spruit, H. C.; Unruh, Y.; Vögler, A. Bibcode: 2009SSRv..145..337D Altcode: The uninterrupted measurement of the total solar irradiance during the last three solar cycles and an increasing amount of solar spectral irradiance measurements as well as solar imaging observations (magnetograms and photometric data) have stimulated the development of models attributing irradiance variations to solar surface magnetism. Here we review the current status of solar irradiance measurements and modelling efforts based on solar photospheric magnetic fields. Thereby we restrict ourselves to the study of solar variations from days to the solar cycle. Phenomenological models of the solar atmosphere in combination with imaging observations of solar electromagnetic radiation and measurements of the photospheric magnetic field have reached high enough quality to show that a large fraction (at least, about 80%) of the solar irradiance variability can be explained by the radiative effects of the magnetic activity present in the photosphere. Also, significant progress has been made with magnetohydrodynamic simulations of convection that allow us to relate the radiance of the photospheric magnetic structures to the observations. Title: Convectively Driven Vortex Flows in the Sun Authors: Bonet, J. A.; Márquez, I.; Sánchez Almeida, J.; Cabello, I.; Domingo, V. Bibcode: 2008ApJ...687L.131B Altcode: 2008arXiv0809.3885B We have discovered small whirlpools in the Sun, with a size similar to terrestrial hurricanes (lesssim0.5 Mm). The theory of solar convection predicts them, but they had remained elusive so far. The vortex flows are created at the downdrafts where the plasma returns to the solar interior after cooling down, and we detect them because some magnetic bright points (BPs) follow a logarithmic spiral on their way to being engulfed by a downdraft. Our disk-center observations show 0.9 × 10-2 vortexes per Mm2, with a lifetime of the order of 5 minutes, and with no preferred sense of rotation. They are not evenly spread out over the surface, but they seem to trace the supergranulation and the mesogranulation. These observed properties are strongly biased by our type of measurement, unable to detect vortexes except when they are engulfing magnetic BPs. Title: Convectively driven vortex flows in the Sun Authors: Bonet, J. A.; Márquez, I.; Sánchez Almeida, J.; Cabello, I.; Domingo, V. Bibcode: 2008iac..talk..143B Altcode: 2008iac..talk...26B No abstract at ADS Title: Small magnetic structures in the photosphere, radiative properties Authors: Palacios, Judith; Domingo, Vicente; Cabello, Iballa; Bonet, José Antonio; Sánchez Almeida, Jorge Bibcode: 2008cosp...37.2331P Altcode: 2008cosp.meet.2331P The three dimensional structure of small magnetic field features in the photosphere, their dynamic behavior and their radiative properties are studied. We analyze data obtained in simultaneous observations made on Sept 29 and 30, 2007 with the HINODE spacecraft and the Swedish Solar Telescope (SST) in La Palma in different wavelengths, such as CaII (396.85 nm) and CN (388.35 nm) and other with Hinode data; and Gband (430.56 nm) with SST. Tha analysis is completed with high resolution Gband and Gcontinuum (436.39 nm) images from SST obtained on 2005 and 2006. Magnetograms have been obtained from both observatories. SST images have been processed with MOMFB code. Ribbon-like structures and "flowers" are studied in detail. Comparisons with solar atmospheric models are presented. Title: The DynaMICS perspective Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies, S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.; Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat, E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.; Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes, I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.; Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.; Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.; Thompson, M.; Vauclair, S.; Zahn, J. P. Bibcode: 2006ESASP.624E..24T Altcode: 2006soho...18E..24T No abstract at ADS Title: Scientific Objectives of the Novel Formation Flying Mission Aspiics Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies, S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.; Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat, E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.; Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes, I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.; Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.; Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.; Thompson, M.; Vauclair, S.; Zahn, J. P. Bibcode: 2006ESASP.617E.164L Altcode: 2006soho...17E.164L No abstract at ADS Title: The EUV Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO): Science Plan and Instrument Overview Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies, S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.; Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat, E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.; Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes, I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.; Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.; Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.; Thompson, M.; Vauclair, S.; Zahn, J. P. Bibcode: 2006ESASP.617E.165W Altcode: 2006soho...17E.165W No abstract at ADS Title: The Dynamics Project Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies, S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.; Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat, E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.; Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes, I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.; Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.; Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.; Thompson, M.; Vauclair, S.; Zahn, J. P. Bibcode: 2006ESASP.617E.162T Altcode: 2006soho...17E.162T No abstract at ADS Title: Solar Photospheric Magnetic Elements Dimension and Radiance Authors: Cabello, I.; Domingo, V. Bibcode: 2006ESASP.617E..55C Altcode: 2006soho...17E..55C No abstract at ADS Title: Detailed design of the imaging magnetograph experiment (IMaX): a visible imager magnetograph for the Sunrise mission Authors: Álvarez-Herrero, A.; Belenguer, T.; Pastor, C.; González, L.; Heredero, R. L.; Ramos, G.; Reina, M.; Sánchez, A.; Villanueva, J.; Sabau, L.; Martínez Pillet, V.; Bonet, J. A.; Collados, M.; Jochum, L.; Ballesteros, E.; Medina Trujillo, J. L.; Ruiz, Cobo B.; González, J. C.; del Toro Iniesta, J. C.; López Jiménez, A. C.; Castillo Lorenzo, J.; Herranz, M.; Jerónimo, J. M.; Mellado, P.; Morales, R.; Rodríguez, J.; Domingo, V.; Gasent, J. L.; Rodríquez, P. Bibcode: 2006SPIE.6265E..4CA Altcode: 2006SPIE.6265E.132A In this work, it is described the Imaging Magnetograph eXperiment, IMaX, one of the three postfocal instruments of the Sunrise mission. The Sunrise project consists on a stratospheric balloon with a 1 m aperture telescope, which will fly from the Antarctica within the NASA Long Duration Balloon Program. IMaX will provide vector magnetograms of the solar surface with a spatial resolution of 70 m. This data is relevant for understanding how the magnetic fields emerge in the solar surface, how they couple the photospheric base with the million degrees of temperature of the solar corona and which are the processes that are responsible of the generation of such an immense temperatures. To meet this goal IMaX should work as a high sensitivity polarimeter, high resolution spectrometer and a near diffraction limited imager. Liquid Crystal Variable Retarders will be used as polarization modulators taking advantage of the optical retardation induced by application of low electric fields and avoiding mechanical mechanisms. Therefore, the interest of these devices for aerospace applications is envisaged. The spectral resolution required will be achieved by using a LiNbO 3 Fabry-Perot etalon in double pass configuration as spectral filter before the two CCDs detectors. As well phase-diversity techniques will be implemented in order to improve the image quality. Nowadays, IMaX project is in the detailed design phase before fabrication, integration, assembly and verification. This paper briefly describes the current status of the instrument and the technical solutions developed to fulfil the scientific requirements. Title: The intensity contrast of solar photospheric faculae and network elements. II. Evolution over the rising phase of solar cycle 23 Authors: Ortiz, A.; Domingo, V.; Sanahuja, B. Bibcode: 2006A&A...452..311O Altcode: 2006astro.ph..2556O We studied the radiative properties of small magnetic elements (active region faculae and the network) during the rising phase of solar cycle 23 from 1996 to 2001, determining their contrasts as a function of heliocentric angle, magnetogram signal, and the solar cycle phase. We combined near-simultaneous full disk images of the line-of-sight magnetic field and photospheric continuum intensity provided by the MDI instrument on board the SOHO spacecraft. Sorting the magnetogram signal into different ranges allowed us to distinguish between the contrast of different magnetic structures. We find that the contrast center-to-limb variation (CLV) of these small magnetic elements is independent of time with a 10% precision, when measured during the rising phase of solar cycle 23. A 2-dimensional empirical expression for the contrast of photospheric features as a function of both the position on the disk and the averaged magnetic field strength was determined, showing its validity through the studied time period. A study of the relationship between magnetogram signal and the peak contrasts shows that the intrinsic contrast (maximum contrast per unit of magnetic flux) of network flux tubes is higher than that of active region faculae during the solar cycle. Title: Centre-to-limb variation of photospheric facular radiance and image resolution Authors: Domingo, Vicente; Ortiz, Ada; Sanahuja, Blai; Cabello, Iballa Bibcode: 2005AdSpR..35..345D Altcode: We study the effect of the angular resolution on the determination of the angular properties of the facular radiance. We analyze photospheric intensity in the continuum, around the Ni 676.8 nm line, and longitudinal magnetic field along the line of sight, measured by the MDI instrument aboard SOHO with two spatial resolutions, 4″ and 1.2″ (2″ and 0.6″ pixels, respectively). The effect of the limited photometric sensitivity of the instrument and the limited information on the angular structure of the magnetic field tubes are considered. Our study of the high-resolution data shows that intensity contrast of magnetic features between 80 and 600 Gauss increases from centre to limb up to a maximum that occurs at higher heliocentric angles ( θ) when obtained with higher resolution data than for lower resolution data. There is a suggestion that at heliocentric angles below about 75° there is only a monotonic increase in the contrast as one goes from cos ( θ) = 1 to cos ( θ) = 0.2. Title: The imaging magnetograph eXperiment for the SUNRISE balloon Antarctica project Authors: Martinez Pillet, Valentin; Bonet, Jose A.; Collados, Manuel V.; Jochum, Lieselotte; Mathew, S.; Medina Trujillo, J. L.; Ruiz Cobo, B.; del Toro Iniesta, Jose Carlos; Lopez Jimenez, A. C.; Castillo Lorenzo, J.; Herranz, M.; Jeronimo, J. M.; Mellado, P.; Morales, R.; Rodriguez, J.; Alvarez-Herrero, Alberto; Belenguer, Tomas; Heredero, R. L.; Menendez, M.; Ramos, G.; Reina, Manuel; Pastor, C.; Sanchez, A.; Villanueva, J.; Domingo, Vicente; Gasent, J. L.; Rodriguez, P. Bibcode: 2004SPIE.5487.1152M Altcode: The SUNRISE balloon project is a high-resolution mission to study solar magnetic fields able to resolve the critical scale of 100 km in the solar photosphere, or about one photon mean free path. The Imaging Magnetograph eXperiment (IMaX) is one of the three instruments that will fly in the balloon and will receive light from the 1m aperture telescope of the mission. IMaX should take advantage of the 15 days of uninterrupted solar observations and the exceptional resolution to help clarifying our understanding of the small-scale magnetic concentrations that pervade the solar surface. For this, IMaX should act as a diffraction limited imager able to carry out spectroscopic analysis with resolutions in the 50.000-100.000 range and capable to perform polarization measurements. The solutions adopted by the project to achieve all these three demanding goals are explained in this article. They include the use of Liquid Crystal Variable Retarders for the polarization modulation, one LiNbO3 etalon in double pass and two modern CCD detectors that allow for the application of phase diversity techniques by slightly changing the focus of one of the CCDs. Title: Excess facular emission from an isolated active region during solar minimum: the example of NOAA AR 7978 Authors: Ortiz, A.; Domingo, V.; Sanahuja, B.; Fröhlich, C. Bibcode: 2004JASTP..66...67O Altcode: 2004JATP...66...67O The facular contribution to solar irradiance variations on the short time scale is studied by analyzing a simple case of an isolated active region that crossed the solar disk during the 1996 minimum of activity, NOAA AR 7978. Its passage during several Carrington rotations, specifically from rotation 1911 to 1916, allows us to analyze the evolution of the angular distribution of the excess radiance of the facular region using SOHO/VIRGO and MDI data. We associate this evolution with the evolution of the extent corresponding to the isolated active region as well as with the aging of the region itself. Finally, we evaluate the total (i.e. in all directions) emission of this facular region and its spectral and temporal evolution. Title: Magnetic field tubes emerging in the photosphere Authors: Domingo, V.; Marco, E.; Ortiz, A.; Sanahuja, B. Bibcode: 2004cosp...35.4732D Altcode: 2004cosp.meet.4732D Magnetic field tubes emerging in the photosphere are the dominant contributors to the solar irradiance variations with time. The knowledge of the radiative properties of the photospheric magnetic field elements is, therefore, of high interest to understand the solar irradiance. A classical way to quantify the angular distribution of their radiative properties is the measurement of the contrast between their radiance and the one from the surrounding photosphere as a function of their heliocentric angle location, known as centre-to-limb-variation (CLV). There are many published measurements of the CLV of photospheric small magnetic elements, mostly faculae, made in different conditions and giving different results. One of the parameters that may be different from one observation to another is the angular resolution. We study the effect of the angular resolution on the determination of the angular properties of the facular radiance, with measurements of photospheric intensity in the continuum, around the Fe 676.8 nm, and of the longitudinal magnetic field, along the line of sight, made with the MDI instrument aboard SOHO with two resolutions, 4 arc seconds and 1.2 arc seconds (2 and 0.6 arc second pixels, respectively) . The effect of the limited photometric sensitivity of the instrument and the limited information on the angular structure of the magnetic field tubes are considered. Title: Contribution of the small photospheric magnetic elements to the long-term solar irradiance Authors: Ortiz, Ada; Domingo, Vicente; Sanahuja, Blai Bibcode: 2003ESASP.535...43O Altcode: 2003iscs.symp...43O We used near-simultaneous full disk magnetograms and images of the photospheric continuum intensity provided by MDI/SOHO to analyze the long-term evolution of the intensity contrast of small magnetic features - faculae and magnetic network - as a function of position, magnetic signal and time, from minimum to maximum of cycle 23. We find that the spectral irradiance characteristics, at 676.8 nm, of the small photospheric magnetic elements are practically invariable throughout the rising phase of solar cycle 23. A preliminary statistical analysis of the magnetic field suggests that the small magnetic elements are likely to provide a significant contribution to the solar cycle irradiance change. Title: IMax: a visible magnetograph for SUNRISE Authors: Jochum, Lieselotte; Collados, Manuel; Martínez Pillet, Valentin; Bonet, Jose A.; del Toro Iniesta, Jose