Author name code: anderson ADS astronomy entries on 2022-09-14 author:"Anderson, Lawrence S." ------------------------------------------------------------------------ Title: Self-absorption in [C II], 12CO, and H II in RCW120. Building up a geometrical and physical model of the region (Corrigendum) Authors: Kabanovic, S.; Schneider, N.; Ossenkopf-Okada, V.; Falasca, F.; Güsten, R.; Stutzki, J.; Simon, R.; Buchbender, C.; Anderson, L.; Bonne, L.; Guevara, C.; Higgins, R.; Koribalski, B.; Luisi, M.; Mertens, M.; Okada, Y.; Röllig, M.; Seifried, D.; Tiwari, M.; Wyrowski, F.; Zavagno, A.; Tielens, A. G. G. M. Bibcode: 2022A&A...660C...2K Altcode: No abstract at ADS Title: Self-absorption in [C II], 12CO, and H I in RCW120. Building up a geometrical and physical model of the region Authors: Kabanovic, S.; Schneider, N.; Ossenkopf-Okada, V.; Falasca, F.; Güsten, R.; Stutzki, J.; Simon, R.; Buchbender, C.; Anderson, L.; Bonne, L.; Guevara, C.; Higgins, R.; Koribalski, B.; Luisi, M.; Mertens, M.; Okada, Y.; Röllig, M.; Seifried, D.; Tiwari, M.; Wyrowski, F.; Zavagno, A.; Tielens, A. G. G. M. Bibcode: 2022A&A...659A..36K Altcode: 2021arXiv211211336K
Aims: Revealing the 3D dynamics of H II region bubbles and their associated molecular clouds and H I envelopes is important for developing an understanding of the longstanding problem as to how stellar feedback affects the density structure and kinematics of the different phases of the interstellar medium.
Methods: We employed observations of the H II region RCW 120 in the [C II] 158 μm line, observed within the Stratospheric Observatory for Infrared Astronomy (SOFIA) legacy program FEEDBACK, and in the 12CO and 13CO (3 →2) lines, obtained with the Atacama Pathfinder Experiment (APEX) to derive the physical properties of the gas in the photodissociation region (PDR) and in the molecular cloud. We used high angular resolution H I data from the Southern Galactic Plane Survey to quantify the physical properties of the cold atomic gas through H I self-absorption. The high spectral resolution of the heterodyne observations turns out to be essential in order to analyze the physical conditions, geometry, and overall structure of the sources. Two types of radiative transfer models were used to fit the observed [C II] and CO spectra. A line profile analysis with the 1D non-LTE radiative transfer code SimLine proves that the CO emission cannot stem from a spherically symmetric molecular cloud configuration. With a two-layer multicomponent model, we then quantified the amount of warm background and cold foreground gas. To fully exploit the spectral-spatial information in the CO spectra, a Gaussian mixture model was introduced that allows for grouping spectra into clusters with similar properties.
Results: The CO emission arises mostly from a limb-brightened, warm molecular ring, or more specifically a torus when extrapolated in 3D. There is a deficit of CO emission along the line-of-sight toward the center of the H II region which indicates that the H II region is associated with a flattened molecular cloud. Self-absorption in the CO line may hide signatures of infalling and expanding molecular gas. The [C II] emission arises from an expanding [C II] bubble and from the PDRs in the ring/torus. A significant part of [C II] emission is absorbed in a cool (~60-100 K), low-density (<500 cm−3) atomic foreground layer with a thickness of a few parsec.
Conclusions: We propose that the RCW 120 H II region formed in a flattened, filamentary, or sheet-like, molecular cloud and is now bursting out of its parental cloud. The compressed surrounding molecular layer formed a torus around the spherically expanding H II bubble. This scenario can possibly be generalized for other H II bubbles and would explain the observed "flat" structure of molecular clouds associated with H II bubbles. We suggest that the [C II] absorption observed in many star-forming regions is at least partly caused by low-density, cool, H I -envelopes surrounding the molecular clouds.

The 12CO and 13CO (3 →2) data shown in Fig. 4 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/659/A36

The [C II] data are provided at the NASA/IPAC Infrared science archive at https://irsa.ipac.caltech.edu/Missions/sofia.html Title: The SEDIGISM survey: The influence of spiral arms on the molecular gas distribution of the inner Milky Way Authors: Colombo, D.; Duarte-Cabral, A.; Pettitt, A. R.; Urquhart, J. S.; Wyrowski, F.; Csengeri, T.; Neralwar, K. R.; Schuller, F.; Menten, K. M.; Anderson, L.; Barnes, P.; Beuther, H.; Bronfman, L.; Eden, D.; Ginsburg, A.; Henning, T.; König, C.; Lee, M. -Y.; Mattern, M.; Medina, S.; Ragan, S. E.; Rigby, A. J.; Sánchez-Monge, Á.; Traficante, A.; Yang, A. Y.; Wienen, M. Bibcode: 2022A&A...658A..54C Altcode: 2021arXiv211006071C The morphology of the Milky Way is still a matter of debate. In order to shed light on uncertainties surrounding the structure of the Galaxy, in this paper, we study the imprint of spiral arms on the distribution and properties of its molecular gas. To do so, we take full advantage of the SEDIGISM (Structure, Excitation, and Dynamics of the Inner Galactic Interstellar Medium) survey that observed a large area of the inner Galaxy in the 13CO (2-1) line at an angular resolution of 28''. We analyse the influences of the spiral arms by considering the features of the molecular gas emission as a whole across the longitude-velocity map built from the full survey. Additionally, we examine the properties of the molecular clouds in the spiral arms compared to the properties of their counterparts in the inter-arm regions. Through flux and luminosity probability distribution functions, we find that the molecular gas emission associated with the spiral arms does not differ significantly from the emission between the arms. On average, spiral arms show masses per unit length of ~105-106 M kpc−1. This is similar to values inferred from data sets in which emission distributions were segmented into molecular clouds. By examining the cloud distribution across the Galactic plane, we infer that the molecular mass in the spiral arms is a factor of 1.5 higher than that of the inter-arm medium, similar to what is found for other spiral galaxies in the local Universe. We observe that only the distributions of cloud mass surface densities and aspect ratio in the spiral arms show significant differences compared to those of the inter-arm medium; other observed differences appear instead to be driven by a distance bias. By comparing our results with simulations and observations of nearby galaxies, we conclude that the measured quantities would classify the Milky Way as a flocculent spiral galaxy, rather than as a grand-design one.

Full Table 1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/658/A54 Title: VizieR Online Data Catalog: Self-absorption in RCW 120 (Kabanovic+, 2022) Authors: Kabanovic, S.; Schneider, N.; Ossenkopf-Okada, V.; Falasca, F.; Guesten, R.; Stutzki, J.; Simon, R.; Buchbender, C.; Anderson, L.; Bonne, L.; Guevara, C.; Higgins, R.; Koribalski, B.; Luisi, M.; Mertens, M.; Okada, Y.; Roellig, M.; Seifried, D.; Tiwari, M.; Wyrowski, F.; Zavagno, A.; Tielens, A. G. G. M. Bibcode: 2021yCat..36590036K Altcode: Spectral data cubes of 12CO (3-2) (at 345.796GHz) and 1 (at 330.588GHz),using the LAsMA array on APEX (Atacama Pathfinder Experiment) telescope. All spectra are calibrated in main beam brightness temperatures with a main-beam efficiency of 0.68 at 345.8GHz.

The observed spectra are convolved with a Gaussian function to 20'' resolution on a grid with a pixel size of 5''.

The spectra are resampled to a velocity resolution of 1 km/s.