Carlos; Lopez, Antonio; Alvarez-Herrero, Alberto; Reina, Manuel; Fabregat, Juan; Domingo, Vicente Bibcode: 2003SPIE.4843...20J Altcode: The description of the Imaging Magnetograph eXperiment (IMaX) is presented in this contribution. This is a magnetograph which will fly by the end of 2006 on a stratospheric balloon, together with other instruments (to be described elsewhere). Especial emphasis is put on the scientific requirements to obtain diffraction-limited visible magnetograms, on the optical design and several constraining characteristics, such as the wavelength tuning or the crosstalk between the Stokes parameters. Title: SOHO, Yohkoh, Ulysses and Trace: The four solar missions in perspective, and available resources Authors: Domingo, V. Bibcode: 2002Ap&SS.282..171D Altcode: Four solar observing spacecraft, now in operation, have obtained and continue to obtain data during the late phase of solar cycle 22 and hopefully most of cycle 23. The data are available for scientific analysis, practically in an unrestricted manner. A large pool of software suited for the processing and to help programming any data analysis is freely available. An almost random list of results that are being obtained with this data is presented as an example of what can be done by analysing the data from these spacecraft, either alone or combining results among them, with ground observatories, or with other spacecraft, such as those that measure particles and fields in interplanetary space or in geospace, to study solar physics or solar-terrestrial relations. Title: On the intensity contrast of solar photospheric faculae and network elements Authors: Ortiz, A.; Solanki, S. K.; Domingo, V.; Fligge, M.; Sanahuja, B. Bibcode: 2002A&A...388.1036O Altcode: 2002astro.ph..7008O Sunspots, faculae and the magnetic network contribute to solar irradiance variations. The contribution due to faculae and the network is of basic importance, but suffers from considerable uncertainty. We determine the contrasts of active region faculae and the network, both as a function of heliocentric angle and magnetogram signal. To achieve this, we analyze near-simultaneous full disk images of photospheric continuum intensity and line-of-sight magnetic field provided by the Michelson Doppler Interferometer (MDI) on board the SOHO spacecraft. Starting from the surface distribution of the solar magnetic field we first construct a mask, which is then used to determine the brightness of magnetic features, and the relatively field-free part of the photosphere separately. By sorting the magnetogram signal into different bins we are able to distinguish between the contrasts of different concentrations of magnetic field. We find that the center-to-limb variation (CLV) of the contrast changes strongly with magnetogram signal. Thus, the contrasts of active region faculae (large magnetogram signal) and the network (small signal) exhibit a very different CLV, showing that the populations of magnetic flux tubes that underly the two kinds of features are different. The results are compatible with, on average, larger flux tubes in faculae than in the network. This implies that these elements need to be treated separately when reconstructing variations of the total solar irradiance with high precision. We have obtained an analytical expression for the contrast of photospheric magnetic features as a function of both position on the disk and spatially averaged magnetic field strength, by performing a 2-dimensional fit to the observations. We also provide a linear relationship between magnetogram signal and the mu =cos (theta ), where theta is the heliocentric angle, at which the contrast is maximal. Finally, we show that the maximum contrast per unit magnetic flux decreases rapidly with increasing magnetogram signal, supporting earlier evidence that the intrinsic contrast of magnetic flux tubes in the network is higher. Title: Variation of the facular and network contrast during the rising phase of cycle 23 Authors: Ortiz, A.; Domingo, V.; Sanahuja, B.; Solanki, S. K. Bibcode: 2002ESASP.508..185O Altcode: 2002soho...11..185O Magnetic activity contributes to solar irradiance variations, both on short and long time-scales. While sunspots and active region faculae are the dominant contributors to irradiance changes on time-scales of days to weeks, the origin of the long-term increase of the irradiance between activity minimum and maximum (~0.1%) is still debated. It has been proposed that the small-scale magnetic elements composing the enhanced and quiet network contribute substantially to this increase. To contribute to this debate, we attempt to see if there is a change in the radiative properties of these elements along the solar cycle, and to evaluate such a change. We use near-simultaneous full disk magnetograms and images of the photospheric continuum intensity provided by MDI/SOHO. We have studied the center-to-limb variations (CLV) of the contrast as a function of magnetic strength and we are now analyzing how the noise level of the images changes throughout time, as a preliminary step towards an analysis of the temporal irradiance variations. Title: A first step towards proton flux forecasting Authors: Aran, A.; Sanahuja, B.; Lario, D.; Domingo, V. Bibcode: 2002cosp...34E1078A Altcode: 2002cosp.meetE1078A We present a preliminary version of a potential tool for real time proton flux prediction which provides proton flux profiles and cumulative fluence profiles at 0.5 MeV and 2 MeV of Solar Energetic Particle (SEP) events, from their onset up to the arrival of the interplanetary shock at the spacecraft position (located at 1 AU or 0.4 AU). Based on the proton transport model by Lario et al. (1998) and the MHD shock propagation model of Wu et al. (1983), we have generated a database containing "synthetic" profiles of the proton fluxes and cumulative fluences of 384 SEP events. These events describe different interplanetary scenarios which comprise a set of various MHD-shocks and several heliolongitude locations of the solar activity sites, as well as different conditions for particle transport. We are currently validating the applicability of this code for space weather forecasting by comparing the resulting "synthetic" flux profiles with those of several real SEP events. References: Lario D., Sanahuja B. and Heras A.M., 1998, Astrophys. J., 509, 415 Wu S.T., Dryer M., Han S.M., 1983, Solar Physics, 84, 395 Title: Four years of SOHO discoveries - some highlights. Authors: Fleck, B.; Brekke, P.; Haugan, S.; Duarte, L. S.; Domingo, V.; Gurman, J. B.; Poland, A. I. Bibcode: 2000ESABu.102...68F Altcode: Analysis of the helioseismic data from SOHO has shed new light on solar and heliosheric physics: the structure and dynamics of the solar interior, the heating and dynamics of the solar corona, and the acceleration and composition of the solar wind. Title: An Example of Isolated Active Region Energy Evolution: NOAA AR 7978 Authors: Ortiz, A.; Domingo, V.; Sanahuja, B.; Sánchez, L. Bibcode: 2000ESASP.463..395O Altcode: 2000sctc.proc..395O The facular contribution to solar irradiance variations on the short time scale is studied by analysing a simple case of an isolated active region, NOAA AR7978, during the minimum of 1996. We focus on the relationship between the temporal evolution of the active region surface magnetic field, its physical characteristics and the total facular energy emission, using VIRGO/SOHO and MDI/SOHO data sets. Title: On the Contrast of Faculae and Small Magnetic Features Authors: Ortiz, A.; Solanki, S. K.; Fligge, M.; Domingo, V.; Sanahuja, B. Bibcode: 2000ESASP.463..399O Altcode: 2000sctc.proc..399O Sunspots, faculae and the magnetic network contribute to solar irradiance variations. The contribution due to faculae and the network is important for understanding solar irradiance variations, but suffers from considerable uncertainty. We focus our study on the faculae and the network which produce an increase in the irradiance. Data from the Michelson Doppler Interferometer (MDI) are employed. Starting from the surface distribution of the solar magnetic field we build a mask to detect bright features and study their contrast dependence on limb angle and magnetic field. By sorting the magnetic field strength into different bins we can distinguish between different associated bright features. We find that the contrast of active region faculae and the network exhibits different centre to limb variations, implying that they need to be treated separately when reconstructing variations of the total solar irradiance. Title: Division XI: Space and High Energy Astrophysics(Astrophysique Spatiale et Des Hautes Energies) Authors: Wamsteker, Willem; Baliunas, S.; Brosch, N.; Cesarsky, C.; Courvoisier, Th. -J. L.; da Costa, J. M.; Domingo, V.; Fransson, C.; Fabian, A.; Fazio, G.; Hasinger, G.; Inoe, H.; Li, Zhongyuan; O'Brien, P.; Oertel, G.; Okuda, H.; Quintana, H.; Rangarajan, T. N.; Schilizzi, R.; Shustov, B.; Thronson, H.; Vilhu, O.; Wang, Zhenru Bibcode: 2000IAUTA..24..357W Altcode: No abstract at ADS Title: Observations of the latitudinal variation of the solar radiance of non-active regions of the sun. Authors: Domingo, V.; Sanchez, L.; Appourchaux, T.; Andersen, B. Bibcode: 1998IAUS..185..111D Altcode: The Luminosity Oscillations Imager (LOI) of the VIRGO experiment aboard SOHO provides continuous measurement of the solar irradiance in a 5 nm band around 500 nm. The solar image is broken down in 12 pixels distributed in 4 latitudinal bands. The first year of operation of the instrument has taken place during a period of solar minimum activity. The measurements provide an indication of the distribution of the solar irradiance variations versus latitude. Contributions to the observed variations due to the presence of active regions are discussed in relation to the possible effect of the evolving solar cycle (structure of the convection zone): short term variations versus long term variations. The problem of the photometric stability of the measurements needed for the investigation is thoroughly treated by self consistency and by comparison with other instruments on SOHO (VIRGO sun- photometers and MDI intensity measurements). Title: Overview of the SOHO Mission Authors: Domingo, Vicente Bibcode: 1998sers.conf..375D Altcode: No abstract at ADS Title: On the Effect of Active Regions on the Solar Irradiance Authors: Domingo, V.; Sanchez, L.; Appourchaux, T.; Fröhlich, C.; Wehrli, C.; Crommelynck, D.; Pap, J. Bibcode: 1997ESASP.415..469D Altcode: 1997cpsh.conf..469D No abstract at ADS Title: SOHO, its day in the Sun Authors: Domingo, V. Bibcode: 1997AdSpR..20..581D Altcode: SOHO, the Solar and Heliospheric Observatory, is a project of international cooperation between ESA and NASA to study the Sun, from its deep core to the outer corona, and the solar wind. Three helioseismology instruments are providing unique data for the study of the structure and dynamics of the solar interior, from the very deep core to the outermost layers of the convection zone. A set of five complementary remote sensing instruments, consisting of EUV, UV and visible light imagers, spectrographs and coronagraphs, give us our first comprehensive view of the outer solar atmosphere and corona, leading to a better understanding of the enigmatic coronal heating and solar wind acceleration processes. Finally, three experiments complement the remote sensing observations by making in-situ measurements of the composition and energy of the solar wind and charged energetic particles, and another instrument maps the neutral hydrogen in the heliosphere, and its dynamic change of the Solar Wind. This paper highlights some of the first results from SOHO. Title: Study of the Effect of Active Regions on the Solar Irradiance During Solar Minimum Authors: Domingo, V.; Sanchez, L.; Appourchaux, T.; Froehlich, C.; Wehrli, C.; Hoeksema, T.; Pap, J. Bibcode: 1997SPD....28.0206D Altcode: 1997BAAS...29..893D We have determined both the size of the area that contributes to the solar irradiance increase around an active region and the angular distribution of the radiance excess in it, using data obtained during about one year around solar minimum (April 1996 - April 1997). During the solar minimum and the early raising phase of the new maximum it is possible to study the effect of isolated active regions while there are few of them. The result of this study will be important to separate the contribution of the active regions to the solar irradiance change during the solar cycle from any underlying long term effect, if there is one. The solar radiance measured by the Low-resolution Oscillations Imager (LOI) of the VIRGO instrument and by the MDI instrument aboard SOHO is used to determine the dimension of the radiating area. The increase in irradance is determined by the Sun Photometers (SPM) and Radiometers on the VIRGO instrument. Title: First results from VIRGO on SoHO Authors: Frohlich, C.; Andersen, B. N.; Appourchaux, T.; Berthomieu, G.; Crommelynck, D. A.; Domingo, V.; Fichot, A.; Finsterle, W.; Gómez, M. F.; Gough, D.; Jiménez, A.; Leifsen, T.; Lombaerts, M.; Pap, J. M.; Provost, J.; Roca Cortés, T.; Romero, J.; Roth, H. -J.; Sekii, T.; Telljohann, U.; Toutain, T.; Wehrli, C. Bibcode: 1997IAUS..181...67F Altcode: No abstract at ADS Title: The Solar and Heliospheric Observatory (SOHO) in 1996. Authors: Domingo, V.; Fleck, B.; Martens, P.; Sanchez, L. Bibcode: 1997joso.proc....4D Altcode: This report gives a brief overview of SOHO's scientific production in its first year of operation. Title: First Results from VIRGO, the Experiment for Helioseismology and Solar Irradiance Monitoring on SOHO Authors: Fröhlich, Claus; Andersen, Bo N.; Appourchaux, Thierry; Berthomieu, Gabrielle; Crommelynck, Dominique A.; Domingo, Vicente; Fichot, Alain; Finsterle, Wolfgang; Gómez, Maria F.; Gough, Douglas; Jiménez, Antonio; Leifsen, Torben; Lombaerts, Marc; Pap, Judit M.; Provost, Janine; Roca Cortés, Teodoro; Romero, José; Roth, Hansjörg; Sekii, Takashi; Telljohann, Udo; Toutain, Thierry; Wehrli, Christoph Bibcode: 1997SoPh..170....1F Altcode: First results from the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) on the ESA/NASA Mission SOHO (Solar and Heliospheric Observatory) are reported. The observations started mid-January 1996 for the radiometers and sunphotometers and near the end of March for the luminosity oscillation imager. The performance of all the instruments is very good, and the time series of the first 4-6 months are evaluated in terms of solar irradiance variability, solar background noise characteristics and p-mode oscillations. The solar irradiance is modulated by the passage of active regions across the disk, but not all of the modulation is straightforwardly explained in terms of sunspot flux blocking and facular enhancement. Helioseismic inversions of the observed p-mode frequencies are more-or-less in agreement with the latest standard solar models. The comparison of VIRGO results with earlier ones shows evidence that magnetic activity plays a significant role in the dynamics of the oscillations beyond its modulation of the resonant frequencies. Moreover, by comparing the amplitudes of different components ofp -mode multiplets, each of which are influenced differently by spatial inhomogeneity, we have found that activity enhances excitation. Title: The first results from SOHO. Authors: Domingo, V.; Fleck, B.; Poland, A. Bibcode: 1996ESABu..87....7D Altcode: SOHO, launched by an Atlas II-AS from Cape Canaveral on 2 December 1995, was inserted into its halo orbit around the L1 Lagrangian point. Typical examples of the unique results being obtained with SOHO's instruments are presented. Title: SOLCON Solar Constant Observations from the ATLAS Missions Authors: Crommelynck, Dominique; Fichot, Alain; Domingo, Vicente; Lee, Robert, III Bibcode: 1996GeoRL..23.2293C Altcode: The solar constant observations obtained by the SOLCON/ATLAS experiment during the three successive missions are presented based on the Space Absolute Radiometric Reference (SARR) defined during the ATLAS-2 mission. The objectives of SOLCON, namely to obtain accurate measurements of the solar constant and to compare them with the observations obtained from free flyers in the hope of establishing a baseline and strategy for monitoring the solar constant at climate scale, have been achieved successfully with the three ATLAS missions. The long range objective of insuring the solar