(2 data files). Title: ePESSTO+ spectroscopic classification of optical transients Authors: Pessi, P. J.; Galbany, L.; Gromadzki, M.; Benetti, S.; Ihanec, N.; Paraskeva, E.; Chen, T. W.; Strotjohann, N. L.; Anderson; Bravo, T. M.; Inserra, C.; Kankare, E.; Nicholl, M.; Yaron, O.; Young, D.; Tonry, J.; Denneau, L.; Heinze, A.; Weiland, H.; Stalder, B.; Rest, A.; Smith, K. W.; Smartt, S. J.; Gillanders, J.; McBrien, O.; Srivastav, S. Bibcode: 2021TNSAN.209....1P Altcode: This report includes classifications of 8 Type Ia's, 2 Type Ic-BL's, 2 Type II's and a Tybe Ib, We encourage follow-up observations. Title: The SEDIGISM survey: First Data Release and overview of the Galactic structure Authors: Schuller, F.; Urquhart, J. S.; Csengeri, T.; Colombo, D.; Duarte-Cabral, A.; Mattern, M.; Ginsburg, A.; Pettitt, A. R.; Wyrowski, F.; Anderson, L.; Azagra, F.; Barnes, P.; Beltran, M.; Beuther, H.; Billington, S.; Bronfman, L.; Cesaroni, R.; Dobbs, C.; Eden, D.; Lee, M. -Y.; Medina, S. -N. X.; Menten, K. M.; Moore, T.; Montenegro-Montes, F. M.; Ragan, S.; Rigby, A.; Riener, M.; Russeil, D.; Schisano, E.; Sanchez-Monge, A.; Traficante, A.; Zavagno, A.; Agurto, C.; Bontemps, S.; Finger, R.; Giannetti, A.; Gonzalez, E.; Hernandez, A. K.; Henning, T.; Kainulainen, J.; Kauffmann, J.; Leurini, S.; Lopez, S.; Mac-Auliffe, F.; Mazumdar, P.; Molinari, S.; Motte, F.; Muller, E.; Nguyen-Luong, Q.; Parra, R.; Perez-Beaupuits, J. -P.; Schilke, P.; Schneider, N.; Suri, S.; Testi, L.; Torstensson, K.; Veena, V. S.; Venegas, P.; Wang, K.; Wienen, M. Bibcode: 2021MNRAS.500.3064S Altcode: 2020arXiv201201527S; 2020MNRAS.tmp.2600S; 2020MNRAS.500.3064S The SEDIGISM (Structure, Excitation and Dynamics of the Inner Galactic Interstellar Medium) survey used the APEX telescope to map 84 deg2 of the Galactic plane between ℓ = -60° and +31° in several molecular transitions, including 13CO (2 - 1) and C18O (2 - 1), thus probing the moderately dense (∼103 cm-3) component of the interstellar medium. With an angular resolution of 30 arcsec and a typical 1σ sensitivity of 0.8-1.0 K at 0.25 km s-1 velocity resolution, it gives access to a wide range of structures, from individual star-forming clumps to giant molecular clouds and complexes. The coverage includes a good fraction of the first and fourth Galactic quadrants, allowing us to constrain the large-scale distribution of cold molecular gas in the inner Galaxy. In this paper, we provide an updated overview of the full survey and the data reduction procedures used. We also assess the quality of these data and describe the data products that are being made publicly available as part of this First Data Release (DR1). We present integrated maps and position-velocity maps of the molecular gas and use these to investigate the correlation between the molecular gas and the large-scale structural features of the Milky Way such as the spiral arms, Galactic bar and Galactic Centre. We find that approximately 60 per cent of the molecular gas is associated with the spiral arms and these appear as strong intensity peaks in the derived Galactocentric distribution. We also find strong peaks in intensity at specific longitudes that correspond to the Galactic Centre and well-known star-forming complexes, revealing that the 13CO emission is concentrated in a small number of complexes rather than evenly distributed along spiral arms. Title: Stellar feedback and triggered star formation in the prototypical bubble RCW 120 Authors: Luisi, M.; Anderson, L.; Schneider, N.; Simon, R.; Kabanovic, S.; Guesten, R.; Zavagno, A.; Broos, P.; Buchbender, C.; Guevara, C.; Jacobs, K.; Justen, M.; Klein, B.; Linville, D.; Roellig, M.; Russeil, D.; Stutzki, J.; Tiwari, M.; Townsley, L.; Tielens, A. Bibcode: 2021AAS...23713704L Altcode: Radiative and mechanical feedback of massive stars regulates star formation and galaxy evolution. Positive feedback triggers the creation of new stars by collecting dense shells of gas, while negative feedback disrupts star formation by shredding molecular clouds. Although key to understanding star formation, their relative importance is unknown. Here we report velocity-resolved observations from the SOFIA legacy program FEEDBACK of the massive star-forming region RCW 120 in the [CII] 1.9 THz fine-structure line, revealing a gas shell expanding at 15 km/s. Complementary APEX CO J=3-2 345 GHz observations exhibit a ring-structure of molecular gas, fragmented into clumps that are actively forming stars. Our observations demonstrate that triggered star formation can occur on much shorter timescales than hitherto thought (<0.15 Myr), suggesting that positive feedback operates on short time periods. Title: Stellar feedback and triggered star formation in the prototypical bubble RCW 120 Authors: Luisi, M.; Anderson, L.; Schneider, N.; Simon, R.; Kabanovic, S.; Guesten, R.; Zavagno, A.; Broos, P.; Buchbender, C.; Guevara, C.; Jacobs, K.; Justen, M.; Klein, B.; Linville, D.; Roellig, M.; Russeil, D.; Stutzki, J.; Tiwari, M.; Townsley, L.; Tielens, A. Bibcode: 2021AAS...23711403L Altcode: Radiative and mechanical feedback of massive stars regulates star formation and galaxy evolution. Positive feedback triggers the creation of new stars by collecting dense shells of gas, while negative feedback disrupts star formation by shredding molecular clouds. Although key to understanding star formation, their relative importance is unknown. Here we report velocity-resolved observations from the SOFIA legacy program FEEDBACK of the massive star-forming region RCW 120 in the [CII] 1.9 THz fine-structure line, revealing a gas shell expanding at 15 km/s. Complementary APEX CO J=3-2 345 GHz observations exhibit a ring-structure of molecular gas, fragmented into clumps that are actively forming stars. Our observations demonstrate that triggered star formation can occur on much shorter timescales than hitherto thought (<0.15 Myr), suggesting that positive feedback operates on short time periods. Title: Modeling Chemical Abundance Evolution in Dwarf Galaxies Authors: Kwon, A. Y.; Anderson, L.; Kumar, S. Bibcode: 2021AAS...23714702K Altcode: The abundance of elements within a galaxy can give a strong insight into the physical processes that have occurred within the galaxy. Thus, an important part of understanding galaxy evolution relies on knowing how the chemical abundance in a galaxy has changed over time. However, there is no way to retroactively observe the evolving chemical composition of a galaxy, which is why we turn to the present day metallicities of stars. Since stars were formed from the materials within the galaxy, the metallicity of each star is somewhat representative of the metallicity of the entire galaxy at the time the star was formed. Using the observed metallicities of stars within a galaxy and the measured star formation rate of the galaxy our model infers parameters within the Chempy chemical evolution model (Rybizki et al. 2017) to find not only the most likely chemical abundances over time but also other important characteristics of the galaxy including the outflow feedback fraction and SN1a time delay. When applied to a simulated FIRE dwarf galaxy, our model was able to closely predict the galaxy's chemical evolution, verifying the accuracy of our model. In the future, we will apply the model to the Sculptor dwarf galaxy and add in a metallicity variance parameter to better understand the spread of elements within the galaxy. Overall, our model can serve as a powerful tool in improving both the predicted metallicity evolution and inferred galactic parameters of real dwarf galaxies. Title: Detecting HII Regions in the Outer Scutum-Centaurus Arm Authors: Johnson, A.; Armentrout, W.; Anderson, L.; Bania, T.; Balser, D.; Wenger, T. Bibcode: 2021AAS...23715310J Altcode: There is relatively little known about Galactic star formation in the outer edges of the Milky Way, particularly in the Outer Scutum-Centaurus spiral arm (OSC). Lying about 15 kpc from the center of the Galaxy, the OSC was discovered in 2011 and is the most distant molecular spiral arm of the Milky Way. The OSC warps up to 4 degrees above the Galactic plane and as a result, has been excluded from the scope of many surveys of the Galactic plane, typically confined to a single degree above or below the plane. The goal of our study is to identify radio continuum from HII regions in the OSC in order to better understand the population of high-mass star formation regions in the outer Galaxy. We observed 12 HII Regions in the OSC using the Very Large Array at 10 GHz. Of our 12 targets, 7 are re-observations of undetected sources from Armentrout et al. (2017). The remaining 5 targets are sources without previously observed 10 GHz radio continuum data. We identify 10 GHz radio continuum associated with 7 of our OSC HII region targets for the first time. Assuming one dominant ionizing source per HII region, we assign spectral types from O9 to O5.5 for these sources, depending on their distance and continuum intensity. The remaining 5 nondetections represent lower-mass (B-type) star-forming regions below the sensitivity limit of our survey. These regions represent very high-mass star formation on the outer edge of the Galaxy, where densities and metallicities might be more similar to that of a much younger Milky Way or lower mass galaxies like the Magellanic Clouds. Title: Oxygen Isotopes in Tree Cellulose Reveal Ecohydrological Relationships in the Colorado Rocky Mountains Authors: Brice, B.; Anderson, L.; Berkelhammer, M. B.; Mast, A. Bibcode: 2020AGUFMPP006..02B Altcode: Oxygen isotopes in xylem water or cellulose can be useful as an indicator of the moisture sources for trees in modern and paleo contexts. In the snow-dominated high elevations of the Rocky Mountains, the oxygen isotope ratio in the cellulose of conifer trees may provide valuable information about the seasonal origins of tree water use, which can be key to understanding how snowpack or summer rains have varied through time and how this has affected tree growth. In this pilot study, annual and sub-annual tree-ring cellulose isotopic measurements from Picea engelmannii were compared with monthly meteoric oxygen isotope measurements, precipitation amount (P) and temperature (T) data to investigate the climate-proxy response and to refine the use of wood cellulose oxygen isotopes as a hydroclimate proxy. Preliminary results indicate that annual-ring cellulose generally coincides with year-to-year variation of volume-weighted meteoric (p-weight) oxygen isotopes between the years 2007-2016. The relationship among cellulose oxygen isotopes, p-weight oxygen isotopes, and temperature is more pronounced for the annual growing season average (May-Sep). Sub-annual tree-ring increments indicate inter-annual differences between cellulose oxygen isotope values and the timing of p-weight oxygen isotopes, which may indicated tree-level discrimination between cool-season and growing season source water depending on environmental conditions for that year. The statistical relationship between sub-annual cellulose oxygen isotopes and the climate variables (P and T) suggests that T is an important control on tree-ring growth in May through August. May and July P corresponds to the early portion of the growth ring, while August P corresponds to late season growth. Our results indicate that there is a connection between seasonal climate and oxygen isotope values derived from tree-ring cellulose in high-elevation, snow-dominated systems. An improved understanding of this relationship will assist in proxy-refinement and contribute to robust future reconstructions of hydroclimate. Title: A Reconstruction of Southcentral Alaska Late Holocene Hydroclimate from Peatland Cellulose Oxygen Isotopes Authors: Nash, B. C.; Jones, M.; Berkelhammer, M. B.; Anderson, L. Bibcode: 2020AGUFMPP0030003N Altcode: The use of peat cellulose oxygen isotopes as a proxy for hydroclimate has commonly been applied to a single species in Sphagnum-dominated bogs; however, recent advances in the application of this proxy to wetlands with diverse species, such as fens, broadens the scope of their utility. Here we present a late-Holocene record of species-specific cellulose oxygen isotopes (δ18Ocellulose) from a 7-m peat core collected from a fen located on the Kenai Peninsula in Southcentral Alaska. Plant macrofossils were categorized (herbaceous, bryophytic, ligneous) and tallied (e.g., seeds, leaves) for the size fraction >250 µm, and select specimens were picked for 14C dating to generate a chronology in conjunction with 210Pb. Oxygen isotopic analysis was performed on alpha cellulose extracted from moss (Sphagnum and brown mosses) and sedge (Carex spp.) macrofossils that were separated prior to cellulose extraction to account for unique fractionation factors resulting from differences in plant physiology. Previous analyses revealed that the moss δ18Ocellulose values were ~2 ‰ lighter on average than sedge at the same site. Fen surface water δ18O values fall on the global meteoric water line, indicating they accurately reflect precipitation. The average isotopic difference between modern plant cellulose and peatland water (Δδ18Ocellulose-water) is 33.9 ± 1.2 ‰. Lacustrine sediments with aquatic macrofossils (Chara oospores, Daphnia ephippia, and chironomids) comprise the lower half of the core, indicating a shallow pond persisted from ~10 ka to ~6 ka, when the pond terrestrialized to a peatland. Between ~6 to 4 ka, sedge macrofossils dominated, followed by a period when the system fluctuated between sedge and Sphagnum, before transitioning back to sedge by ~2 ka. An abrupt transition to Sphagnum peat occurred in the last several decades and persists to present. The δ18Ocellulose values during the past 3 kyr range from ~17 ‰ to ~21.5 ‰, with higher values at the core top. The inferred bog water values between -12.5 ‰ and -17 ‰ are consistent with modern precipitation values and indicate that this record can be placed into the context of regional synoptic-scale hydroclimate changes throughout the late-Holocene, including variability in the strength and position of the Aleutian Low. Title: VizieR Online Data Catalog: Stellar parameters for 13196 Kepler dwarfs (Angus+, 2020) Authors: Angus, R.; Beane, A.; Price-Whelan, A. M.; Newton, E.; Curtis, J. L.; Berger, T.; van Saders, J.; Kiman, R.; Foreman-Mackey, D.; Lu, Y.; Anderson, L.; Faherty, J. K. Bibcode: 2020yCat..51600090A Altcode: We used the publicly available Kepler-Gaia DR2 crossmatched catalog to combine the McQuillan+ (2014, J/ApJS/211/24) catalog of stellar rotation periods, measured from Kepler light curves, with the Gaia DR2 catalog of parallaxes, proper motions, and apparent magnitudes.