constant data continuity will, however, require that an alternative approach than that of the ATLAS program be found to fly and retrieve SOLCON. Title: The history of thge SOHO mission. Authors: Huber, M. C. E.; Bonnet, R. M.; Dale, D. C.; Arduini, M.; Fröhlich, C.; Domingo, V.; Whitcomb, G. Bibcode: 1996ESABu..86...25H Altcode: No abstract at ADS Title: ESA Report to the : 31 : COSPAR meeting held in Birmingham, UK July 1996 Authors: Benvenuti, P.; Chicarro, A.; Domingo, V. Bibcode: 1996ertc.book.....B Altcode: No abstract at ADS Title: VIRGO: Experiment for Helioseismology and Solar Irradiance Monitoring Authors: Fröhlich, Claus; Romero, José; Roth, Hansjörg; Wehrli, Christoph; Andersen, Bo N.; Appourchaux, Thierry; Domingo, Vicente; Telljohann, Udo; Berthomieu, Gabrielle; Delache, Philippe; Provost, Janine; Toutain, Thierry; Crommelynck, Dominique A.; Chevalier, André; Fichot, Alain; Däppen, Werner; Gough, Douglas; Hoeksema, Todd; Jiménez, Antonio; Gómez, Maria F.; Herreros, José M.; Cortés, Teodoro Roca; Jones, Andrew R.; Pap, Judit M.; Willson, Richard C. Bibcode: 1995SoPh..162..101F Altcode: The scientific objective of the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) is to determine the characteristics of pressure and internal gravity oscillations by observing irradiance and radiance variations, to measure the solar total and spectral irradiance and to quantify their variability over periods of days to the duration of the mission. With these data helioseismological methods can be used to probe the solar interior. Certain characteristics of convection and its interaction with magnetic fields, related to, for example, activity, will be studied from the results of the irradiance monitoring and from the comparison of amplitudes and phases of the oscillations as manifest in brightness from VIRGO, in velocity from GOLF, and in both velocity and continuum intensity from SOI/MDI. The VIRGO experiment contains two different active-cavity radiometers for monitoring the solar `constant', two three-channel sunphotometers (SPM) for the measurement of the spectral irradiance at 402, 500 and 862 nm, and a low-resolution imager (LOI) with 12 pixels, for the measurement of the radiance distribution over the solar disk at 500 um. In this paper the scientific objectives of VIRGO are presented, the instruments and the data acquisition and control system are described in detail, and their measured performance is given. Title: Preface Authors: Fleck, B.; Domingo, V.; Poland, A. Bibcode: 1995SoPh..162D...9F Altcode: No abstract at ADS Title: The SOHO mission. Authors: Fleck, B.; Domingo, V.; Poland, A. I. Bibcode: 1995SoPh..162.....F Altcode: SOHO, the Solar and Heliospheric Observatory, is a project of international cooperation between ESA and NASA to study the Sun, from its deep core to the outer corona. This special issue is dedicated to the SOHO payload and to its operation. Title: The SOHO Mission: an Overview Authors: Domingo, V.; Fleck, B.; Poland, A. I. Bibcode: 1995SoPh..162....1D Altcode: The Solar and Heliospheric Observatory (SOHO) is a space mission that forms part of the Solar-Terrestrial Science Program (STSP), developed in a collaborative effort by the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA). The STSP constitutes the first "cornerstone" of ESA's long-term programme known as "Space Science — Horizon 2000". The principal scientific objectives of the SOHO mission are a) to reach a better understanding of the structure and dynamics of the solar interior using techniques of helioseismology, and b) to gain better insight into the physical processes that form and heat the Sun's corona, maintain it and give rise to its acceleration into the solar wind. To achieve these goals, SOHO carries a payload consisting of 12 sets of complementary instruments. SOHO is a three-axis stabilized spacecraft with a total mass of 1850 kg; 1150 W of power will be provided by the solar panels. The payload weighs about 640 kg and will consume 450 W in orbit. SOHO will be launched by an ATLAS II-AS and will be placed in a halo orbit around the Sun-Earth L1 Lagrangian point where it will be continuously pointing to Sun centre with an accuracy of 10 arcsec. Pointing stability will be better than 1 arcsec over 15 min intervals. The SOHO payload produces a continuous science data stream of 40 kbits/s which will be increased by 160 kbits/s whenever the solar oscillations imaging instrument is operated in its highrate mode. Telemetry will be received by NASA's Deep Space Network (DSN). Planning, coordination and operation of the spacecraft and the scientific payload will be conducted from the Experiment Operations Facility (EOF) at NASA's Goddard Space Flight Center (GSFC). Title: The SOHO payload and its testing. Authors: Berner, C.; Domingo, V. Bibcode: 1995ESABu..84...92B Altcode: The following topics are dealt with: history, science objectives and payload, the AIV programme. Title: Helioseismology Authors: Hoeksema, J. T.; Domingo, V.; Fleck, B.; Battrick, Bruce Bibcode: 1995ESASP.376b....H Altcode: 1995help.confP....H No abstract at ADS Title: SOHO: The Solar and Heliospheric Observatory Authors: Domingo, V.; Fleck, B.; Poland, A. I. Bibcode: 1995SSRv...72...81D Altcode: The Solar and Heliospheric Observatory (SOHO), together with the Cluster mission, constitutes ESA's Solar Terrestrial Science Programme (STSP), the first “Cornerstone” of the Agency's long-term programme “Space Science — Horizon 2000”. STSP, which is being developed in a strong collaborative effort with NASA, will allow comprehensive studies to be made of the both the Sun's interior and its outer atmosphere, the acceleration and propagation of the solar wind and its interaction with the Earth. This paper gives a brief overview of one part of STSP, the SOHO mission. Title: The SOHO Mission and Helioseismology Authors: Domingo, V. Bibcode: 1995ESASP.376a...3D Altcode: 1995soho....1....3D; 1995heli.conf....3D Three of the SOHO scientific instruments are devoted to helioseismology, and the mission has been designed with specifications that are required to obtain good oscillations measurements. The three instruments were selected to complement each other to achieve a comprehensive set of data to tackle the pending helioseismologic problems that were considered difficult to solve with ground-based instruments. GOLF (l = 0-3) and VIRGO (l = 0-7) in the low degree modes area and MDI in the complete range up to l = 4000 modes. In addition, several instruments of SOHO investigate, by imaging and spectroscopy, the transition region and the corona. Three other investigations aboard SOHO study "in situ" the resulting solar wind and energetic particles. Title: VIRGO - the Solar Monitor Experiment on SOHO Authors: Appourchaux, T.; Domingo, V.; Frohlich, C.; Romero, J.; Wehrli, C.; Andersen, B. N.; Berthomieu, G.; Delache, P.; Crommelynck, D.; Jimenez, A.; Roca Cortes, T.; Jones, A. R. Bibcode: 1995ASPC...76..408A Altcode: 1995gong.conf..408A No abstract at ADS Title: The SOHO mission Authors: Fleck, B.; Domingo, V.; Poland, A. Bibcode: 1995somi.book.....F Altcode: No abstract at ADS Title: SOHO: The Solar and Heliospheric Observatory Authors: Domingo, V.; Fleck, B.; Poland, A. I. Bibcode: 1995hlh..conf...81D Altcode: No abstract at ADS Title: Helioseismology Authors: Hoeksema, J. T.; Domingo, V.; Fleck, B.; Battrick, Bruce Bibcode: 1995ESASP.376a....H Altcode: 1995heli.conf.....H No abstract at ADS Title: The SOHO mission Poland. Authors: Fleck, B.; Domingo, V.; Poland, Arthur I. Bibcode: 1995sohp.book.....F Altcode: 1995QB521.S5828.... No abstract at ADS Title: Book Review: Solar photo rates for planetary atmospheres and atmospheric pollutants / Kluwer, 1992 Authors: Domingo, V.; Domingo, V. Bibcode: 1994SoPh..154..401D Altcode: 1994SoPh..154..401H No abstract at ADS Title: The scientific payload of the space-based Solar and Heliospheric Observatory (SOHO) Authors: Domingo, V.; Fleck, B.; Poland, A. I. Bibcode: 1994SSRv...70....7D Altcode: The space-based Solar and Heliospheric Observatory (SOHO) is a joint venture of ESA and NASA within the frame of the Solar Terrestrial Science Programme (STSP), the first “Cornerstone” of ESA's long-term programme “Space Science — Horizon 2000”. The principal scientific objectives of the SOHO mission are: a) a better understanding of the structure and dynamics of the solar interior using techniques of helioseismology, and b) a better insight into the physical processes that form and heat the Sun's corona, maintain it and give rise to its acceleration into the solar wind. To achieve these goals, SOHO carries a payload consisting of 12 sets of complementary instruments which are briefly described here. Title: SOHO operations and ground system Authors: Poland, A. I.; Domingo, V.; Fleck, B. Bibcode: 1994SSRv...70...13P Altcode: SOHO is a joint ESA/NASA mission to study the sun from its interior to, and including, the solar wind in interplanetary space. It is currently scheduled for launch in 1995. After launch SOHO with be operated from the Experiment Operations Facility (EOF) at Goddard Space Flight Center (GSFC). The EOF will consist of facilities for instrument commanding, data reception, data reduction and data analysis. In this paper the operations concepts including instrument ground commanding from the EOF and communications capabilities between the EOF and ground observatories and the public networks in general will be described. Title: Preliminary results of solar constant observations with the SOLCON experiment on ATLAS-1 Authors: Crommelynck, D.; Domingo, V.; Barkstrom, B.; Lee, R. B.; Donaldson, J.; Telljohann, U.; Warren, L.; Fichot, A. Bibcode: 1994AdSpR..14i.253C Altcode: 1994AdSpR..14..253C A brief description is given of the SOLCON experiment on ATLAS 1, its scientific and technical objectives, as well as its measurement principle and its on board chronology of operations. A preliminary value of the solar constant during the third solar operation of the mission is also provided. Title: Summary of Future Space Observations at Different Wavelengths Authors: Domingo, V. Bibcode: 1994svsp.coll..101D Altcode: 1994IAUCo.143P.101D No abstract at ADS Title: Total Solar Irradiance Observations from the EURECA and ATLAS Experiments Authors: Crommelynck, D.; Domingo, V.; Fichot, A.; Lee, B. Bibcode: 1994svsp.coll...63C Altcode: 1994IAUCo.143P..63C No abstract at ADS Title: SOHO Science Opportunities Authors: Fleck, B.; Domingo, V.; Poland, A. I. Bibcode: 1994scs..conf..609F Altcode: 1994IAUCo.144..609F The principal scientific objectives of the SOHO mission are: a) a better understanding of the structure and dynamics of the solar interior using techniques of helioseismology, and b) a better insight into the physical processes that form and heat the Sun's corona, maintain it and give rise to its acceleration into the solar wind. To achieve these goals, SOHO carries a payload consisting of 12 sets of complementary instruments which are briefly described here. Title: SOHO Operations Authors: Fleck, B.; Domingo, V.; Poland, A. I. Bibcode: 1994scs..conf..614F Altcode: 1994IAUCo.144..614F SOHO, the Solar and Heliospheric Observatory, is currently scheduled for launch in 1995. After launch SOHO will be operated from the Experiment Operations Faciliy (EOF) at Goddard Space Flight Center (GSFC). The EOF will consist of facilities for instrument commanding, data reception, data reduction and data analysis. This paper briefly describes the operations concepts. Title: SOHO - The Solar and Heliospheric Observatory Authors: Fleck, B.; Domingo, V. Bibcode: 1994smf..conf..408F Altcode: No abstract at ADS Title: SOHO: science objectives and capabilities Authors: Fleck, B.; Domingo, V.; Poland, A. I. Bibcode: 1994ASIC..433..517F Altcode: No abstract at ADS Title: Invited Talk: (SOHO Operations and Coordination with Ground-based Observatories) Authors: Domingo, V.; Fleck, B. Bibcode: 1993BAAS...25.1195D Altcode: No abstract at ADS Title: Some European activities in support of the SOHO mission. Authors: Huber, Martin C. E.; Domingo, Vicente Bibcode: 1992ESASP.348..393H Altcode: 1992cscl.work..393H The rationale and potential functions of the European Science Data and Operations Centre (ESDOC) are outlined. Other efforts, namely the gathering of support - through the Joint Organisation for Solar Observations (JOSO) - for ground-based observations in the context of the SOHO mission, as well as the development of a vacuum-ultraviolet (VUV) transfer source standard - to be used for radiometrically intercomparing spectrometric SOHO instruments - are also described. Title: ESA's report to the 29th COSPAR Meeting Authors: Appourchaux, T.; Chicarro, A.; Domingo, V.; Fridlund, M.; Huber, M.; Innocenti, L.; Jakobsen, P.; Kessler, M.; Lebreton, J. P.; Parmar, A. Bibcode: 1992wadc.meet.....A Altcode: All ESA missions in operation, under development, or in planning are described. Missions beyond the operational phase are also presented if considerable effort is still being expended in supporting the data analysis through an archive. The aging and completed missions are: IUE, Exosat, Hipparcos, Giotto extended mission, Ulysses, and Hubble Space Telescope. The projects under development are: Infrared Space Observatory (ISO), the Solar Terrestrial Science Program (STSP) (which comprises the four Cluster spacecraft and the Solar and Heliospheric Observatory (SOHO)), the X-ray Multimirror Mission (XMM) and the Cassini/Huygens mission. Missions under study are: the Far Infrared Space Telescope (FIRST), the comet nucleus sample return (Rosetta), the International Gamma Ray Laboratory (INTEGRAL), a network of three semi hard landers to be placed on the Martian surface (MARSNET), a mission for probing the interior and rotation of stars (PRISMA), and a Satellite Test of the Equivalence Principle (STEP). Missions beyond Horizon 2000 are: Return to the Moon, interferometry from space, and Vulcan. ESA platforms described are Eureca (the European retrieval carrier) and Simuris (a solar system and stellar interferometric mission for ultrahigh resolution imaging and spectroscopy). Title: SOHO and Cluster. Solar and geospheric plasmas and solar structure. Authors: Domingo, V.; Schmidt, R. Bibcode: 1991EN.....22..213D Altcode: The SOHO/Cluster satellite missions will provide an unique opportunity to advance our understanding of the physics of the solar-terrestrial system. Title: Three Solar Filament Disappearances Associated with Interplanetary Low Energy Particle Events Authors: Sanahuja, B.; Heras, A. M.; Domingo, V.; Joselyn, J. A. Bibcode: 1991SoPh..134..379S Altcode: Three low-energy particle events (35-1600 keV) associated with interplanetary shocks, detected at 1 AU by ISEE-3, have been identified as originating in solar disappearing filaments instead of large flares. This increases to fourteen the number of events of this kind presently known. The observational characteristics of these non-flare generated events are similar to the ones of the other eleven events already known (i.e., absence of type II or IV bursts, weak X-ray emission, Hα brightening in the surroundings of the filament disappearance, frequent presence of a double-ribbon event, slow propagation of the generated interplanetary shock, lack of shock deceleration). Title: The SOHO Space Satellite: UV instrumentation. Authors: Poland, Arthur I.; Domingo, Vicente Bibcode: 1991SPIE.1343..310P Altcode: The solar and heliospheric observatory, SOHO will be placed into a halo orbit around the L1 sun-earth Lagrangian point in 1995. The authors describe the ultra-violet and EUV instruments designed to study the solar atmosphere from the chromosphere through the corona. The instruments and their basic characteristics are: 1) SUMER - a normal incidence telescope with a normal incidence spherical concave grating for stigmatic imaging to measure line profiles and images in the wavelength range from 500 Å to 1600 Å with a 1.5″resolution; 2) CDS - a grazing incidence telescope with one grazing incidence astigmatic spectrograph and one normal incidence toroidal grating spectrograph to measure line ratios and images in the range from 170 Å to 800 Å with a 2″resolution; 3) EIT - a normal incidence multilayered telescope to produce narrow band pass images in the spectral lines at 171 Å, 195 Å, 284 Å, and 304 Å with a 3″resolution; 4) UVCS - a normal incidence coronagraph with a normal incidence toroidal grating spectrograph to measure line profiles