(1 data file). Title: High-Mass Star Formation in the Far Outer Galaxy Authors: Armentrout, W.; Anderson, L.; Frayer, D.; Balser, D.; Bania, T.; Dame, T.; Wenger, T. Bibcode: 2020AAS...23620906A Altcode: HII regions are the archetypical tracers of high-mass star formation. Because of their high luminosities, they can be seen across the entire Galactic disk from mid-infrared to radio wavelengths. A uniformly sensitive survey of Galactic HII regions across the disk would allow us to constrain the properties of Galactic structure and star formation. We have cataloged over 8000 HII regions and candidates in the WISE Catalog of Galactic HII Regions (astro.phys.wvu.edu/wise), but only 2000 of these are confirmed HII regions. The work is ongoing, but from our survey completeness limits and population synthesis modeling, we predict there are nearly 10,000 HII regions in the Milky Way created by a central star of type B2 or earlier. A population of especially interesting HII regions trace the Outer Scutum-Centaurus spiral arm (OSC), the most distant molecular spiral arm in the Milky Way. These regions represent star formation at low densities and low metallicities, similar to the conditions in galaxies like the Large Magellanic Cloud or a much younger Milky Way. To date, we have detected high-mass star formation at 17 locations in the OSC, with the most distant source at 23.5 kpc from the Sun and 17 kpc from the Galactic Center. They have molecular cloud masses up to 105 Msol and central stellar types as early as O4. By comparing molecular and stellar masses, we can begin to put constraints on the star formation efficiency of these distant outer Galaxy sources. We map the ionized gas using the Very Large Array at X-band in the D-configuration. We map the 13CO, HCN, and HCO+ molecular gas emission using the Argus array on the Green Bank Telescope, producing individual 5 arcmin maps with 8 arcsec resolution and 0.5 K sensitivity in 20 minutes. Title: Unusual Galactic HII Regions at the Intersection of the Central Molecular Zone and the Far Dust Lane Authors: Anderson, L. Bibcode: 2020AAS...23621301A Altcode: Sgr E is a star formation complex found toward the Galactic center that consists of numerous discrete, compact HII regions. It is located at the intersection between the Central Molecular Zone (CMZ) and the far dust lane of the Galactic bar, similar to "hot spots" seen in external Galaxies. Sgr E is unusual in that: 1) the individual Sgr E HII regions all share similar radio luminosities and angular extents; 2) it has the largest absolute radial velocity of any known Galactic HII region; and 3) the individual Sgr E HII regions are deficient in ∼10μm emission from polycyclic aromatic hydrocarbons. Green Bank Telescope (GBT) radio recombination line observations allowed us to increase the known membership of Sgr E to 20 HII regions, although the many mid-infrared sources in the area indicates that there may be as many as 100 HII regions in Sgr E. Using APEX SEDIGISM 13CO 3-2 data, we discover a 3.0×105 Solar mass molecular cloud associated with Sgr E, but find no molecular or far-infrared concentrations at the locations of the Sgr E HII regions. Far-infrared data and new GBT NH3 observations both show that the dust and gas have elevated temperatures relative to the dust and gas temperatures of other known HII regions. Comparison with simulations indicates that the Sgr E HII regions formed in the dust lane of the Galactic bar a couple Myr ago and will overshoot the CMZ, crashing into the near dust lane. We propose that the PDRs of the Sgr E HII regions were stripped during its orbit about that Galactic center. Title: The Galactic HII Region Luminosity Function at Radio and Infrared Wavelengths Authors: Mascoop, J.; Anderson, L.; Makai, Z.; Armentrout, W.; Balser, D.; Wenger, T.; Bania, T. Bibcode: 2020AAS...23633303M Altcode: We determine the form of the Galactic HII region luminosity function (LF) at multiple infrared and radio frequencies. The HII region LF has been extensively studied in external galaxies, but has not received as much attention in the Milky Way. Investigations of the Galactic HII region LF have historically been limited by small sample sizes and incompleteness at lower luminosities. We find that our sample of 797 first Galactic quadrant HII regions is complete for all HII regions ionized by single O9.5 stars, and therefore provides an excellent dataset to use for extragalactic comparisons. The data are best fit by a single power law with an index of -1.73. There is little variation in the power law index with frequency. We find agreement between our result and previous studies in Hα, and therefore expect that future LF studies at wavelengths less affected by extinction should find similar results to those done in Hα. Many extragalactic LF studies suggest that a more general form of the HII region LF is a double power law. Such a form may reflect two physically distinct subpopulations; previous studies suggest the break in the double power law occurs at the transition between ionization- and density-bounded regions or regions ionized by single and multiple stars. We find that the Galactic LF is best fit by a single power law, even when it is divided into subsets by heliocentric distance, Galactocentric radius, angular size, and location relative to the spiral arms. Title: GDIGS and the Distribution of Diffuse Ionized Gas in the Milky Way Authors: Linville, D. J.; Anderson, L.; Luisi, M. Bibcode: 2020AAS...23633302L Altcode: We present results from the Green Bank Telescope (GBT) Diffuse Ionized Gas Survey (GDIGS), which traces ionized gas in the inner Galactic plane by measuring radio recombination line (RRL) emission between 4 and 8 GHz. The survey covers the area within 0.5 degrees of the Galactic plane, from Galactic longitudes 32.3 degrees to -5 degrees, but there are extensions above and below the plane in select fields and extra coverage around W47 and W49. We automatically Gaussian-decomposed the GDIGS Hydrogen RRL emission, and furthermore separate the emission of diffuse ionized gas (DIG) from that of HII regions. The height of the Gaussian serves as an indicator of emission measure, while the full width at half maximum reflects temperature. Our decompositions therefore allow us to explore how these properties vary with Galactocentric radius, Galactic latitude, and Galactic longitude. The velocities obtained from the decompositions also allow us to construct longitude-velocity diagrams, which are informative of the structure of the Milky Way and its spiral arms. Title: A VLA Census of the Galactic HII Region Population Authors: Armentrout, W.; Anderson, L.; Wenger, T.; Balser, D.; Bania, T. Bibcode: 2020AAS...23523603A Altcode: The Milky Way contains a significant number of unconfirmed HII regions, the archetypical tracers of Galactic high-mass star formation. There are over 2000 confirmed HII regions in the Milky Way, but our Milky Way surveys are deficient by several thousand HII regions when compared to external galaxies with similar star formation rates. This is odd given our close proximity to these Milky Way HII regions compared to distant extragalactic sources. Through sensitive 9 GHz radio continuum observations with the Jansky Very Large Array, we explore a faint class of unconfirmed HII region candidates to put limits on the total population of Galactic HII regions. We show that stars of spectral type B2 create HII regions with similar infrared and radio continuum morphologies as those HII regions created by O-stars. We achieve this by measuring the peak and integrated radio flux densities from these faint infrared-identified objects and comparing the inferred Lyman continuum fluxes with spectral models of OB-stars. From our 50% detection rate of previously "radio quiet" sources from the WISE Catalog of Galactic HII regions, we expect a lower limit of ~7000 HII regions in our Galaxy. We have not yet discovered the vast majority of the Milky Way's HII regions. Title: A Beam-Forming Receiver for the GBT at 23 GHz Authors: Skipper, J.; Morgan, L.; Bandura, K.; Di Francesco, J.; Lockman, J.; Armentrout, W.; Frayer, D.; Jensen, L.; O'Neil, K.; White, S.; Anderson, L.; Araya, E. D.; Cazzoli, S.; Rosolowsky, E.; Sadavoy, S.; Sahlen, M.; Tobin, J. Bibcode: 2020AAS...23545104S Altcode: We are investigating the proposal to support the design, construction and commissioning of a K-band (18-26 GHz) 256 element phased array feed (PAF) receiver and associated beam-former capable of forming 225 independent beams (i.e. a 225 pixel spectroscopic camera), for the 100m diameter Green Bank Telescope (GBT). The proposed receiver will simultaneously observe the (1,1), (2,2), and (3,3) inversion transitions of ammonia, a critically important probe of dense molecular gas that can trace kinetic temperatures, optical depth and column densities simultaneously with minimal bias. There are other molecular tracers of star formation activity observable at this frequency band, including CCS and HC7N, which act as 'chemical clocks' and thus can distinguish between different modes of star formation (e.g. Seo et al., 2019). Water masers are also strong emitters in the range of the proposed receiver, tracing shocked gas and outflow motions in low- and high-mass star-forming regions (see Walsh et al., 2011) in addition to providing distance measurements to nearby active galaxies, yielding a direct measurement of the Hubble constant, independent of standard candles (Braatz et al., 2019). Furthermore, several radio recombination lines, including hydrogen and carbon transitions between 63α and 70α, will be observable, which will allow comprehensive studies of ionized gas and photon-dominated regions in star-forming regions and planetary nebulae.The GBT presents a 100m unblocked active surface, providing a combination of higher gain, higher sensitivity and better angular resolution at K-band than any other radio telescope. In comparison, interferometers such as the Very Large Array (VLA) offer higher angular resolution but simply do not have the sensitivity to large scales needed to detect extended emission from dense clumps within molecular clouds. The ∼32" angular resolution of the GBT at 23.7 GHz is well-matched to star-forming substructures in nearby clouds (0.07 pc at 450 pc, the distance of Orion) and the field-of-view of the instrument will surpass that of the 2' primary beam of the VLA. This will provide excellent short-spacing data for combination with interferometric observations, as well as make large area mapping more efficient. Title: Modeling Color-Magnitude Diagrams with Bayesian Neural Flows Authors: Cranmer, M.; Galvez, R.; Anderson, L.; Spergel, D.; Ho, S. Bibcode: 2020AAS...23538609C Altcode: We demonstrate an algorithm for learning a flexible Color-Magnitude Diagram (CMD) from noisy parallax and photometric measurements using a normalizing flow, a deep neural network capable of learning an arbitrary multi-dimensional probability distribution. Dust estimation and dereddening is done iteratively inside the model and without prior distance information, using the Bayestar map. Using this model, we can improve Gaia distance estimates and also learn CMDs specific to a particular stellar population. We conclude with a discussion of future work, which exploits the normalizing flow architecture to allow us to exactly marginalize over missing photometry, enabling the inclusion of many surveys without losing coverage. Title: CubeSat active thermal management in support of cooled electro-optical instrumentation for advanced atmospheric observing missions Authors: Anderson, L.; Swenson, C.; Davidson, R.; Mastropietro, A. J.; Maghsoudi, E.; Luong, S.; Cappucci, S.; Mckinley, I. Bibcode: 2018SPIE10769E..07A Altcode: The need for advanced cooled electro-optical instrumentation in remote observations of the atmosphere is well known and demonstrated by SABER on the TIMED mission. The relatively new use of small satellites in remote earth observing missions as, well as the challenges, are epitomized by the upcoming NOAA EON-IR 12U CubeSat missions. These advanced CubeSat missions, which hope to accomplish scientific objectives on the same scale as larger more traditional satellites, require advanced miniaturized cryocoolers and active methods for thermal management and power control. The active CryoCubeSat project (ACCS) is a demonstration of such a technology. Utilizing Ultrasonic Additive Manufacturing (UAM) techniques, a Mechanical Pumped Fluid Loop (MPFL), and miniature pumps and cryocoolers to create a closed loop fluid-based heat interchange system. The ACCS project creates a two-stage thermal control system targeting 6U CubeSat platforms. The first stage is composed of a miniature Ricor K508N cryocooler while the second is formed by a UAM fabricated heat exchanger MPFL system powered by a micro TCS M510 pump. The working fluid is exchanged between a built-in chassis heat exchanger and a deployable tracking radiator. This work details the theory design and testing of a relevant ground-based prototype and the analysis and modeling of the results as well as the development of a design tool to help in customized active thermal control designs for small satellites. Ultimately, the ACCS project hopes to enable a new generation of advanced CubeSat atmospheric observing missions. Title: The Romulus cosmological simulations: a physical approach to the formation, dynamics and accretion models of SMBHs Authors: Tremmel, M.; Karcher, M.; Governato, F.; Volonteri, M.; Quinn, T. R.; Pontzen, A.; Anderson, L.; Bellovary, J. Bibcode: 2017MNRAS.470.1121T Altcode: 2016arXiv160702151T We present a novel implementation of supermassive black hole (SMBH) formation, dynamics and accretion in the massively parallel tree+SPH code, ChaNGa. This approach improves the modelling of SMBHs in fully cosmological simulations, allowing for a more detailed analysis of SMBH-galaxy co-evolution throughout cosmic time. Our scheme includes novel, physically motivated models for SMBH formation, dynamics and sinking timescales within galaxies and SMBH accretion of rotationally supported gas. The sub-grid parameters that regulate star formation (SF) and feedback from SMBHs and SNe are optimized against a comprehensive set of z = 0 galaxy scaling relations using a novel, multidimensional parameter search. We have incorporated our new SMBH implementation and parameter optimization into a new set of high-resolution, large-scale cosmological simulations called Romulus. We present initial results from our flagship simulation, Romulus25, showing that our SMBH model results in SF efficiency, SMBH masses and global SF and SMBH accretion histories at high redshift that are consistent with observations. We discuss the importance of SMBH physics in shaping the evolution of massive galaxies and show how SMBH feedback is much more effective at regulating SF compared to SNe feedback in this regime. Further, we show how each aspect of our SMBH model impacts this evolution compared to more common approaches. Finally, we present a science application of this scheme studying the properties and time evolution of an example dual active galactic nucleus system, highlighting how our approach allows simulations to better study galaxy interactions and SMBH mergers in the context of galaxy-BH co-evolution. Title: High sensitivity of gross primary production in the Rocky Mountains to summer rain Authors: Berkelhammer, M.; Stefanescu, I. C.; Joiner, J.; Anderson, L. Bibcode: 2017GeoRL..44.3643B Altcode: In the catchments of the Rocky Mountains, peak snowpack is declining in response to warmer spring temperatures. To understand how this will influence terrestrial gross primary production (GPP), we compared precipitation data across the intermountain west with satellite retrievals of solar-induced fluorescence (SIF), a proxy for GPP. Annual precipitation patterns explained most of the spatial and temporal variability of SIF, but the slope of the response was dependent on site to site differences in the proportion of snowpack to summer rain. We separated the response of SIF to different seasonal precipitation amounts and found that SIF was approximately twice as sensitive to variations in summer rain than snowpack. The response of peak GPP to a secular decline in snowpack will likely be subtle, whereas a change in summer rain amount will have precipitous effects on GPP. The study suggests that the rain use efficiency of Rocky Mountain ecosystems is strongly dependent on precipitation form and timing. Title: Nickel Distribution Between Immiscible Melts as a Means to Understand the Influence of Ferric Iron on NiO Activity Coefficients Authors: Colson, R. O.; Young, E.; Anderson, L. Bibcode: 2017LPI....48.1548C Altcode: Distribution of NiO between two immiscible melts, NiO activity coefficient, and the effects of ferric iron. Title: Artview: Artview Release 1.2.3 Authors: Nick; Anderson; Lang, Timothy; Helmus, Jonathan J.; your git settings!, Check; Nesbitt, Steve Bibcode: 2016zndo.....47224N Altcode: We are happy to announce the release of ARTview v1.2! Highlights Restructing of Menu for easier use Introduction of modes - predefined configurations that can be changed at run time Reconfigure ```SelectRegion``` module Add new components: ```FileNavigator``` and ```PointsDisplay``` Add new plugins: ```DirectoryList```, ```ManualFilter```, ```ManualUnfold```, ```AccessTerminal``` (Py-ART 1.6 compatilbility) Add support for new-style and legacy grids (Py-ART 1.6) Ability to use Py-ART configuration file for defining colormaps Rename and redesign ```LinkPlugins``` to ```LinkSharedVariables`` Create conda package for easier installation (thanks Jonathan Helmus) Drop official support for Python 2.6 Add video Tutorials for help Title: Detection of two power-law tails in the probability distribution functions of massive GMCs. Authors: Schneider, N.; Bontemps, S.; Girichidis, P.; Rayner, T.; Motte, F.; André, P.; Russeil, D.; Abergel, A.; Anderson, L.; Arzoumanian, D.; Benedettini, M.; Csengeri, T.; Didelon, P.; di, Francesco J.; Griffin, M.; Hill, T.; Klessen, R. S.; Ossenkopf, V.; Pezzuto, S.; Rivera-Ingraham, A.; Spinoglio, L.; Tremblin, P.; Zavagno, A. Bibcode: 2015MNRAS.453L..41S Altcode: 2015arXiv150708869S We report the novel detection of complex high column density tails in the probability distribution functions (PDFs) for three high-mass star-forming regions (CepOB3, MonR2, NGC 6334), obtained from dust emission observed with Herschel. The low column density range can be fitted with a lognormal distribution. A first power-law tail starts above an extinction (AV) of ∼6-14. It has a slope of α 1.3-2 for the &ρ ≈ r-α profile for an equivalent density distribution (spherical or cylindrical geometry), and is thus consistent with free-fall gravitational collapse. Above AV ∼40, 60, and 140, we detect an excess that can be fitted by a flatter power-law tail with α > 2. It correlates with the central regions of the cloud (ridges/hubs) of size ∼;1 pc and densities above 104 cm-3. This excess may be caused by physical processes that slow down collapse and reduce the flow of mass towards higher densities. Possible are: (1) rotation, which introduces an angular momentum barrier, (2) increasing optical depth and weaker cooling, (3) magnetic fields, (4) geometrical effects, and (5) protostellar feedback. The excess/second power-law tail is closely linked to high-mass star-formation though it does not imply a universal column density threshold for the formation of (high-mass) stars. Title: All about baryons: revisiting SIDM predictions at small halo masses Authors: Fry, A. Bastidas; Governato, F.; Pontzen, A.; Quinn, T.; Tremmel, M.; Anderson, L.; Menon, H.; Brooks, A. M.; Wadsley, J. Bibcode: 2015MNRAS.452.1468F Altcode: 2015arXiv150100497B We use cosmological hydrodynamic simulations to consistently compare the assembly of dwarf galaxies in both Λ dominated, cold dark matter (CDM) and self-interacting dark matter (SIDM) models. The SIDM model adopts a constant cross-section of 2 cm2 g-1, a relatively large value to maximize its effects. These are the first SIDM simulations that are combined with a description of stellar feedback that naturally drives potential fluctuations able to create dark matter (DM) cores. Remarkably, SIDM fails to significantly lower the central DM density within the central 500 pc at halo peak velocities Vmax < 30 km s-1. This is due to the fact that the central regions of very low mass field haloes have relatively low central velocity dispersion and densities, leading to time-scales for SIDM collisions greater than a Hubble time. CDM haloes with Vmax < 30 km s-1 have inefficient star formation, and hence weak supernova feedback. At a fixed 2 cm2 g-1 SIDM cross-section, the DM content of very low mass CDM and SIDM haloes differs by no more than a factor of 2 within 100-200 pc. At larger halo masses (∼1010 M), the introduction of baryonic processes creates field dwarf galaxies with DM cores and central DM+baryon distributions that are effectively indistinguishable between CDM and SIDM. Both models are in broad agreement with observed Local Group field galaxies across the range of masses explored. To significantly differentiate SIDM from CDM at the scale of faint dwarf galaxies, a velocity-dependent cross-section that rapidly increases to values larger than 2 cm2 g-1 for haloes with Vmax < 25-30 km s-1 needs to be introduced. Title: Modeling NiO Activities in Silicate Melts Considering Separate Contributions from Ni2+ and O2-: Dependence of O2- on Melt Polymerization Authors: Anderson, L.; Young, E.; Colson, R. O. Bibcode: 2015LPI....46.1358A Altcode: 2015LPICo1832.1358A We propose a model for trace element oxide activities successful for NiO. The