and images of several EUV lines from ≡500 Å to ≡1200 Å with a several arcsecond resolution; and 5) SWAN - a lens with hydrogen absorption cell and interference filter to measure Ly-α profiles in the far corona and heliosphere. Title: The helioseismology experiment on the Phobos planetary mission. Preliminary results Authors: Frohlich, C.; Bonnet, R. M.; Bruns, A. V.; Vial, J. C.; Delaboudiniere, J. P.; Domingo, V.; Kollath, Z.; Kotov, V. A.; Rachkovskii, D. N.; Wehrli, Ch.; Toulain, T.; Shumko, S. M. Bibcode: 1991BCrAO..83...18F Altcode: No abstract at ADS Title: The Solar Variations (SOVA) experiment in the EURECA space platform Authors: Crommelynck, D.; Domingo, V.; Fröhlich, C. Bibcode: 1991AdSpR..11d..83C Altcode: 1991AdSpR..11Q..83C The Solar Variations (SOVA) experiment aboard EURECA will measure the total and spectral irradiance of the Sun, and their variations. Aims of the experiment are: - to study the short term (hours to months) variations of the solar irradiance for the investigation of the mechanisms of energy redistribution in the convection zone, - to study periodic fluctuations, with periods between a few minutes and several hours, for helioseismology and, - to measure the absolute value of the solar constant to determine its long term variations when compared with previous and future measurements. Two absolute active cavity radiometers of different design will measure independently the value of the total solar irradiance, one relative radiometer will measure the variations of the total solar irradiance and five photometers will measure the variations of the spectral irradiance in 5-nm wide wavelength bands centred at 335, 480, 500, 546 and 865 nm. The European Retrievable Carrier (Eureca), is an ESA space platform that will be placed in orbit around the Earth by the NASA Shuttle in October 1991, and will be recovered after 6 months of operation. Title: Phase difference between irradiance and velocity in low degree solar p-modes Authors: Schrijver, C. J.; Jiménez, A.; Domingo, V.; Fröhlich, C. Bibcode: 1991AdSpR..11d..77S Altcode: 1991AdSpR..11Q..77S We derive phase differences between irradiance and full-disk velocity variations for l=0, 1, and 2 modes with order ranging from 11 up to 30 (1.8-4.3mHz). We use irradiance measurements from the IPHIR instrument flown on the PHOBOS mission to Mars during the second half of 1988, and simultaneous velocity measurements obtained at Tenerife. The IPHIR instrument measures broad-band irradiance fluctuations and the derived phase differences are therefore typical of the deep layers of the photosphere. We select three one week intervals from the 155 day observing interval of PHOBOS 2 for which simultaneous good quality velocity data are available. We find a smooth variation of the phase difference between irradiance at 500nm (5nm FWHM) and velocity from about 70° at 1.8mHz to 145° at 2.5mHz, while it remains roughly constant at 145° degrees up to at least 3.5mHz, and possibly up to 4.3mHz. We also show that the phase differences between the green (500nm) and red (865nm) channels does not differ significantly from zero below 3mHz, while a small difference of about 10° may exist at higher frequencies. Title: The helioseismological experiment at the Phobos interplanetary station - Preliminary results Authors: Froehlich, C.; Bonnet, R. M.; Bruns, A. V.; Vial, J. C.; Delaboudiniere, J. P.; Domingo, V.; Kollath, Z.; Kotov, V. A.; Rachkovskii, D. N.; Wehrli, Ch. Bibcode: 1991IzKry..83...22F Altcode: Preliminary results obtained from IPHIR (Interplanetary Helioseismology by Irradiance Measurements), a solar irradiance experiment on board the Soviet planetary mission Phobos-2, are presented. During the spacecraft's flight to Mars, the instrument gathered valuable data on tiny variations of solar irradiance over the course of six months. The data clearly show 5-min oscillations with relative amplitudes of about 10 exp -5 and with a well-defined pattern of discrete peaks in the power spectrum. The data of the red channel (it exhibited the lowest degradation of sensitivity over time) reveal remarkable temporal changes of amplitudes of discrete peaks within a period range of about 5 min, but with excellent frequency stability. Title: Desapariciones de filamentos solares como origen de sucesos de particulas y de los choques interplanetarios asociados. Authors: Heras, A. M.; Sanahuja, B.; Domingo, V. Bibcode: 1991BAOM...12...12H Altcode: No abstract at ADS Title: ESA's report to the 28th COSPAR meeting Authors: Chicarro, A.; Domingo, V.; Frisk, U. O.; Jakobsen, P.; Knott, K.; Kessler, M. F.; Lebreton, J. P.; Marsden, R.; Peacock, A.; Perryman, M. A. C. Bibcode: 1990STIN...9030141C Altcode: Ongoing and complete missions, including IUE, EXOSAT, Hipparcos and Giotto, are discussed. Projects under development, including Ulysses, Hubble Space Telescope, ISO (Infrared Space Observatory), the Solar Terrestrial Science Programme (STSP), Cassini/Huygens and the high throughput X ray spectroscopy mission (XMM), are reported. Missions under study are reviewed; the submillimeter spectroscopy mission (FIRST); Rosetta CNSR (Comet Nucleus Sample Return); third millenium Mars exploration, interferometry from space and Vulcan missions. The Eureca A and Columbus Polar Platforms are included. Title: Phase Differences Between Luminosity and Velocity Measurements of the Acoustic Modes Authors: Jiménez, A.; Álvarez, M.; Andersen, N. B.; Domingo, V.; Jones, A.; Pallé, P. L.; Roca Cortés, T. Bibcode: 1990SoPh..126....1J Altcode: With two photometric stations (Tenerife and Baja California) the luminosity p-mode spectrum at different wavelengths has been identified. After a coherence analysis between data from both stations to verify the solar origin of the peaks identified in luminosity, a comparative study with simultaneous velocity measurements (obtained at Tenerife only) has also been made. As a result the frequency dependence of the phase difference between luminosity and velocity p-modes has been obtained that is interpreted in terms of a nonadiabatic behaviour of the solar atmosphere. The amplitude ratios between luminosity and velocity p-modes have also been obtained. All these results are compared with theoretical expectations. Title: SOHO - an Observatory to Study the Solar Interior and the Solar Atmosphere Authors: Poland, A. I.; Domingo, V. Bibcode: 1990ASSL..166..277P Altcode: 1990oeob.coll..277P; 1990IAUCo.123..277P The Solar and Heliospheric Observatory (SOHO) is described. The two main objectives of SOHO are to improve understanding of solar coronal phenomena and to study solar structure and interior dynamics from its core to the photosphere. The primary goals of the coronal and solar wind studies are to understand the coronal heating mechanism and its expansion into the solar wind. These goals will be achieved both by remote sensing of the solar atmosphere with high resolution spectrometers and telescopes and by in situ measurement of the composition and energy of the resulting solar wind and the energetic particles that propagate through it. The structure and interior dynamics are to be studied by helioseismological methods and the measurement of solar irradiance variations. The SOHO spacecraft will be three-axis stabilized and located in a halo orbit around the L1 Lagrangian point (approximately 1 percent of the distance from the Earth to the Sun). It is currently scheduled for launch in July 1995. Title: The Soho Project and Helioseismology Authors: Domingo, Vicente Bibcode: 1990LNP...367..257D Altcode: 1990psss.conf..257D The Solar and heliospheric observatory (Soho) space mission being developed by ESA and NASA will carry together with other instruments devoted to the study of the solar atmosphere and solar wind, a set of instruments that will provide a comprehensive set of measurements of solar oscillations. Two investigations in Soho aim primarily at the study of g-modes and low l p-modes and a third one will have the central interest in high degree oscillations while aiming to extend the validity of its measurements to low 1 modes overlapping with the other two investigations. The Soho mission is being designed having into account the needs of the helioseismology experiments and therefore should be able to provide the best possible infrastructure for the production of good quality data. For the data analysis the three experiments will coordinate their operation and the data handling. It is expected that Soho will greatly profit of the experience gained with GONG, as a large fraction of the co-investigators in the Soho helioseismology investigations form part of the GONG project. The investigations in Soho have finished the definition phase of their instruments and the contractor selected by ESA has started on 1 December 1989 the industrial Phase B, or design phase, of the spacecraft and mission for a launch in March 1995. Title: Retrieval from Earth Orbit of the Ultra Heavy Cosmic Ray Experiment on the LDEF Spacecraft Authors: Thompson, A.; O'Sullivan, D.; Wenzel, K. -P.; Domingo, V.; Domingo, C.; Daly, J.; Smit, A. Bibcode: 1990ICRC....4..441T Altcode: 1990ICRC...21d.441T; 1989ICRC....4..441T No abstract at ADS Title: Energetic particles, interplanetary shocks and solar activity Authors: Domingo, V.; Sanahuja, B.; Heras, A. M. Bibcode: 1989AdSpR...9d.191D Altcode: 1989AdSpR...9..191D The study of the flow-pattern of energetic protons (35-1600 keV) associated with interplanetary shocks observed by ISEE-3, is analyzed as a function of the relative position of the spacecraft with respect to the shock and to the solar activity that has triggered the events, and is complemented with a statistical study on the thickness of bidirectional particle regimes associated with interplanetary shocks. The result indicates that the region behind the shock where the driver would be located extends over a wide angle around the longitude of the triggering event, with little asymmetry with respect to the propagation direction. Title: Solar Luminosity Oscillation Telescope (SLOT). Authors: Andersen, Bo Nyborg; Domingo, V.; Jones, A. R.; Korzennik, Sylvain G.; Jimenez, A.; Palle, Pere L.; Regulo, C.; Roca Cortés, Teodoro Bibcode: 1988ESASP.286..175A Altcode: 1988ssls.rept..175A Low degree l = 0-2 solar p-modes have been detected with the SLOT instruments at Izaña and Baja California. The main source of noise for these ground based observations is in the terrestrial atmosphere. However, the data acquisition system still has to have very slow intrinsic noise. The authors describe how this is achieved in the SLOT instruments. They also give a general description of the design and operating principles of the photometers and data acquisition system. Title: VIRGO: The solar monitor experiment on SOHO. Authors: Froehlich, C.; Andersen, Bo Nyborg; Berthomieu, G.; Crommelynck, D.; Delache, Philippe; Domingo, V.; Jimenez, A.; Jones, A. R.; Roca Cortés, Teodoro; Wehrli, Ch. Bibcode: 1988ESASP.286..371F Altcode: 1988ssls.rept..371F The VIRGO Experiment (Variability of solar Irradiance and Gravity Oscillations) contains two types of active cavity radiometers for monitoring of the solar "constant", two three channel sunphotometers (SPM) for the measurement of spectral irradiance at 335, 500 and 865 nm and a low resolution imager (LOI) with 12 pixels. The main scientific objective is probing the solar interior by helioseismology with p- and g-mode solar oscillations determined from spectral irradiance (SPM) and radiance (LOI) variations on time scales of minutes to the mission time. Moreover, the measurements of the variability of the solar "constant" and spectral irradiance over periods of days to the mission time will yield information about the convection zone, as will the comparison of the amplitudes and phases of the oscillations as manifested in irradiance and radiance (from VIRGO) and velocity (from GOLF and SOI). Title: Soho status. Authors: Domingo, V. Bibcode: 1988ESASP.286..363D Altcode: 1988ssls.rept..363D The scientific payload for Solar and Heliospheric Observatory (Soho) space mission has been selected. Soho will study the structure of the solar interior, the physics of the solar corona and the origin of the solar wind. The spacecraft definition phase will start in October 1989. The launch is expected for March 1995. Title: Solar luminosity oscillations from two stations and correlation with velocity measurements. Authors: Jimenez, A.; Palle, Pere L.; Roca Cortés, Teodoro; Andersen, N. B.; Domingo, V.; Jones, A. R.; Alvarez, M.; Ledezma, E. Bibcode: 1988ESASP.286..163J Altcode: 1988ssls.rept..163J Since 1984 the measurements of a quadrupole photometer sites at the Observatorio del Teide (Izaña, Tenerife) have made it possible to identify the p-mode luminosity spectrum with simultaneous velocity observations. Comparing this data, the adiabatic behaviour of solar atmosphere and theoretical expectations from solar models have been tested. Now, in order to increase the signal-to-noise ratio and reduce the sidebands due to the night-time data gaps, a second identical photometer was set-up in December 1987, at the Observatorio de San Pedro Mártir (Baja California Norte, Mexico). The first results of the observations of these two stations are analyzed and compared with simultaneous velocity measurements. Title: IPHIR: The helioseismology experiment on the PHOBOS mission. Authors: Fröhlich, C.; Bonnet, R. M.; Bruns, A. V.; Delaboudinière, J. P.; Domingo, V.; Kotov, V. A.; Kollath, Z.; Rashkovsky, D. N.; Toutain, T.; Vial, J. C.; Wehrli, C. Bibcode: 1988ESASP.286..359F Altcode: 1988ssls.rept..359F IPHIR (InterPlanetary Helioseismology by IRradiance measurements) is a solar irradiance experiment on the USSR planetary mission PHOBOS to Mars and its satellite Phobos. The experiment is a cooperative effort of PMOD/WRC, LPSP, SSD/ESA, KrAO and CRIP. The sensor is a three channel sunphotometer (SPM) which measures the solar spectral irradiance at 335, 500 and 865 nm with a precision of better than 1 ppm. A two axis solar sensor (TASS) is added to monitor the moderate solar pointing of the spacecraft. A microprocessor based data processing unit controls the sensor operation, acquires the data, and performs the data compression for the transmission at a mean rate of 1 bit/s. The two spacecrafts have been launched on July 7th and 12th, 1988. The experiment on PHOBOS I gathered data during 45 days before the S/C was lost, the one on PHOBOS II is still operating. The data recovery is excellent with virtually 100% coverage. Although the signal is disturbed by the pointing of the spacecraft the results of a preliminary analysis in the range of the 5-minutes oscillations demonstrate the improvement achievable due to the fact that the time series is truly continuous and the instrumental and sampling noise is very low. Title: Luminosity Oscillations Imager (LOI). Authors: Andersen, Bo Nyborg; Domingo, V.; Jones, A. R.; Jimenez, A.; Palle, Pere L.; Regulo, C.; Roca Cortés, Teodoro Bibcode: 1988ESASP.286..385A Altcode: 1988ssls.rept..385A The VIRGO (Variability in Irradiance and Gravity Oscillations) investigation has been selected to fly on ESA's SOHO mission. One of the components of the VIRGO is a small imaging solar photometer. This instrument, the Luminosity Oscillations Imager (LOI), will observe the solar radiance with 12 pixels resolution. A prototype of the LOI has been developed at ESTEC. This prototype was built mainly to test possible detector configurations, the data acquisition system and the internal guider. The prototype has been operating at Izaña, Tenerife since April this year. Title: SOHO: an observatory to study the solar interior and the solar atmosphere Authors: Domingo, V.; Poland, A. I. Bibcode: 1988sohi.rept....7D Altcode: The Solar and Heliospheric Observatory (SOHO) is described. The two main objectives of SOHO are to improve understanding of solar coronal phenomena and to study solar structure and interior dynamics from its core to the photosphere. The primary goals of the coronal and solar wind studies are to understand the coronal heating mechanism and its expansion into the solar wind. These goals will be achieved both by remote sensing of the solar atmosphere with high resolution spectrometers and telescopes and by in situ measurement of the composition and energy of the resulting solar wind and the energetic particles that propagate through it. The structure and interior dynamics are to be studied by