activity of the oxide ion varies according to the polymerization of the melt. Title: Worldwide Weather Radar Imagery May Allow Substantial Increase in Meteorite Fall Recovery Authors: Fries, M.; Matson, R.; Schaefer, J.; Fries, J.; Anderson, L. Bibcode: 2014LPICo1800.5443F Altcode: Radars everywhere / Watching stones fall overseas / There's more than you think. Title: SIGGMA: A Survey of Ionized Gas in the Galaxy, Made with the Arecibo Telescope Authors: Liu, B.; McIntyre, T.; Terzian, Y.; Minchin, R.; Anderson, L.; Churchwell, E.; Lebron, M.; Anish Roshi, D. Bibcode: 2013AJ....146...80L Altcode: 2013arXiv1308.3122L A Survey of Ionized Gas in the Galaxy, made with the Arecibo telescope (SIGGMA), uses the Arecibo L-band Feed Array (ALFA) to fully sample the Galactic plane (30° <= l <= 75° and -2° <= b <= 2° 175° <= l <= 207° and -2° <= b <= 1°) observable with the telescope in radio recombination lines (RRLs). Processed data sets are being produced in the form of data cubes of 2° (along l) × 4° (along b) × 151 (number of channels), archived and made public. The 151 channels cover a velocity range of 600 km s-1 and the velocity resolution of the survey changes from 4.2 km s-1 to 5.1 km s-1 from the lowest frequency channel to the highest frequency channel. RRL maps with 3.'4 resolution and a line flux density sensitivity of ~0.5 mJy will enable us to identify new H II regions, measure their electron temperatures, study the physics of photodissociation regions with carbon RRLs, and investigate the origin of the extended low-density medium. Twelve Hnα lines fall within the 300 MHz bandpass of ALFA; they are resampled to a common velocity resolution to improve the signal-to-noise ratio (S/N) by a factor of three or more and preserve the line width. SIGGMA will produce the most sensitive fully sampled RRL survey to date. Here, we discuss the observing and data reduction techniques in detail. A test observation toward the H II region complex S255/S257 has detected Hnα and Cnα lines with S/N > 10. Title: Model based systems engineering (MBSE) applied to Radio Aurora Explorer (RAX) CubeSat mission operational scenarios Authors: Spangelo, S. C.; Cutler, J.; Anderson, L.; Fosse, E.; Cheng, L.; Yntema, R.; Bajaj, M.; Delp, C.; Cole, B.; Soremekum, G.; Kaslow, D. Bibcode: 2013aero.confE..81S Altcode: Small satellites are more highly resource-constrained by mass, power, volume, delivery timelines, and financial cost relative to their larger counterparts. Small satellites are operationally challenging because subsystem functions are coupled and constrained by the limited available commodities (e.g. data, energy, and access times to ground resources). Furthermore, additional operational complexities arise because small satellite components are physically integrated, which may yield thermal or radio frequency interference. In this paper, we extend our initial Model Based Systems Engineering (MBSE) framework developed for a small satellite mission by demonstrating the ability to model different behaviors and scenarios. We integrate several simulation tools to execute SysML-based behavior models, including subsystem functions and internal states of the spacecraft. We demonstrate utility of this approach to drive the system analysis and design process. We demonstrate applicability of the simulation environment to capture realistic satellite operational scenarios, which include energy collection, the data acquisition, and downloading to ground stations. The integrated modeling environment enables users to extract feasibility, performance, and robustness metrics. This enables visualization of both the physical states (e.g. position, attitude) and functional states (e.g. operating points of various subsystems) of the satellite for representative mission scenarios. The modeling approach presented in this paper offers satellite designers and operators the opportunity to assess the feasibility of vehicle and network parameters, as well as the feasibility of operational schedules. This will enable future missions to benefit from using these models throughout the full design, test, and fly cycle. In particular, vehicle and network parameters and schedules can be verified prior to being implemented, during mission operations, and can also be updated in near real-time with oper- tional performance feedback. Title: Color Distributions of Stars in the WISE Preliminary Data Release Authors: Hunt-Walker, Nicholas; Davenport, J. R. A.; Lewis, A. R.; Ruan, J.; Anderson, L.; AlSayyad, Y.; Becker, A.; Ivezic, Z. Bibcode: 2012AAS...21915216H Altcode: We present a preliminary characterization of the Galactic stellar populations from the Wide-field Infrared Space Explorer (WISE) Preliminary Data Release. We trace the main sequence color locus in 16 dimensions using a matched sample between IRAS, SDSS and 2MASS for several million stars. This exquisite characterization of "normal” stars enables efficient and robust searches for non-main-sequence stars. For example, the excellent faint limit of WISE yields a sample of AGB candidates using the 4.6, 12, and 22 micron bandpasses that exceeds the IRAS AGB catalog by up to an order of magnitude. Our preliminary analysis suggests that the WISE database will be a goldmine for studies of Galactic stellar populations. Title: OT2_landerso_1: Tracing Galactic Metallicity with Herschel Authors: Anderson, L. Bibcode: 2011hers.prop.1692A Altcode: Galactic abundances trace the processing of primordial elements by stars from the birth of the Milky Way to the present day. HII regions, because of their short lifetimes, are ideal targets for abundance determinations because they sample the current state of the interstellar medium. We propose to observe the [OIII], [NIII], and [NII] lines of 31 well-studied Galactic HII regions with the PACS spectrometer to derive the oxygen and nitrogen abundances. We hope to address two long-standing problems in Galactic abundance measurements: 1) abundances traced in the far-infrared show discrepancies with those in the optical, and 2) HII region electron temperatures derived from radio observations, which can be used as a proxy for metallicity, are not well calibrated with abundance measurements. Title: Dust in molecular clumps from the Hi-GAL survey Authors: Marshall, D. J.; Montier, L. A.; Ristorcelli, I.; Anderson, L.; Bernard, J. P.; Brunt, C.; Martin, P.; Mottram, J.; Paradis, D.; Rodon, J. Bibcode: 2010sf2a.conf..233M Altcode: Dust properties in molecular clouds may give clues to the star formation process.By using recent observations of dust and gas emission, we seek to constrain the dust properties in discrete molecular clumps in the plane of the Milky Way.Using observations of the interstellar gas, we separate observed dust emission from the Hi-GAL survey, using the Herschel Space Observatory, into discrete line of sight components. A new dust spectral inversion technique is used where the dust emission is assumed to be a linear sum of a finite number of components, where the emission from each component follows a modified blackbody emission law. We are able to obtain the dust properties in over 60 molecular clumps in a 4 square degree zone centred on l=30o, b=0o. The dust in a few of the molecular clumps is found to be warmer than the dust associated with the atomic phase of the gas. This suggests that these clumps are not heated solely by the interstellar radiation field, but also contain an internal heating source suggesting the onset of an initial stage of star formation. Title: Clouds, filaments, and protostars: The Herschel Hi-GAL Milky Way Authors: Molinari, S.; Swinyard, B.; Bally, J.; Barlow, M.; Bernard, J. -P.; Martin, P.; Moore, T.; Noriega-Crespo, A.; Plume, R.; Testi, L.; Zavagno, A.; Abergel, A.; Ali, B.; Anderson, L.; André, P.; Baluteau, J. -P.; Battersby, C.; Beltrán, M. T.; Benedettini, M.; Billot, N.; Blommaert, J.; Bontemps, S.; Boulanger, F.; Brand, J.; Brunt, C.; Burton, M.; Calzoletti, L.; Carey, S.; Caselli, P.; Cesaroni, R.; Cernicharo, J.; Chakrabarti, S.; Chrysostomou, A.; Cohen, M.; Compiegne, M.; de Bernardis, P.; de Gasperis, G.; di Giorgio, A. M.; Elia, D.; Faustini, F.; Flagey, N.; Fukui, Y.; Fuller, G. A.; Ganga, K.; Garcia-Lario, P.; Glenn, J.; Goldsmith, P. F.; Griffin, M.; Hoare, M.; Huang, M.; Ikhenaode, D.; Joblin, C.; Joncas, G.; Juvela, M.; Kirk, J. M.; Lagache, G.; Li, J. Z.; Lim, T. L.; Lord, S. D.; Marengo, M.; Marshall, D. J.; Masi, S.; Massi, F.; Matsuura, M.; Minier, V.; Miville-Deschênes, M. -A.; Montier, L. A.; Morgan, L.; Motte, F.; Mottram, J. C.; Müller, T. G.; Natoli, P.; Neves, J.; Olmi, L.; Paladini, R.; Paradis, D.; Parsons, H.; Peretto, N.; Pestalozzi, M.; Pezzuto, S.; Piacentini, F.; Piazzo, L.; Polychroni, D.; Pomarès, M.; Popescu, C. C.; Reach, W. T.; Ristorcelli, I.; Robitaille, J. -F.; Robitaille, T.; Rodón, J. A.; Roy, A.; Royer, P.; Russeil, D.; Saraceno, P.; Sauvage, M.; Schilke, P.; Schisano, E.; Schneider, N.; Schuller, F.; Schulz, B.; Sibthorpe, B.; Smith, H. A.; Smith, M. D.; Spinoglio, L.; Stamatellos, D.; Strafella, F.; Stringfellow, G. S.; Sturm, E.; Taylor, R.; Thompson, M. A.; Traficante, A.; Tuffs, R. J.; Umana, G.; Valenziano, L.; Vavrek, R.; Veneziani, M.; Viti, S.; Waelkens, C.; Ward-Thompson, D.; White, G.; Wilcock, L. A.; Wyrowski, F.; Yorke, H. W.; Zhang, Q. Bibcode: 2010A&A...518L.100M Altcode: 2010arXiv1005.3317M We present the first results from the science demonstration phase for the Hi-GAL survey, the Herschel key program that will map the inner Galactic plane of the Milky Way in 5 bands. We outline our data reduction strategy and present some science highlights on the two observed 2° × 2° tiles approximately centered at l = 30° and l = 59°. The two regions are extremely rich in intense and highly structured extended emission which shows a widespread organization in filaments. Source SEDs can be built for hundreds of objects in the two fields, and physical parameters can be extracted, for a good fraction of them where the distance could be estimated. The compact sources (which we will call cores' in the following) are found for the most part to be associated with the filaments, and the relationship to the local beam-averaged column density of the filament itself shows that a core seems to appear when a threshold around AV ~ 1 is exceeded for the regions in the l = 59° field; a AV value between 5 and 10 is found for the l = 30° field, likely due to the relatively higher distances of the sources. This outlines an exciting scenario where diffuse clouds first collapse into filaments, which later fragment to cores where the column density has reached a critical level. In spite of core L/M ratios being well in excess of a few for many sources, we find core surface densities between 0.03 and 0.5 g cm-2. Our results are in good agreement with recent MHD numerical simulations of filaments forming from large-scale converging flows.

Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. Title: Galactic cold cores: Herschel study of first Planck detections Authors: Juvela, M.; Ristorcelli, I.; Montier, L. A.; Marshall, D. J.; Pelkonen, V. -M.; Malinen, J.; Ysard, N.; Tóth, L. V.; Harju, J.; Bernard, J. -P.; Schneider, N.; Verebélyi, E.; Anderson, L.; André, P.; Giard, M.; Krause, O.; Lehtinen, K.; Macias-Perez, J.; Martin, P.; McGehee, P. M.; Meny, C.; Motte, F.; Pagani, L.; Paladini, R.; Reach, W.; Valenziano, L.; Ward-Thompson, D.; Zavagno, A. Bibcode: 2010A&A...518L..93J Altcode: Context. We present the first results from the project Galactic cold cores, where the cold interstellar clouds detected by the Planck satellite are studied with Herschel photometric observations. The final Planck catalogue is expected to contain several thousand sources. The Herschel observations during the science demonstration phase provided the first glimpse into the nature of these sources.
Aims: The main goal of the project is to derive the physical properties of the cold core population revealed by Planck. We examine three fields and confirm the Planck detections with Herschel data, which we also use to establish the evolutionary stage of the identified cores.
Methods: We study the morphology and spectral energy distribution of the sources using the combined wavelength coverage of Planck and Herschel. The dust colour temperatures and emissivity indices are determined. The masses of the cores are determined with distance estimates which are taken from the literature and are confirmed by kinematic and extinction information.
Results: The observations reveal extended regions of cold dust with dust colour temperatures down to Tdust ~ 11 K. The fields represent different evolutionary stages ranging from a quiescent, cold filament in Musca to regions of active star formation in Cepheus.
Conclusions: The Herschel observations confirm that the all-sky survey of Planck is capable of making a large number of new cold core detections. Our results suggest that many of the sources may already have left the pre-stellar phase or are at least closely associated with active star formation. High-resolution Herschel observations are needed to establish the true nature of the Planck detections.