helioseismological methods and the measurement of solar irradiance variations. The SOHO spacecraft will be three-axis stabilized and located in a halo orbit around the L1 Lagrangian point (approximately 1 percent of the distance from the Earth to the Sun). It is currently scheduled for launch in July 1995. Title: VIRGO: The solar monitor experiment on SOHO Authors: Froehlich, C.; Andersen, B. N.; Berthomieu, G.; Crommelynck, D.; Delache, Ph.; Domingo, V.; Jimenez, A.; Jones, A. R.; Roca Cortes, T.; Wehrli, Ch. Bibcode: 1988sohi.rept...19F Altcode: The Variability of solar IRradiance and Gravity Oscillations (VIRGO) experiment contains two types of active cavity radiometers for monitoring of the solar constant, two three channel sunphotometers for the measurement of spectral irradiance at 335, 500 and 865 nm and a low resolution imager with 12 pixels. The main scientific objective is probing the solar interior by helioseismology with p and g mode solar oscillations determined from spectral irradiance and radiance variations on time scales of minutes to the mission time. Information about the convection zone is thus obtained. The comparison of the amplitudes and phases of the oscillations as manifested in irradiance and radiance (from VIRGO) and velocity as measured by the GOLF (global oscillations at low frequencies) experiment are also used in analyzing the convection zone. Title: Diurnal photometric conditions at Teide observatory and long-term solar irradiance variations Authors: Andersen, B.; Domingo, V.; Jiménez, A.; Jones, A.; Korzennik, S.; Pallé, P. L.; Pérez Hernández, F.; Régulo, C.; Roca Cortés, T.; Tomás, L. L. Bibcode: 1988SoPh..116..391A Altcode: Monochromatic extinction coefficients at four wavelengths have been obtained over a period of more than two years at the Observatorio del Teide (Izaña Tenerife) using a full disc, direct sunlight, quadruple photometer devoted to the detection of integral luminosity oscillations of the Sun. The mean extinction coefficients (0.13 at 500 nm) show a seasonal variation of about 15%, the best atmospheric conditions being in winter and autumn. Moreover, in anyone day the extinction coefficient in the afternoon is always lower than the one in the morning by ∼ 7%. A one-year period fluctuation, with an amplitude of ∼ 0.035 mag, has been identified in the instrumental magnitudes outside the atmosphere, and is interpreted as the variation produced by the different Sun-Earth distance from winter to summer. Finally, the study made to detect periodic time fluctuations in both, Sun's magnitude and extinction coefficients, has given null results at levels of ∼ 0.04 and ∼ 1.8%, respectively. Title: ESA report to the 27th COSPAR meeting Authors: Domingo, V.; Fisk, U. O.; Grard, R.; Jakobsen, P.; Kessler, M. F.; Lebreton, J. -P.; Marsden, R.; Peacock, A.; Pedersen, A.; Perryman, M. A. C. Bibcode: 1988STIN...8830556D Altcode: The ISEE, IUE, EXOSAT, and Giotto missions are described. The status of the Ulysses, Hubble Space Telescope, HIPPARCOS, ISO, and solar-terrestrial science programs is discussed. The high throughput X-ray spectroscopy mission, submillimeter spectroscopy mission, and the comet nucleus sample return mission are presented. The CASSINI, GRASP, Lyman, Quasat, Vesta, and Giotto extended missions are introduced. The EURECA and Columbus space station programs are reviewed. Title: Low-energy particle events generated by solar disappearing filaments Authors: Heras, A. M.; Sanahuja, B.; Domingo, V.; Joselyn, J. A. Bibcode: 1988A&A...197..297H Altcode: Five large low-energy (E less than 2 MeV) proton events associated with interplanetary shocks, observed at 1 AU by the ISEE-3 probe, appeared to be triggered by solar disappearing filaments instead of solar flare activity. These events will join the other six events of this kind already known. In this paper these events are identified and a comparative study of the interplanetary proton for the nonflare and flaring situations is provided. Proton events that are triggered by disappearing filaments appears not to be associated with the strong X-ray or radio radiation that characterizes solar flares. Title: Diffuse Gamma Rays with Energies Greater than 1 X 10 14 eV Observed in the Southern Hemisphere Authors: Suga, K.; Toyoda, Y.; Kamata, K.; Murakami, K.; Lapointe, M.; Gaebler, J.; Escobar, I.; Saavedra, O.; Domingo, V.; Shibata, S.; Akiyama, H.; Takano, M.; Uchino, K. Bibcode: 1988ApJ...326.1036S Altcode: The data of extensive air showers with a low content of muons and hadrons, observed in the period 1964-1966 at Mount Chacaltaya in Bolivia, have been reanalyzed. Arrival directions of those showers selected so as to favor small initiation depths in the atmosphere (to enhance the contribution from gamma-ray-initiated showers) reveal a 3.8 sigma peak above an expected background from the region of alpha = 180-210 deg in the band of delta = 0 to -40 deg. The integral flux of diffuse gamma-rays above 1 x 10 to the 14th eV estimated from this excess is about 6.0 x 10 to the -12th/sq cm per sec per sr. In order to explain this very high flux, the possible contribution of gamma-rays from Loop 1 as well as the inverse Compton photons produced in the 2.7 K photon background as progeny of gamma-rays from Cyg X-3-like sources. Title: Cluster and SOHO: A joint endeavor by ESA and NASA to address problems in solar, heliospheric, and space plasma physics Authors: Schmidt, Rudolf; Domingo, Vicente; Shawhan, Stanley D.; Bohlin, David Bibcode: 1988EOSTr..69..177S Altcode: The NASA/ESA Solar-Terrestrial Science Program, which consists of the four-spacecraft cluster mission and the Solar and Heliospheric Observatory (SOHO), is examined. It is expected that the SOHO spacecraft will be launched in 1995 to study solar interior structure and the physical processes associated with the solar corona. The SOHO design, operation, data, and ground segment are discussed. The Cluster mission is designed to study small-scale structures in the earth's plasma environment. The Soviet Union is expected to contribute two additional spacecraft, which will be similar to Cluster in instrumentation and design. The capabilities, mission strategy, spacecraft design, payload, and ground segment of Cluster are discussed. Title: Correlation between velocity and luminosity measurements of solar oscillations Authors: Jimenez, A.; Palle, P. L.; Roca Cortes, T.; Domingo, V. Bibcode: 1988A&A...193..298J Altcode: Following the work started in 1984 to detect the solar intensity oscillations from ground (Jimenez et al., 1986), simultaneous velocity and intensity observations of 16 contiguous days of very high atmospheric quality obtained at Izana (Tenerife) have been analyzed. The frequencies of the p-mode intensity spectrum at three channels (500, 680 and 870 nm) and those of the velocity spectrum have been obtained. Amplitude ratios in the intensity measurements give results of 1.6 and 2.2 when comparing the last two channels with the first one, and their relative phases give a null result at any frequency in the 5 minute range. The relative phases between luminosity and intensity measurements give a mean result of -120 degrees. Finally, the ratio of the amplitudes of the intensity oscillations to the velocity ones correlates very well with theoretical expectations and it yields a fractional variation of the effective temperature of 2 x 10 to the -6th. Title: Groundbased Observations of Solar Luminosity Oscillations Authors: Andersen, B. N.; Domingo, V. Bibcode: 1988IAUS..123...67A Altcode: Results from ground based observations of low degree solar luminosity variations are presented. By using data from up to 15 consecutive excellent days the majority of the l = 0, 1 and 2 peaks in the region 2.5 - 3.5 mHz may marginally be identified. Title: The SOHO project: helioseismology investigations Authors: Domingo, V.; Poland, A. Bibcode: 1988AdSpR...8k.109D Altcode: 1988AdSpR...8..109D The solar and heliospheric observatory, Soho, will be placed into a halo orbit around the L1 Sun-Earth Lagrangian point in 1995. It will carry a set of instruments to study the physical phenomena in the solar atmosphere that heat the solar corona, the mechanisms by which the solar corona expands into the solar wind, and investigate the structure of the solar interior by the study of solar oscillations, both in velocity and in intensity (Helioseismology).

In this paper we describe the mission and the investigations to be carried out with the helioseismology instruments in the payload. A solar oscillations imager will measure velocity oscillations of degree up to 4000, while two other instruments will measure very long series of low degree modes of oscillation, one of them in velocity and the other in irradiance. The data obtained will be used to study the radial stratification and the longitudinal variation of the physical characteristics of the Sun, as well as many dynamical phenomena of the upper layers of the solar atmosphere. Title: Earthbased Observations of Solar Luminosity Oscillations Authors: Jimenez, A.; Palle, P. L.; Perez-Hernandez, F.; Regulo, C.; Roca-Cortes, T.; Domingo, V.; Korzennik, S. Bibcode: 1988IAUS..123...71J Altcode: Earth based multichannel photometry of integral sunlight has been obtained at Izaña (Tenerife) during 1984 - 1986. Power spectra of the solar luminosity variations of individual days show power in the 5 minute interval above noise at a level comparable to SMM data. When combining contigous days of data the signature of p mode solar oscillations spectrum appears, although individual peak identification is difficult. Title: Helioseismology from Space - the SOHO Project Authors: Domingo, V. Bibcode: 1988IAUS..123..545D Altcode: The Solar and Heliospheric Observatory (SOHO) has been proposed with the following aims: To investigate and understand the physical processes that form the solar corona, maintain it and give rise to the expanding solar wind, by high resolution spectroscopy of the chromosphere, transition region and corona in combination with "in situ" study of the resulting solar wind streams and associated fields; to investigate the solar interior structure by methods of helioseismology. It is foreseen that the spacecraft will be launched by the end of 1994. Title: Current Understanding and Issues on Electron Beam Injection in Space Authors: Poland, A. I.; Domingo, V. Bibcode: 1988AdSpR...8k.101P Altcode: 1988AdSpR...8Q.101P The Solar and Heliospheric Observatory (SOHO) satellite mission is planned to study the solar interior, to investigate the physical phenomena related to the formation of the solar corona and the solar wind, and to make in situ measurements of the solar wind. The SOHO instruments designed to study the solar atmosphere and the solar wind are described. The experiments include the study of solar UV radiation, a coronal diagnostic spectrometer, an extreme UV imaging telescope, a UV coronagraph spectrometer, a white light and spectrometric coronagraph, and a study of solar wind anisotropies. Title: Soho and Cluster - the scientific instruments. Authors: Domingo, V.; Schmidt, R.; Poland, A. I.; Goldstein, M. L. Bibcode: 1988ESABu..56...24D Altcode: The need to understand the complex processes that control the structure and dynamics of our daylight star and define the Earth's environment in space, has long been widely realised. Its continuing importance is reflected by the fact that twenty-three Principal Investigators and several hundred Co-Investigators from more than eighteen countries are now actively involved in the preparations for and execution of the Soho and Cluster missions. Title: Low-energy protons associated with interplanetary shocks as a coherent population Authors: Sanahuja, B.; Domingo, V. Bibcode: 1987JGR....92.7280S Altcode: We investigate the flow pattern of low-energy protons (35-1600 keV) associated with interplanetary shocks observed by ISEE-3 between August 1978 and April 1980. The analysis of the shape of the distribution function in the solar wind frame and its temporal evolution indicates that the low-energy protons can behave as a coherent, independent population of particles in the solar wind. Ahead of the shock this population propagates along the magnetic field in the same direction as the solar wind flow, while after the passage of the perturbed region associated with the shock, it propagates in the opposite sense. The behavior of the flow pattern of this population through the shock front is discussed for the 17 largest events observed in this period. Title: Extended Exposure for the Ultra Heavy Cosmic Ray Experiment on the LDEF Spacecraft Authors: Thompson, A.; O'Sullivan, D.; Domingo, C.; Wenzel, K. -P.; Domingo, V. Bibcode: 1987ICRC....2..402T Altcode: 1987ICRC...20b.402T; 1987ICRC....2..402D No abstract at ADS Title: UHE gamma-rays from Vela X-1 and Cen X-3. Authors: Suga, K.; Toyoda, Y.; Kamata, K.; Murakami, K.; Lapointe, M.; Gaebler, J.; Escobar, I.; Saavedra, O.; Domingo, V.; Shibata, S.; Akiyama, H.; Takano, M.; Uchino, K. Bibcode: 1987ICRC....1..277S Altcode: 1987ICRC...20a.277S No abstract at ADS Title: The solar-terrestrial science programme. Authors: Wenzel, K. -P.; Domingo, V.; Schmidt, R. Bibcode: 1987ESABu..50....8W Altcode: The prime objective of the STSP (solar-terrestrial science programme) Cornerstone is to attack outstanding scientific problems in solar, heliospheric and space plasma physics in a unified and co-ordinated manner. Title: Diffuse gamma-rays with energies greater than 1×1014eV observed in the southern hemisphere. Authors: Suga, K.; Toyoda, Y.; Kamata, K.; Murakami, K.; Lapointe, M.; Gaebler, J.; Escobar, I.; Saavedra, O.; Domingo, V.; Shibata, S.; Akiyama, H.; Takano, M.; Uchino, K. Bibcode: 1987ICRC....1..310S Altcode: 1987ICRC...20a.310S The data of extensive air showers with low content of muons and hadrons, observed in the period 1964 to 1966 at Mt. Chacaltaya have been reanalyzed. The authors try to explain the very high flux. Title: Ground-based measurements of solar intensity oscillations Authors: Jimenez, A.; Palle, P. L.; Roca Cortes, T.; Domingo, V.; Korzennik, S. Bibcode: 1987A&A...172..323J Altcode: Ground-based multichannel photometry of integral sunlight has been obtained at Izaña (Tenerife) during three months in 1984 with a photometer built at ESTEC. Power spectra of solar irradiance variations of individual days show power in the 5 min band just above noise at a level comparable to the one found from the SMM data (Woodard and Hudson, 1983). Previous similar ground work had never achieved the signal level required at the 5 min interval. When combining the best 7 contiguous days of data, the signature of p mode solar oscillations spectra appears, but individual identification is difficult due to a low signal-to-noise ratio. Title: Results of the solar constant experiment onboard Spacelab 1. Authors: Crommelynck, D. A.; Brusa, R. W.; Domingo, V. Bibcode: 1986SoPh..107....1C Altcode: 1987SoPh..107....1C A cavity type absolute radiometer was flown on Spacelab 1 in December 1983. We obtain a value of the solar constant of 1361.5 W m−2 with an estimated accuracy of ±2.3 W m−2 or 0.17%. When comparing this with other recent determinations, we find discrepancies which we consider indicative of metrological problems in present day absolute radiometry. Title: Low-energy particle events and solar filament eruptions Authors: Sanahuja, B.; Heras, A.; Domingo, V.; Joselyn, J. A. Bibcode: 1986AdSpR...6f.277S Altcode: 1986AdSpR...6..277S Over the period from August 1978 to October 1982, several large low-energy (E < 1.6 Mev) proton events associated with interplanetary travelling disturbances observed at 1 AU by ISEE-3, appeared not to be triggered by solar flares. Six of them can be associated with filament eruptions as the source of the disturbances. We have made a comparative study of the particle fluxes in the interplanetary medium, as well as of the available H-alpha observations and X-ray and radio emission, between these events and those associated with disturbances generated by solar flares. Title: The Ultra Heavy Cosmic Ray Experiment on LDEF-1 Authors: Osullivan, D.; Thompson, A.; Wenzel, K. -P.; Domingo, V. Bibcode: 1985crhe.work..302O Altcode: The DIAS-ESTEC ultraheavy-cosmic-ray experiment was deployed in earth orbit aboard the LDEF by the Space Shuttle on April 6, 1984. A large-area (12-sq m) solid-state nuclear-track-detector array, designed to study the charge spectrum of nuclei with Z = 30 or greater, is to remain in orbit until recovery of the LDEF by a second Shuttle mission in March 1985. Details of the background to the experiment, its astrophysical significance, analysis, and general expectations are discussed. The impact of recent results on the registration-temperature effect for ultraheavy nuclei on overall charge resolution is assessed. Title: Solar Irradiance Observations Authors: Crommelynck, D.; Domingo, V. Bibcode: 1984Sci...225..180C Altcode: The absolute radiometer on Spacelab 1 was used to obtain solar irradiance observations from space. A number of effects must be taken into account in the data reduction. A provisional value was obtained for the mean solar constant during the observation period (6 to 8 December 1983). Title: A high-resolution study of ultra-heavy cosmic-ray nuclei (A0178) Authors: O'Sullivan, D.; Thompson, A.; O'Ceallaigh, C.; Domingo, V.; Wenzel, K. P. Bibcode: 1984ldef.rept..101O Altcode: The main objective of the experiment is a detailed study of the charge spectra of ultraheavy cosmic-ray nuclei from zinc (Z = 30) to uranium (Z = 92) and beyond using solid-state track detectors. Special emphasis will be placed on the relative abundances in the region Z or - 65, which is thought to be dominated by r-process nucleosynthesis. Subsidiary objectives include the study of the cosmic-ray transiron spectrum a search for the postulated long-lived superheavy (SH) nuclei (Z or = 110), such as (110) SH294, in the contemporary cosmic radiation. The motivation behind the search for super-heavy nuclei is based on predicted half-lives that are short compared to the age of the Earth but long compared to the age of cosmic rays. The detection of such nuclei would have far-reaching consequences for nuclear structure theory. The sample of ultraheavy nuclei obtained in this experiment will provide unique opportunities for many tests concerning element nucleosynthesis, cosmic-ray acceleration, and cosmic-ray propagation. Title: Low-Energy Protons Associated with the 14-18 August 1979 Events (smy/stip Event no. Authors: Sanahuja, B.; Domingo, V.; Wenzel, K. -P. Bibcode: 1984sii..conf..195S Altcode: No abstract at ADS Title: Low-Energy Protons Associated with the 4 April 1980 Event (smy/stip Event no. 2.) Authors: Sanahuja, B.; Domingo, V.; Wenzel, K. -P. Bibcode: 1984sii..conf..229S Altcode: No abstract at ADS Title: Energetics and Interplanetary Effects of the August 14 and 18, 1979 Solar Flares: Summary of Observations Made during the Smy/stip Event no. Authors: Kane, S. R.; Bird, M. K.; Domingo, V.; Gapper, G. R.; Green, G.; Hewish, A.; Howard, R. A.; Iwers, B.; Jackson, B. V.; Koren, U.; Kunow, H.; McGuire, R. E.; Muller-Mellin, R.; Rompolt, B.; Sanahuja, B.; Sawant, H. S.; Stewart, R. T.; von Rosenvinge, T.; Wibberenz, G.; Zlobec, P. Bibcode: 1984sii..conf..175K Altcode: No abstract at ADS Title: The L1-lagrangian point orbit as a suitable site for helioseismologic measurements Authors: Domingo, V.; Wyn-Roberts, D. Bibcode: 1984MmSAI..55..375D Altcode: The orbit around the Earth - Sun Lagrangian point L1 has the advantages of providing continuous solar viewing and eliminating the Earth rotation velocity when compared with ground-based observations. ESA has completed a study on a spacecraft (DISCO) which was to have been placed in this orbit, and is now studying a potential solar observatory (SOHO) to be placed in the same orbit. The aims of SOHO are the understanding of the solar wind origin and of the heating and energy balance of the corona and the investigation of the solar interior structure. Title: An extensive solid state nuclear track detector array for the study of ultra heavy cosmic ray nuclei aboard the NASA Long Duration ExposureFacility (LDEF). Authors: Thompson, A.; O'Sullivan, D.; Wenzel, K. -P.; Domingo, V.; O'Ceallaigh, C.; Daly, J.; Smit, A. Bibcode: 1984NTRM....8..575T Altcode: No abstract at ADS Title: Low-Energy Protons Associated with the Events of 10 April, 24 April and 8 may 1981 (stip Interval Xii) Authors: Sanahuja, B.; Domingo, V. Bibcode: 1984sii..conf..307S Altcode: 1984STIA...8516082S One of the two flares of 10 April 1981 (1117 UT and 1650 UT) and the 24 April (1400 UT) and 8 May (2232 UT) produced interplanetary shocks that were accompanied by a large increase of low-energy protons (35-1600 keV). An interesting large shock event is observed on 11 April. Although the shocks are of very different characteristics, all have the common feature that the flow of particles up- and downstream is always from the shock, indicating the shock is the main proton acceleration source at this energy. Title: Low-energy protons associated with interplanetary shocks as an independent population in the solar wind Authors: Sanahuja, B.; Domingo, V. Bibcode: 1984AdSpR...4b.319S Altcode: 1984AdSpR...4..319S We investigate the large scale flow pattern of 36-1600 keV protons observed in association with several large interplanetary shocks on ISEE-3 between August 1978 and April 1980. The distribution function in the solar wind frame and its temperal evolution indicates that these particles can behave as a coherent population in the solar wind. This population propagates along the magnetic field in the same direction as the solar wind flow, ahead of the shock, and in the opposite direction after the passage of the perturbed region associated with the shock. Title: The Ultra Heavy Cosmic Ray Experiments on the NASA Long Duration Exposure Facility (ldef) Authors: O'Sullivan, D.; Thompson, A.; Daly, J.; O'Ceallaigh, C.; Wenzel, K. P.; Domingo, V.; Smit, A. Bibcode: 1983ICRC....9..403O Altcode: 1983ICRC...18i.403O A large array (≅20 m2sr) of solid state nuclear track detectors is being prepared for a twelve month exposure in earth orbit aboard the NASA LDEF. The experiment is designed to study the charge spectrum of cosmic ray nuclei with Z > 30, particularly of those above Z ≡ 70. Title: The Ultra Heavy Cosmic Ray Experiment on the NASA Long Duration Exposure Facility (ldef) Authors: O'Sullivan, D.; Thompson, A.; Daly, J.; O'Ceallaigh, C.; Wenzel, K. P.; Domingo, V.; Smit, A. Bibcode: 1983ICRC....8..126O Altcode: 1983ICRC...18h.126O The experiment is designed primarily to investigate the charge spectrum of cosmic ray nuclei with Z greater than or equal to 30. This is to be done by obtaining a larger sample of events than has hitherto been possible by balloon or satellite exposures. A very large array of solid state nuclear track detectors is to be exposed in space for approximately one year. Special emphasis will be placed on the relative abundances in the region where Z is greater than or equal to 65, which is thought to be dominated by r-process nucleosynthesis. Among the subsidiary objectives of the experiment are the study of the cosmic ray transition spectrum and a search for the postulated long-lived superheavy nucley (Z greater than or equal to 110) in the contemporary cosmic radiation. It is noted that the search for super-heavy nuclei is based on predicted half-lives that are short in comparison with the age of the earth but long in comparison with the age of cosmic rays. The far-reaching consequences for nuclear structure theory that the detection of such nuclei would have are noted. Title: Report on the scientific satellites of the European Space Agency Authors: Burke, W. R.; Bennett, K.; Benvenuti, P.; Domingo, V.; Emery, R. J.; de Graauw, T.; Knott, K.; Macchetto, F.; Marsden, R. G.; Page, D. E. Bibcode: 1983STIN...8332831B Altcode: The missions and status of Cos-B Geos 1 and 2, ISEE, and IUE are outlined. The first Spacelab payload; EXOSAT; and the International Solar Polar Mission are described. The ESA contribution to the Space Telescope program; the Hipparcos astrometry program; the Giotto Halley's Comet mission; and the Infrared Space Observatory project are described. Title: A Large Proton Event Associated with Solar Filament Activity Authors: Sanahuja, B.; Domingo, V.; Wenzel, K. -P.; Joselyn, J. A.; Keppler, E. Bibcode: 1983SoPh...84..321S Altcode: We report observations made from several interplanetary spacecraft, of the large low-energy particle event of 23-27 April, 1979 associated with solar filament activity. We discuss the intensity, spectral and directional evolution of the event as observed in the energy range 35-1600 keV on ISEE-3, located ∼ 0.99 AU from the Sun upstream of the Earth. We demonstrate that the shock disturbance propagating through the interplanetary medium and observed at ISEE-3 on 24/25 April strongly controls the particle event. From a comparison of the ISEE-3 observations with those on other spacecraft, in particular on Helios-2, located at 0.41 AU heliocentric distance near the Sun-Earth line, we identify the solar filament erupting on late 22 April near central meridian as the trigger for the propagating shock disturbance. Title: La magnetosfera terrestre. Un acelerador de partículas cargadas. Authors: Domingo, V. Bibcode: 1983POEM...14...83D Altcode: No abstract at ADS Title: Energetics and interplanetary effects of the August 14 and 18, 1979 solar flares Authors: Kane, S. R.; Bird, M. K.; Domingo, V.; Green, G.; Gapper, G. R.; Hewish, A.; Howard, R. A.; Iwers, B.; Jackson, B. V.; Koren, U. Bibcode: 1983STIN...8329164K Altcode: The STIP Event No. 1, which covered the time interval August 14 - 18, 1979, was characterized by two energetic flares: one on August 14 (approximately 1243 UT) and the other on August 18 (approximately 1400 UT). The hard X-ray, soft X-ray, optical, radio and energetic particle emissions from these flares and their interplanetary effects were observed with many instruments in space and on the ground. A summary of some of these observations is presented. The results of a preliminary analysis relevant to the acceleration of particles, coronal transients and evolution of shocks are as follows: (1) During the August 14 flare energetic particles were probably accelerated but could not escape the Sun in large numbers. On the other hand, during the August 18 flare the acceleration of high energy particles occurred relatively high in the corona, from whence they could easily escape into interplanetary space but could not penetrate down to the lower altitudes in the solar atmosphere in large numbers. (2) The kinetic energy of the coronal transient associated with the August 14 flare was much larger than the total energy of energetic electrons, indicating an additional energy source for the transient. (3) The shock associated with the August 18 flare extended to greater than 2 (3.14) steradians. The shock maintained its speed from the flare site to a distance of approximately 35 R and then decelerated to a distance of approximately 1 AU as approximately R to the minus 0.8 power. Title: Disco - a solar-seismology and heliospheric-structure observatory. Authors: Domingo, V. Bibcode: 1982ESABu..32...16D Altcode: No abstract at ADS Title: Consequences of solar-related processes on the earth's environment and man's devices. Authors: Gendrin, R.; Domingo, V. Bibcode: 1982sspf.conf...71G Altcode: No abstract at ADS Title: Consequences of solar-related processes on the Earth's environment and man's devices Authors: Gendrin, R.; Domingo, V. Bibcode: 1982AdSpR...2a..71G Altcode: 1982AdSpR...2...71G The effects of solar disturbances on the earth environment and on anthropogenic systems and devices are discussed. Attention is given to solar cosmic ray effects on the atmosphere, which may produce an increase in D region electron density giving rise to polar cap absorption events, modulations of galactic cosmic ray flux affecting atmospheric electric fields, and solar wind-ionosphere coupling which may exert an influence on terrestrial meteorology. Solar wind effects on the magnetosphere-ionosphere-atmosphere system as evidenced by the auroral electrojet, magnetospheric substorms and auroral heating are then considered in relation to their consequences for large, conducting man-made systems and geomagnetic surveys at high latitudes, spacecraft charging and performance and satellite lifetimes. The effects of human activities, both scientific and industrial, on the magnetosphere are also pointed out. Title: The Solar Grazing Incidence / GRIST / and Optical / SOT = Solar Optical Telescope / Joint Accommodations Authors: Domingo, V. Bibcode: 1981SSRv...29..327D Altcode: Some of the problems foreseen for the joint accommodation and operation of the Grazing Incidence Solar Telescope (GRIST) under study by ESA to operate in the extreme ultraviolet region (90 < λ < 1700 Å), and the Solar Optical Telescope (SOT), developed by NASA to operate in the ultraviolet, optical and infrared region (A > 1100 Å) on a Spacelab mission are described. Title: Physics of solar variations Authors: Domingo, V. Bibcode: 1981SoPh...74.....D Altcode: Topics discussed include the sun (structure, oscillations, magnetic cycle, surface variations), solar radiation, solar radiation effects in the earth's atmosphere, long-term variations (climate and paleoclimate), and instrumentation. Papers are presented on short-period intensity fluctuations of integral sunlight, on the theory of the solar cycle, and on the nonsymmetric solar dynamo. Attention is also given to solar radiation and its variation in time, to the effects of solar variations on the upper atmosphere, and to the role of space techniques in understanding solar variability. Title: Introduction - Physics of Solar Variations Authors: Domingo, V. Bibcode: 1981SoPh...74....7D Altcode: No abstract at ADS Title: On the location of the source for the energetic electron layer at the polar magnetopause and its relation to magnetic reconnection Authors: Formisano, V.; Domingo, V.; Wenzel, K. -P. Bibcode: 1981JGR....86.4579F Altcode: The existence of a layer of energetic (>20 keV) electrons along the magnetopause, extending from the polar cusp region to the distant magnetotail, has been established by measurements on various spacecraft. We have performed a statistical study of electron flux and spectral measurements above 0.5 MeV observed in different regions of the magnetopause accessible to HEOS 2, with the aim of identifying the source for this magnetopause electron layer. The measurements along the polar magnetotail (i. e., adjacent to the plasma mantle), along the mid-latitude dayside magnetopause (i.e.,adjacent to the dayside plasma boundary layer), and on both sides of the magnetosheath/polar cusp interface (i.e., in the exterior polar cusp and in the entry layer) have been separately analyzed and are statistically compared. We conclude that escape of electrons from the magnetosphere can be excluded as a significant source for the tail magnetopause layer on the basis of the observed intensities, of the spectra, and of the frequency of appearance of electrons outside those magnetopause regions which lie adjacent to the outer trapping zone. The electron intensities in the exterior polar cusp region are found to be correlated with the north/south component of the interplanetary magnetic field (IMF). High intensity levels are observed when the IMF is directed southward (Bz<0), and low levels when the IMF points northward (Bz>0). The electron flux in the exterior cusp region at times of southward IMF and at the near-earth polar magnetotail at times of northward IMF is well correlated with the number of field lines carried by the solar wind towards the magnetosphere (expressed by the product of solar wind speed and interplanetary field magnitude). We interpret this as strong evidence that acceleration processes associated with magnetic reconnection occur at the magnetopause at those times. Local acceleration near the high-latitude magnetopause appears therefore to be a prime source for the magnetopause electron layer. Title: Non-Flare Injection of Protons Into Interplanetary Space Authors: Domingo, V.; Sanahuja, B.; Wenzel, K. -P. Bibcode: 1981ICRC....3..109D Altcode: 1981ICRC...17c.109D The superimposition of a second proton population associated with a solar wind regime, and bounded by a pair of shocks, is found to be superimposed upon the first in an investigation of 35-1600 KeV solar protons observed during an April, 1979 nonflare event by ISEE-3. The source of the particles and the solar wind regime appear to be closely associated with intense solar filament activity near the central meridian. The temporal evolution of velocity spectra and anisotropy distributions during this period are discussed. Title: Anisotropy Characteristics