Planck (http://www.esa.int/Planck) is a project of the European Space Agency - ESA - with instruments provided by two scientific consortia funded by ESA member states (in particular the lead countries: France and Italy) with contributions from NASA (USA), and telescope reflectors provided in a collaboration between ESA and a scientific Consortium led and funded by Denmark.Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. Title: Commissioning the Spectrographs for the Baryon Oscillation Spectroscopic Survey (BOSS) Authors: Bhardwaj, Vaishali; Dawson, K.; Anderson, L.; Bizyaev, D.; Brewington, H.; Brown, P.; Eisenstein, D. J.; Harding, P.; Malanushenko, E.; Malanushenko, V.; Maraston, C.; Olmstead, M.; Oravetz, D.; Pan, K.; Roe, N.; Schlegel, D. J.; Shelden, A.; Simmons, A.; Snedden, S.; Stromback, G. Bibcode: 2010AAS...21547102B Altcode: 2010BAAS...42..517B The Baryon Oscillation Spectroscopic Survey (BOSS) on the Sloan Telescope will map 1.4 million galaxies at z < 0.7 and 160,000 QSOs at 2.2 < z < 3.5. Operations began in September 2009 and will continue through June 2014. BOSS features rebuilt spectrographs that improve the throughput and extend the wavelength coverage to span 3600 to 10,000 Ang. We report on the commissioning of the spectroscopic system. Title: An Algorithm for the Simultaneous Solution of Thousands of Transfer Equations under Global Constraints Authors: Anderson, Lawrence S. Bibcode: 2009nrt..book..163A Altcode: No abstract at ADS Title: Speckle Imaging with an Electron-multiplying CCD Camera at the WIYN Telescope Authors: Horch, Elliott; Anderson, L.; DeSousa, M.; van Altena, W. F. Bibcode: 2009DDA....40.1604H Altcode: Electron-multiplying CCD (EMCCD) cameras have extremely strong characteristics for speckle imaging including high quantum efficiency, extremely low effective read noise, and high bandwidth. We report on our first results for binary star astrometry and photometry using an Andor iXon EMCCD at the WIYN 3.5-m Telescope at Kitt Peak. We find that diffraction-limited image reconstructions can be achieved to approximately 15th magnitude and that the device appears to deliver reliable differential photometry of the components of binary star systems. Some implications for stellar astrophysics are discussed. Title: Milky Way HII Regions: From A GLIMPSE To A Stare Authors: Bania, Thomas M.; Anderson, L. Bibcode: 2008AAS...212.1801B Altcode: 2008BAAS...40..212B The completion of the SPITZER Legacy GLIMPSE survey, the BU-FCRAO 13-CO Galactic Ring Survey (GRS), the HI VLA Galactic Plane Survey (VGPS), the Multi-Array Galactic Plane Imaging Survey (MAGPIS), and the imminent release of the SPITZER Legacy MIPSGAL survey together enable for the first time a multi-wavelength analysis of the physical properties and evolutionary state of a large sample of inner Galaxy HII regions. Existing radio recombination line surveys show that nearly 300 HII regions are located in the zone where GLIMPSE and GRS overlap. Most of the sources are not optically visible. The HII region radio recombination line position and velocity targets a location where GRS 13-CO and MAGPIS/VGPS 20/21 cm continuum images show the distribution and relative geometry of molecular and ionized gas. The SPITZER GLIMPSE and MIPSGAL mid-infrared mosaic images reveal the highly embedded star cluster that ionizes the nebula, probe the distribution of the warm dust, and trace the polycyclic aromatic hydrocarbon emission from the photo-dissociation region that lies between the molecular and ionized zones. The VGPS HI survey is critical to this effort because HI absorption against the thermal continuum from the HII region can be used to resolve the kinematic distance ambiguity. Knowing the distance, one can derive the intrinsic physical properties of the nebula, turning column densities and line intensities into masses and luminosities. Compiling the physical properties of the ionized, atomic, and molecular components of this large sample of star forming regions in all stages of evolution and line of sight geometries will provide a fundamental database for studies of the evolution of the interstellar medium and the Giant Molecular Cloud/HII region/Star Cluster/Supernova Bubble life-cycle. Here we give several case study examples of individual Galactic HII regions. Title: Tracing Ghost Cavities with Low Frequency Radio Observations Authors: Clarke, T.; Blanton, E.; Sarazin, C. L.; Kassim, N.; Anderson, L.; Schmitt, H.; Gopal-Krishna; Neumann, D. M. Bibcode: 2007hvcg.conf..124C Altcode: 2006astro.ph.12595C We present X-ray and multi-frequency radio observations of the central radio sources in several X-ray cavity systems. We show that targeted radio observations are key to determining if the lobes are being actively fed by the central AGN. Low frequency observations provide a unique way to study both the lifecycle of the central radio source as well as its energy input into the ICM over several outburst episodes. Title: Tracing AGN Outbursts in Clusters Cores using X-ray and Low Frequency Radio Observations Authors: Clarke, Tracy E.; Blanton, E.; Sarazin, C.; Kassim, N.; Anderson, L. Bibcode: 2006HEAD....9.1331C Altcode: 2006BAAS...38..371C X-ray observations of the thermal gas in the central regions of