of Upstream Proton Events Authors: Sanderson, T. R.; Domingo, V.; Reinhard, R.; Wenzel, K. -P. Bibcode: 1981ICRC....3..483S Altcode: 1981ICRC...17c.483S Results are presented of a detailed analysis of proton anisotropies observed during an upstream event when ISEE-3 was approximately 80 earth radii upstream from the earth, and close to the sun-earth radial. During the first part of the event, particles were observed streaming mainly from the direction of the earth along the magnetic field. Later in the event, the angular distributions broadened until towards the end of the event, approximately equal intensities were observed with pitch angles from 0 deg up to 120 deg, with essentially no particles with pitch angles close to 180 deg. (Here a 0 deg pitch angle particle is defined as a particle moving upstream along the magnetic field.) Large amplitude low-frequency waves were observed in the magnetic field at ISEE-3 whenever enhanced fluxes of 90 deg protons were observed. It is argued that the 90 deg protons are the result of pitch angle scattering of the upstream moving protons in the region between the bow shock and ISEE-3. Title: Propagation of upstream protons in the near-earth solar wind Authors: Domingo, V.; Sanderson, T. R.; Wenzel, K. -P. Bibcode: 1981AdSpR...1c.125D Altcode: 1981AdSpR...1..125D The propagation of energetic protons (35-1600 keV) from the Earth's magnetosphere to the ISEE-3 spacecraft located about 240 earth radii (RE) upstream in the solar wind is used as a tool to study the interaction between these protons and the solar wind. In this preliminary study we present proton pitch angle distributions seen at different times during the development of upstream events that occur in relatively quiet interplanetary conditions. In general a highly anisotropic sunward flow is seen at the beginning of the events. During the course of the events pitch angle distributions may vary between streaming along the field lines (peaked around 0° pitch angle), a uniform intensity between 0° and 90°, and a peaked distribution around a preferred pitch angle that is often near 90°. Title: Propagation of upstream protons in near-earth solar wind. Authors: Domingo, V.; Sanderson, T. R.; Wenzel, K. -P. Bibcode: 1981crh..conf..125D Altcode: No abstract at ADS Title: Control of Energetic Particle Flows by the Interplanetary Magnetic Field Structure Authors: Reinhard, R.; Formisano, V.; Wenzel, K. P.; Domingo, V. Bibcode: 1981sowi.conf..490R Altcode: No abstract at ADS Title: Intensity Decay Patterns for Proton Particle Increases Associated with Interplanetary Shock Waves Authors: Hynds, R. J.; Domingo, V. Bibcode: 1981ICRC....3..447H Altcode: 1981ICRC...17c.447H At 1 AU the passage of interplanetary shock waves is associated with long-time, constant increases in intensity of low energy protons, called Energetic Storm Particle (ESP) events. The characteristc pattern involves an initial rise in particle intensity up to 12 hours prior to the passage of the shock; the intensity peaks at or near the shock front, followed by a relative smooth decay after the passage of the shock. For protons of energies less than or equal to 30 keV, the intensity decay after the passage of the shock can show considerable variation. The particle data are compared to interplanetary magnetic field and solar wind data, showing that these abrupt changes in intensity are associated with interplanetary plasma and field conditions. Data from the Energetic Proton Anisotropy Spectrometer on the ISEE-3 spacecraft is used to investigate a typical ESP event (February 17-23, 1979). Title: Prediction of energetic particle disturbances Authors: Paulikas, G. A.; Baker, D. N.; Barron, W. R.; Domingo, V.; Higbie, P. R.; Imhof, W. L.; Lyons, L. R.; McPherron, R. L.; Roelof, E. C.; Scholer, M. Bibcode: 1979stp.....2..415P Altcode: The prediction of fluxes of energetic particles of solar or magnetospheric origin is addressed. Topics include the prediction of the properties of the particle populations generated by magnetospheric storms and substorms, and the prediction of long term variations in the populations of magnetospheric particles. Title: Energetic Electrons in the Cusp and in the High Latitude Plasma Sheet - Evidence for Source Regions Authors: Formisano, V.; Domingo, V. Bibcode: 1979P&SS...27.1479F Altcode: HEOS-2 has observed energetic electrons (> 40 keV) in the high latitude magnetosphere appearing as one or more peaks outside and often well separated from the trapping boundary. Most of the observations are between 70° and 80° invariant latitudes both in the day and nightside. The peaks are located in the dayside adjacent to the polar cusp and coincide in the nightside with the edge of the plasma sheet. The electron peak intensity on the nightside shows a clear correlation with AE. The electron peak intensities on the dayside exceed those on the nightside and are generally higher in the pre-noon than in the afternoon sector. Observations on the dayside in the distant cusp region and in the adjacent magnetosheath show high and fluctuating intensities of energetic electronswith an energy spectrum much harder than in the outermost trapping region. This observational evidence suggests different source regions for these energetic electrons: one in the distant geomagnetic tail and another one around the dayside cusp indentation. Title: The three-dimensional shape of the magnetopause Authors: Formisano, V.; Domingo, V.; Wenzel, K. -P. Bibcode: 1979P&SS...27.1137F Altcode: Nearly 1000 magnetopause crossings from HEOS-2, HEOS-1, OGO-5 and 5 IMP space-craft covering most of the northern and part of the southern dayside and near-Earth tail magnetopause ( X >-15 RE) have been used to perform a detailed study of the three-dimensional shape and location of the magnetopause. The long-term influence of the solar wind conditions on the average magnetopause geometry has been reduced by normalising the radial distances of the observed magnetopause crossings to an average dynamical solar wind pressure. Best-fit ellipsoids have been obtained to represent the average magnetopause surface in geocentric solar ecliptic (GSE) and (as a function of tilt angle) in solar magnetic (SM) coordinates. Average geocentric distances to the magnetopause for the 1972-1973 solar wind conditions (density 9.4 cm -3, velocity 450 km s -1) are 8.8 RE in the sunward direction, 14.7 RE in the dusk direction, 13.4 RE in the dawn direction and 13.7 RE in the direction normal to the ecliptic plane. The magnetopause surface is tilted by 6.6° ± 2° in a direction consistent with that expected from the aberration effect of the radial solar wind. Our data suggest that the solar wind plasma density and the interplanetary magnetic field (IMF) orientation affect the distance to the polar magnetopause, larger distances corresponding to higher plasma density and southward fields. Our best-fit magnetopause surface shows larger geocentric distances than predicted by the model of Choe et al. [ Planet Space Sci. 21, 485 (1973).] normalised to the same solar wind pressure. Title: Total Solar Energy Output and its Measurement Authors: Domingo, V. Bibcode: 1979BAAS...11..423D Altcode: No abstract at ADS Title: Total solar energy output and its measurement. Authors: Domingo, V. Bibcode: 1979BAAS...11..422D Altcode: No abstract at ADS Title: Magnetospheric Bursts at Proton Energies above 35 KEV. Observed from the ISEE-3 Spacecraft Authors: Hynds, R. J.; Balogh, A.; Domingo, V.; Wenzel, K. -P. Bibcode: 1979ICRC....3..154H Altcode: 1979ICRC...16c.154H No abstract at ADS Title: a High Resolution Study of Ultra Heavy Cosmic Ray Nuclei Using the Long Duration Exposure Facility (ldef) Authors: Thompson, A.; O'Sullivan, D.; Daly, J.; O'Ceallaigh, C.; Domingo, V.; Smit, A.; Wenzel, K. -P. Bibcode: 1979ICRC...11..103T Altcode: 1980ICRC...11..103T; 1979ICRC...16k.103T A large array of nuclear track detectors is being prepared for a twelve month exposure in space aboard the LDEF which is scheduled to be launched by the NASA Space Shuttle in 1981. The experiment is designed to study the charge spectrum of cosmic ray nuclei with Z greater than 30 by obtaining a large and more uniform sample of events than has hitherto been possible by balloon or satellite exposures. A summary of the astrophysical significance of the experiment and its current state of development is given. Title: a Solar Proton Event of Possible Non-Flare Origin Authors: Domingo, V.; Hynds, R. J.; Stevens, G. Bibcode: 1979ICRC....5..192D Altcode: 1979ICRC...16e.192D; 1980ICRC....5..192D The sun showed little activity in the period August 18-23, 1978. A filament, near central meridian passage, disappeared at approximately 0120 U.T. on August 23, with a SSC recorded at earth at 0247 U.T. on August 27 that appears to be associated with it. On August 25, the low-energy proton detector on board the ISEE-3 spacecraft detected a particle increase which commenced prior to mid-day, and lasted until about 1730 U.T. on August 27. Data for the event are displayed and the possible origin of the particles is discussed. Title: Rigidity-independent coronal propagation and escape of solar protons and α particles Authors: Perron, C.; Domingo, V.; Reinhard, R.; Wenzel, K. -P. Bibcode: 1978JGR....83.2017P Altcode: A statistical study of 42 solar proton and α particle events has been performed in the energy range of 9-36MeV/nucleon (nuc) as measured by the Space Science Department/European Space Agency experiment on Heos 2 during 1972-1974. From one event to another there is a high variability of the p/α ratio at equal energy per nucleon ranging from about 4 to 1000 at 10 MeV/nuc. It is found that the lower value of the p/α ratios increases with azimuthal distance from the flare site. We show that this is not the result of rigidity-dependent coronal processes but that the increase follows rather as a consequence of two observations: (1) the p/α ratio is correlated with the size of the particle event (Van Hollebeke, 1975) and (2) the number of observed particle events decreases to the east as is found by numerous authors. A model calculation based on these observations is in good agreement with the data. The conclusion of rigidity-independent coronal propagation and escape also follows from other observations. First, the p/α ratios simultaneously measured by the University of Chicago experiment on board Pioneer 10 and 11, which have different connection longitudes, are generally the same as the Heos 2 values. Second, no systematic variation of the p/α ratio is found for the few cases of large individual events, when the p/α ratio can be followed over an extended time period, i.e., over an extended range of connection longitudes. Third, the proton and α particle spectral exponents show no systematic variation with heliolongitude. It is concluded that the observed large variations of the p/α ratio from event to event are essentially due to different acceleration or storage conditons at the flare site. Title: Where do charged particles enter in and exit from the magnetosphere? Some HEOS-2 measurements. Authors: Domingo, V.; Page, D. E.; Wenzel, K. -P. Bibcode: 1978JATP...40..279D Altcode: The orbit of HEOS-2 through the northern polar magnetosphere was such that it was possible to monitor the motion of solar protons at the polar magnetopause and across the geomagnetic tail. The large-particle intensity was found to increase as the magnetopause was approached. The inner magnetosphere appears to be partially shielded by the magnetopause from solar particles. The characteristics of an essentially permanent layer of energetic and relativistic electrons were also monitored by HEOS-2. This layer was detected in about 90% of the orbits over a period of 25 months. It was located at or around the magnetopause. The electron intensity in the magnetopause spike seems to fall off with distance along the tail away from the earth. This is consistent with the idea that the electrons originate near the earth. Title: On the mechanism of plasma penetration and energetic electron escape across the dayside magnetopause. Authors: Formisano, V.; Domingo, V.; Wenzel, K. -P. Bibcode: 1978JATP...40..293F Altcode: A statistical study of correlated observations of plasma, energetic (above 40 keV) electrons and magnetic fields on HEOS-2 in the outer dayside magnetosphere and magnetosheath has been performed. It is found that on the dayside magnetosphere the occurrence of plasma inside the magnetopause is anticorrelated with the appearance of energetic electrons in the magnetosheath. A mechanism is derived that attempts to explain how plasma may penetrate across the magnetopause into the magnetosphere and how energetic electrons may escape from the (pseudo) trapping region in the dayside magnetosphere into the magnetosheath. The mechanism is an E X B drift across the magnetopause. The drift is directed inward or outward depending on the direction of the electric field at the magnetopause. Title: Interplanetary magnetic field and geomagnetic activity. Authors: Domingo, V. Bibcode: 1978spre.conf..325D Altcode: 1978spre.proc..325D The interaction between the interplanetary magnetic field (IMF) and the geomagnetic field is investigated using a compilation of 34,670 hr of data on IMF and solar-wind parameters, as well as the Kp index as an indicator of geomagnetic activity. Correlations between geomagnetic activity and solar-wind parameters are analyzed, and it is found that geomagnetic activity is apparently only indirectly related to the interaction between the IMF and the geomagnetic field. The results indicate that the interaction between the geomagnetic field and the IMF dominates the solar-wind interaction with the magnetosphere, is governed by folding of the IMF lines of force around the magnetosphere, and extends throughout the magnetopause. Title: Energetic electrons in the outer magnetosphere at mid to high latitudes Authors: Domingo, V.; Wenzel, K. -P. Bibcode: 1978spre.conf..313D Altcode: 1978spre.proc..313D Results are reported for coordinated HEOS 2 electron and magnetic-field observations in the zone of unstable (variable) radiation at middle to high latitudes in the northern magnetosphere. The observations are discussed in terms of dayside closed field lines, the flanks of the magnetotail, and the distribution of variable electron fluxes observed in the outer magnetosphere. It is found that: (1) the electron population of the dayside pseudotrapping region extends out to the magnetopause at medium and high latitudes; (2) in the flanks of the magnetotail the electron population extends to high latitudes along the horns discovered at low latitudes by Frank et al. (1963); (3) the horn on the morning side appears to be populated by higher electron intensities and to extend to higher latitudes than that on the evening side; and (4) the electron fluxes in the flanks of the magnetotail appear to be a continuation of those encountered in the dayside pseudotrapping region and exhibit properties similar to those observed for electrons encountered in the magnetopause electron layer and in the magnetosheath. Title: Influence of the magnetosheath on solar proton penetration into the magnetosphere Authors: Domingo, V.; Wenzel, K. -P. Bibcode: 1977P&SS...25.1111D Altcode: The observation of solar protons (1-9 MeV) aboard HEOS-2 in the high-latitude magnetotail and magnetosheath on 9 June 1972, and their comparison with simultaneous measurements on Explorers 41 and 43, both in interplanetary space, indicate the existence of a distinct region of the inner magnetosheath (about 3 Earth radii thick) near the high-latitude magnetopause in which the solar particle flow is almost reversed with respect to the flow observed in interplanetary space. The region can also be seen by comparing magnetic field measurements on the three spacecraft. The observations in the outer layer of the magnetotail show solar protons predominantly entering the magnetosphere somewhere near the Earth, perhaps the cusp region. Title: Energetic and relativistic electrons near the polar magnetopause Authors: Domingo, V.; Page, D. E.; Wenzel, K. -P. Bibcode: 1977JGR....82.2327D Altcode: More than 2 years of Heos 2 observations in the high-latitude outer magnetosphere and magnetosheath have confirmed the presence of a layer of energetic and relativistic electrons near the polar tail magnetopause. This layer, appearing as ‘electron spike’ on almost every magnetopause crossing, contains electrons over a wide range of energies up to relativistic energies of >2 MeV. Their differential energy spectrum, if fitted by a power law, has an average spectral index between 3 and 4.5. The spikes are typically 1-2 RE wide extending more into the magnetosheath than into the magnetosphere. The electron intensity in the magnetopause layer decreases with distance along the tail, away from the polar cusp, and increases with increasing Kp values. It tends to be higher when the magnetosheath field is parallel or antiparallel to the tail magnetic field. In many cases the magnetopause spikes are accompanied by spikes in the magnetosheath which often follow closely the fluctuations of the magnetosheath field direction and/or intensity. A map of the average electron distribution in the polar magnetosphere and magnetosheath is presented. Title: Interplanetary magnetic field and geomagnetic activity Authors: Domingo, V. Bibcode: 1977IA&A...29...11D Altcode: A vectorial treatment of the geomagnetic field and interplanetary magnetic field (IMF) is attempted with the object of shedding light on interaction between the fields. Advantages and drawbacks of the three-hour planetary index Kp are considered; the Kp is relied upon in the analysis. Data referable to nearly 35,000 hours during which the velocity of the fields were observable are considered. The kinetic effects of the solar wind perceived in terms of solar wind velocity are found independent of electromagnetic effects. The interaction between the IMF and the geomagnetic field is found maximized when the fields are antiparallel in the equatorial zone and minimized when the angle formed between them is in the 30-50 deg range, and is an increasing function of the intensity of the IMF. Title: The March 5, 1972 Solar Event: Coronal Control of Particle Release Authors: Reinhard, R.; Domingo, V.; Perron, C.; Wenzel, K. -P. Bibcode: 1977ICRC....5..107R Altcode: 1978ICRC....5..107R; 1977ICRC...15e.107R The time-intensity profiles of 1-9-MeV and 9-36-MeV protons observed by the ESA/SSD detector system on HEOS 2 during the March 5, 1972, event display a number of unusual features. The most prominent is a plateaulike peak lasting for almost a day. When mapping the particle fluxes back to the sun, it is seen that the plateau is caused by a large chromospheric polarity cell which is 60 to 100 deg away from the acceleration region and uniformly populated with particles. A short-lived (3 h) particle intensity increase with strong sunward flow is observed during the decay phase and tentatively associated with a magnetic loop-type structure in the interplanetary medium. Title: Rigidity Independent Coronal Propagation and Escape of Solar Protons and Alpha Particles Authors: Perron, C.; Domingo, V.; Reinhard, R.; Wenzel, K. -P. Bibcode: 1977ICRC....5..113P Altcode: 1977ICRC...15e.113P No abstract at ADS Title: Generation and propagation of charged particles in the solar event of 22 July 1972. Authors: Morosova, E. I.; Pisarenko, N. F.; Volodichev, N. N.; Kolesov, G. Ia.; Kurt, V. G.; Domingo, V.; Page, D. E.; Wenzel, K. -P.; Smerd, S. F. Bibcode: 1976spre.conf..775M Altcode: 1976spre.proc..775M The increase of charged particles, protons with energies up to 500 MeV and electrons up to about 3.5 MeV, in the solar event on 22 July 1972 is examined. The analysis of the data on the anisotropy of the charged particles, radio and X-ray observations, and the absence of an optical flare lead to the conclusion that the increase is associated with a sympathetic flare in the active region McMath 11958. The powerful shock wave from the flare, which occurred behind the limb apparently in the active region McMath 11976, moving along the sun's surface was the agent which caused this flare. The capture of some of the flare particles by a trap near the sun led to the possibility of their prolonged escape into the interplanetary space. Title: Experimental evidence for solar protons following paths determined by solar wind flow regimes. Authors: Wenzel, K. -P.; Domingo, V.; Page, D. E. Bibcode: 1976spre.conf..719W Altcode: 1976spre.proc..719W Experimental results are presented from the solar particle, plasma and magnetometer experiments on HEOS 2 indicating that solar protons are constrained to discrete solar wind flow regimes and only with difficulty move across magnetic field lines to neighboring regimes. An outstanding example was the period of 29 October-2 November 1972, during which time HEOS 2 appeared to remain close to a solar wind boundary lying roughly parallel to the ecliptic plane. Another example of proton collimation in solar wind regimes was observed during 3-5 November 1973. Title: October 1972 solar event: The third dimension in solar particle propagation Authors: Domingo, V.; Page, D. E.; Wenzel, K. -P. Bibcode: 1976JGR....81...43D Altcode: From late on October 29 until November 3, 1972, our experiment on the European Space Research Organization satellite Heos 2 recorded the arrival of an enhanced interplanetary particle intensity. A dramatic ‘slot’ in count rate and other sudden anisotropy and flux changes (measured in and perpendicular to the ecliptic plane) were found to coincide with changes in the θ (north-south) ecliptic direction of the interplanetary magnetic field. However, reorientation of strongly field-aligned particle distributions relative to the detectors was insufficient to explain the intensity changes recorded, and the conclusion had to be drawn that the spacecraft was repeatedly crossing a boundary between one regime and a neighboring one with a different particle population. Since the switching from one regime to the other continued for several days, it would seem reasonable to suggest that the boundary between regimes was roughly parallel to the ecliptic plane. This idea was reinforced by the discovery that each time that the particle regime changed, not only did Bθ change, but the solar wind flow direction changed, the dip angle reversing sign. It would thus appear that when the solar wind blows three-dimensional snakelike tubes in interplanetary space, MeV particles obediently follow the field line bundles within such tubes and experience considerable difficulty in crossing from one tube to a neighboring tube which encloses a different regime. Because of the absence of cross-field particle movement, measurements made at higher solar latitudes, where most solar active regions occur, could reveal a somewhat different picture of the development of solar particle events. Title: Solar Radiation Variation and Climate Authors: Domingo, V. Bibcode: 1976ASSL...61...21D Altcode: 1976aps..conf...21D No abstract at ADS Title: Multisatellite observations of solar protons penetrating the magnetopause. Authors: Domingo, V.; Page, D. E.; Wenzel, K. -P. Bibcode: 1976ASSL...57..225D Altcode: Simultaneous observations of low-energy solar protons (1-40 MeV) by HEOS-2 in the northern high-latitude magnetotail and by other spacecraft in interplanetary space during the solar proton event of June 8, 1972 are presented. The results indicate that solar protons enter that magnetotail lobe which is not well connected to the interplanetary magnetic field - with respect to solar-particle entry - preferentially close to the earth rather than farther downtail. The particle density gradients measured in the tail lobe suggest that the particles enter there not only across the polar magnetopause, but also from the neutral sheet. Title: On the Propagation of Low Energy Solar Protons in the Interplanetary Medium Authors: Amata, E.; Domingo, V.; Page, D. E.; Wenzel, K. P. Bibcode: 1975ICRC....5.1761A Altcode: 1975ICRC...14.1761A The fluxes and anisotropies of low energy solar protons (less than 10 MeV) observed on two occasions when the HEOS-2 spacecraft encountered solar proton streams are studied taking into account the interplanetary magnetic field and plasma conditions existing at those times. (Plasma and magnetic field measurements are available from the same satellite). The variations in the streaming pattern are used to infer the topological structure of the interplanetary medium. The observed results are compared to existing models of particle propagation between the sun and the earth. Title: Das solare Ereignis vom 29. Oktober 1972: MeV Protonen, Alphateilchen und Elektronen Authors: Wenzel, K. -P.; Domingo, V.; Page, D. E. Bibcode: 1974MitAG..35..266W Altcode: No abstract at ADS Title: MeV Electrons, Protons and Alpha Particles Observed August 2-12 1972 Authors: Page, D. E.; Domingo, V.; Wenzel, K. -P. Bibcode: 1974ASSL...42..573P Altcode: 1974cimo.symp..573P An experiment was conducted on the ESRO satellite HEOS2 to monitor electrons, protons, and alpha-particles during specific solar particle events. Time constants of the decay and the anisotropies observed for different particle species were studied. Information was obtained concerning the interplanetary conditions. The conclusions derived from early particle data were in good agreement with more recent directly measured interplanetary data. Title: Energetic Electrons at the Magnetopause Authors: Domingo, V.; Page, D. E.; Wenzel, K. -P. Bibcode: 1974ASSL...42..159D Altcode: 1974cimo.symp..159D Results of observations of energetic and relativistic electrons made by the highly ecentric ESRO satellite HEOS 2 near the high-latitude tail magnetopause. There is generally a particle layer near the magnetopause, containing electrons up to about 1 MeV. The particle intensity shows a clear dependence on geomagnetic activity. Title: Measurements of Solar Protons in the Near Earth Magnetotail Authors: Domingo, V.; Page, D. E.; Wenzel, K. -P. Bibcode: 1974ASSL...42..507D Altcode: 1974cimo.symp..507D Preliminary results of the measurement of protons in the high latitude magnetosphere using the HEOS2 spin stabilized spacecraft. Data were obtained from the front solid state detector in anticoincidence with the back detector and the scintillator. The detector was operated on an angular mode while the channel measured protons of 1 to 9 MeV and electrons of about 0.4 to 0.6 MeV. Results indicated that the anisotropy measurement in the near earth magnetotail for protons of about 1 MeV showed a reasonable gradient of fluxes present in it. It is possible to use this measurement to map the penetration of protons into the polar cap. Title: Solar particle penetration through the magnetosheath Authors: Domingo, V.; Page, D. E.; Wenzel, K. -P. Bibcode: 1974stp.....2...96D Altcode: Data from HEOS-2 and from the NOAA experiment on Explorer 41 are presented which demonstrate that often the bow shock and magnetosheath seriously distort the flux of 1-MeV solar particles, so that it is no longer valid to assume that the magnetopause is the boundary between the interplanetary medium and the magnetotail. The change in absolute value and direction of the flux of particles that might be expected to occur at the magnetopause is not always seen exactly at that point. Rather, this change occurs sometimes further away in the magnetosheath, and sometimes the magnetopause looks completely transparent to arriving energetic particles as if the magnetotail were a continuation of the magnetosheath. Title: Magnetosheath observations at high northern latitudes by Heos 2 Authors: Hedgecock, P. C.; Cerulli, P.; Coletti, A.; Egidi, A.; Marconero, R.; Domingo, V.; Köhn, D.; Page, D. E.; Taylor, B. G.; Wenzel, K. -P. Bibcode: 1973JGR....78.1715H Altcode: No abstract at ADS Title: The April 17/18, 1972 Solar Event: Spectral and Directional Measurements of Protons, Alpha-Particles, and Electrons. (Abstract) Authors: Wenzel, K. -P.; Domingo, V.; Page, D. E.; Taylor, B. G. Bibcode: 1973ICRC....2.1438W Altcode: 1973ICRC...13.1438W No abstract at ADS Title: The April 17/18, 1972 Solar Event: Spectral and Directional Measurements of Protons, Alpha-Particles, and Electrons Authors: Wenzel, K. P.; Domingo, V.; Page, D. E.; Taylor, B. G. Bibcode: 1973ICRC....5.3151W Altcode: 1973ICRC...13.3151W No abstract at ADS Title: High energy electrons at the magnetopause above the north pole. Preliminary results from the HEOS 2 satellite. Authors: Page, D. E.; Domingo, V.; Köhn, D.; Taylor, B. G.; Wenzel, K. -P.; Hedgecock, P. C. Bibcode: 1973spre.conf..631P Altcode: 1973spre....2..631P No abstract at ADS Title: Northern Polar Cap Particle Flux Variations Following the 2 November 1969 Event Authors: Domingo, V.; Page, E. E.; Shaw, M. L. Bibcode: 1972spen.conf..105D Altcode: No abstract at ADS Title: New Results in Particle Arrival at the Polar Caps Authors: Page, D. E.; Domingo, V. Bibcode: 1972ASSL...32..107P Altcode: 1972emp..conf..107P No abstract at ADS Title: Two-satellite observation of spatial and temporal particle flux variations over the polar caps Authors: Domingo, V.; Page, D. E. Bibcode: 1972JGR....77.1971D Altcode: No abstract at ADS Title: North-South Asymmetry in Polar Cap Regions. (Abstract) Authors: Domingo, V.; Page, D. E. Bibcode: 1971ICRC....2..825D Altcode: 1971ICRC...12..825D No abstract at ADS Title: North-South Asymmetry in Polar Cap Regions Authors: Domingo, V.; Page, D. E. Bibcode: 1971ICRC....5.2009D Altcode: 1971ICRC...12.2009D No abstract at ADS Title: North-south asymmetry of solar-particle fluxes in polar-cap regions Authors: Domingo, V.; Page, D. E. Bibcode: 1971JGR....76.8159D Altcode: On January 24, 1969, an experiment on the Esro 1/Aurorae satellite recorded a flux over the central north pole that at times was a factor of 7 greater than that seen over the south pole. This asymmetry is discussed in relation to the interplanetary-field direction measured at the same time by the Heos spacecraft, and comparison is made with the opposite asymmetrical configuration observed by Evans and Stone (1969) on November 2, 1967. From the evidence of two events it would appear that a southward interplanetary field plays a significant role in permitting direct access, while the magnitude and polarity of the asymmetry are determined by, respectively, interplanetary-particle anisotropy and the ‘toward’ or ‘away’ nature of the field. Title: Muons in air showers of energies above 1017 eV Authors: Suga, K.; Shibata, S.; Mikamo, S.; Toyoda, Y.; Murakami, K.; Lapointe, M.; Kamata, K.; Domingo, V. Bibcode: 1970ICRC....3..423S Altcode: 1969ICRC....3..423S; 1970ICRC...11c.423S No abstract at ADS Title: Predominantly electromagnetic air showers of energy 1014 eV to 1016 eV Authors: Kamata, K.; Shibata, S.; Saavedra, O.; Domingo, V.; Suga, K.; Murakami, K.; Toyoda, Y.; Lapointe, M.; Gaebler, J.; Escobar, I. Bibcode: 1968CaJPS..46...72K Altcode: 1968CaJPh..46S..72K; 1968ICRC...10...72K No abstract at ADS Title: Note on the primary energy spectrum Authors: Lapointe, M.; Kamata, K.; Gaebler, J.; Escobar, I.; Domingo, V.; Suga, K.; Murakami, K.; Toyoda, Y.; Shibata, S. Bibcode: 1968CaJPS..46...68L Altcode: 1968ICRC...10...68L; 1968CaJPh..46S..68L No abstract at ADS Title: Studies of primary cosmic rays in the energy region 1014 to 1017 eV (Bolivian Air Shower Joint Experiment) Authors: Toyoda, Y.; Suga, K.; Murakami, K.; Hasegawa, H.; Shibata, S.; Domingo, V.; Escobar, I.; Kamata, K.; Bradt, H.; Clark, G.; La Pointe, M. Bibcode: 1965ICRC....2..708T Altcode: 1965ICRC....9..708T No abstract at ADS Title: The Primary energy spectrum from 8 x 1014-4 x 1017 eV Authors: Bradt, H.; Clark, G.; La Pointe, M.; Domingo, V.; Escobar, I.; Kamata, K.; Murakami, K.; Suga, K.; Toyoda, Y. Bibcode: 1965ICRC....2..715B Altcode: 1965ICRC....9..715B No abstract at ADS Title: Evidence for extensive air showers with extremely few penetrating particles Authors: Suga, K.; Escobar, I.; Murakami, K.; Domingo, V.; Toyoda, Y.; Clark, G.; La Pointe, M. Bibcode: 1963ICRC....4....9S Altcode: 1963ICRC....8d...9S No abstract at ADS Title: Primary energy spectrum from 6.1014 ev to 4.10 ev Authors: Clark, G.; Bradt, H.; La Pointe, M.; Domingo, V.; Escobar, I.; Murakami, K.; Suga, K.; Toyoda, Y.; Hersil, J. Bibcode: 1963ICRC....4...65C Altcode: 1963ICRC....8d..65C No abstract at ADS Title: Character of air showers at 5200 m altitude Authors: Escobar, I.; Domingo, V.; Murakami, K.; Suga, K.; Toyoda, Y.; Clark, G.; La Pointe, M.; Oda, M.; Bradt, H.; Miura, I.; Nagano, M.; Shibata, S.; Tanahashi, G.; Hasegawa, H. Bibcode: 1963ICRC....4..168E Altcode: 1963ICRC....8d.168E No abstract at ADS Title: A general account of the various research activities at Chacaltaya Authors: Domingo, V. Bibcode: 1963ICRC....4....3D Altcode: 1963ICRC....8d...3D No abstract at ADS