cooling core clusters have revealed spectacular details of the

interactions between the central radio sources and the surrounding

thermal intracluster medium. In addition to depressions and filaments

associated with the active central radio source, there are a number of

cases of 'ghost cavities' in the thermal gas which may trace buoyant

lobes from past radio outbursts. The ghost cavities provide details on

the lifecycle of the central radio sources as well as their energy

input into the ICM. We present a detailed X-ray and multi-frequency

radio analysis of the central radio sources in several of these ghost

cavity systems. Our new low frequency radio observations allow us

to trace multiple cycles of radio outbursts and reveal evidence of

radio emission filling X-ray tunnels in both Abell 2597 and Abell 262.

Basic research in radio astronomy at the NRL is supported by the Office of Naval Research. Title: XRF 020427: sudden ionospheric disturbance (SID). Authors: Fishman, G. J.; Woods, P. M.; Hossfield, C.; Anderson, L. Bibcode: 2002GCN..1394....1F Altcode: No abstract at ADS Title: A New Improved Balloon System at ESRANGE Authors: Anderson, L. Bibcode: 1997ESASP.397..439A Altcode: 1997erbp.conf..439A No abstract at ADS Title: Solar and Stellar Atmospheres in the Graduate Curriculum Authors: Anderson, L. S. Bibcode: 1996AAS...188.3205A Altcode: 1996BAAS...28..867A The study of semi-infinite radiating media has reached a critical stage in its development. Back in Eddington's day, analytic theory blossomed and set seed for the present, with fertilization from quantum mechanics and stellar spectroscopy. In the 1970's, computers became powerful enough to integrate all the interactions of radiation with cosmic plasmas in simple geometries. Today, the classical atmosphere problem, consisting of atoms and molecules stratified in a simple one-dimensional geometry and in hydrostatic and radiative equilibrium with a constant radiative luminosity, essentially has been solved. Such model solutions can (or should) be found for most of the HR Diagram with a little exploration of the internet. Because of this completion of a global problem, work in the field has fragmented. The classical models are pretty good at matching today's high signal-to-noise observations. The failures of the models cannot be as easily classified as the original stellar spectra the models were designed to match. These failures vary between individual stars and/or small classes of stars by as much as the error itself, so it is harder to make general statements and for workers to compare results. The non-classical physics in one area of the HR Diagram might be completely different from that of a nearby area, or even from one star to the next in the same area. How do we train today's students to approach this scattered disparity? How do we excite students to carry on in the steps of Eddington, Mihalas, Kurucz, and the many other contributors to the solution of the classical problem? What, if any, are the outstanding problems of global significance? Our tools are extremely powerful; any department or personal workstation can do the work of yesterday's Cray, and the supercomputers today can take on the challenge of multi-dimentional moving media. Title: Infrared line emission in 10 Lacertae. Authors: Murdoch, K. A.; Drew, J. E.; Anderson, L. S. Bibcode: 1994A&A...284L..27M Altcode: We report the presence of Brα and Brγ emission features in the infrared spectrum of the O9V MK standard star 10 Lac. Waters et al. (1993) have reported similar emission in the spectrum of the B0.2V star τ Sco and have suggested that the emission is from a low-density disk and that τ Sco is a mild, pole-on member of the Be class of stars. We argue that such emission features arise as a natural consequence of the structure of these stars'outer atmospheres, thus eliminating the need to introduce departures from spherical symmetry. Indeed, theoretical Brα and Brγ line profiles calculated using stellar parameters derived from 10 Lac by Grigsby et al. (1992) show a striking similarity to our observations Title: A Determination of the Basic Atmospheric Parameters of phi Cassiopeiae Authors: Rosenzweig, Patricia; Anderson, Lawrence Bibcode: 1993ApJ...411..207R Altcode: By constructing non-LTE spherical model atmospheres, we have calculated a theoretical distribution of the emergent radiation that best matches the observed distribution of the supergiant Phi Cas, and so derived its effective temperature, surface gravity, and radius. Since Phi Cas is very likely a member of the open cluster NGC 457, we made extinction corrections using the extinction determined for this cluster by Rosenzweig and Morrison (1986). Moreover, the theoretical atmospheres used for the comparison are line-blanketed models in hydrostatic and radiative equilibrium. Several tests have demonstrated that the models are reliable. The comparison of the observed UV and visible energy distributions and the H-delta, Ca II K, and Mg II h and k line profiles with the theoretical results indicates that the best model for Phi Cas has T(eff) = 7200 +/- 100 K, log g = 0.4 +/- 0.1, and R* = 263 +/- 34 R(solar). These results imply a mass of 6.3 +/- 3.6 solar masses, which is lower than but within the error of the mass of the main-sequence turnoff point in NGC 457. Title: PAM: a Code for Non-LTE Line Blanketed Atmospheres Authors: Anderson, L. S. Bibcode: 1992ASPC...26..509A Altcode: 1992csss....7..509A No abstract at ADS Title: Non--LTE, Line-blanketed Model Atmospheres for Late O- and Early B-Type Stars Authors: Grigsby, James A.; Morrison, Nancy D.; Anderson, Lawrence S. Bibcode: 1992ApJS...78..205G Altcode: The use of non-LTE line-blanketed model atmospheres to analyze the spectra of hot stars is reported. The stars analyzed are members of clusters and associations, have spectral types in the range O9-B2 and luminosity classes in the range III-IV, have slow to moderate rotation, and are photometrically constant. Sampled line opacities of iron-group elements were incorporated in the radiative transfer solution; solar abundances were assumed. Good to excellent agreement is obtained between the computed profiles and essentially all the line profiles used to fix the model, and reliable stellar parameters are derived. The synthetic M II 5581 equivalent widths agree well with the observed ones at the low end of the temperature range studied, but, above 25,000 K, the synthetic line is generally stronger than the observed line. The behavior of the observed equivalent widths of N II, N III, C II and C III lines as a function of Teff is studied. Most of the lines show much scatter, with no consistent trend that could indicate abundance differences from star to star. Title: Line Blanketing Without LTE - the Effect on Diagnostics for B-Type Stars Authors: Anderson, L.; Grigsby, J. A. Bibcode: 1991ASIC..341..365A Altcode: 1991sabc.conf..365A No abstract at ADS Title: The photosphere as a radiative boundary. Authors: Anderson, Lawrence S.; Avrett, Eugene H. Bibcode: 1991sia..book..670A Altcode: The authors review the role of the photosphere as a radiative boundary for the solar interior, concentrating on semi-empirical and a priori models for the structure and emergent radiation. Contents: 1. Introduction. 2. Plane-parallel models. 3. Departures from plane-parallel structure. 4. Dynamical convection models. Title: Line Blanketing Without Lts - Simple and Complex Spectra Authors: Anderson, L. Bibcode: 1991ASIC..341...29A Altcode: 1991sabc.conf...29A No abstract at ADS Title: Non-LTE line blanketing with elements 1 - 28. Authors: Anderson, Lawrence Sven Bibcode: 1990ASPC....7...77A Altcode: 1990phls.work...77A The author reports on the status of a continuing effort to calculate non-LTE models of stellar atmospheres including the blanketing of several million atomic transitions. In addition to the multi-frequency / multi-gray algorithm for solving many coupled equations of radiative transfer, the author has developed two independent ways of statistically treating the ensemble of transitions within an ion in non-LTE. The millions of real transitions are reduced to about 800 model transitions in 22 ions, well within the capabilities of the transfer algorithm. The author presents a model for a main sequence B-type star with an effective temperature of 25,000K, a surface gravity of 104cm s-2, and solar abundances. Title: Chromospheric Thermal Equilibrium - Varying Effective Temperature and Gravity Authors: Anderson, L. S. Bibcode: 1990ASPC....9..110A Altcode: 1990csss....6..110A No abstract at ADS Title: Model Solar Chromosphere with Prescribed Heating Authors: Anderson, Lawrence S.; Athay, R. Grant Bibcode: 1989ApJ...346.1010A Altcode: Computed model solar chromospheres for prescribed departures from radiative equilibrium are specified in terms of the local mechanical (nonradiative) heat input. The computations are fully non-LTE and include millions of spectral lines. From the variety of models considered, the requirements on the heat input for a positive temperature gradient, dT/dh, in different layers of the chromosphere are discussed. The derived radiative cooling function for different models show that the cooling function is model-dependent. By comparing the computed models with the Vernazza, Avrett, and Loeser (1981) models, it is shown that the VAL-C model is characterized by a total heat flux 1.4 x 10 to the 7th ergs/sq cm/per sec, most of which is dissipated near the base of the temperature plateau. Half of the radiation loss is provided by Fe II, with Ca II, Mg II, and H playing important, but secondary, roles. CO molecules and H(-) are of lesser importance even near the temperature minimum, except in cases of minimal heating. Title: Line Blanketing without Local Thermodynamic Equilibrium. II. A Solar-Type Model in Radiative Equilibrium Authors: Anderson, Lawrence S. Bibcode: 1989ApJ...339..558A Altcode: A statistical solution for the problem of non-LTE radiative transfer in the millions of atomic transitions responsible for line blanketing is proposed which takes into account the influence of scattering on the atomic populations. A multifrequency/multigray algorithm is used to analyze the thermal equilibrium. Although CO is shown to cool the upper atmosphere to a boundary temperature of 2640 K, the molecule has little influence in the region of the solar temperature minimum. Title: An Atlas of B-type Stellar Atmosphere Models with NonLTE Line Blanketing Authors: Anderson, L. S. Bibcode: 1989BAAS...21..742A Altcode: No abstract at ADS Title: Chromospheric and Coronal Heating Authors: Anderson, Lawrence S.; Athay, R. Grant Bibcode: 1989ApJ...336.1089A Altcode: From computations for a theoretical model chromosphere matched to the empirical model of Vernazza, Avrett, and Loeser published in 1981, it is concluded that the required magnitude and mass dependence of the heat input are compatible with heating by sound waves whose velocity amplitude is near the sound speed. However, the required rate of heat input per gram increases markedly at the top of the neutral chromosphere, and a different form of heating appears necessary in the corona and transition region. Title: A New Spherical, Non-LTE, Blanketed Model Stellar Atmosphere for ø Cas(FOla) Authors: Rosenzweig, P.; Anderson, L. S. Bibcode: 1988BAAS...20..698R Altcode: No abstract at ADS Title: Statistical Mechanics of Partially Ionized Stellar Plasmas: The Planck-Larkin Partition Function, Polarization Shifts, and Simulations of Optical Spectra Authors: Dappen, Werner; Anderson, Lawrence; Mihalas, Dimitri Bibcode: 1987ApJ...319..195D Altcode: We discuss a recent controversy about the Planck-Larkin partition function, and present optical simulations of high-quality spectra from laboratory hydrogen plasmas (Wiese, Kelleher, and Paquette) using several partition function formalisms. We point out that the controversy has arisen from a misunderstanding about the use of the Planck-Larkin partition function. A Planck-Larkin cancellation may still have its place in equations of state that are based on quantum-statistical many-body theory (i.e., the "physical picture"). However, experimental evidence shows that it is inconsistent to use the Planck-Larkin partition function as the internal partition function in simple models of reacting gases (i.e., the "chemical picture"). Moreover, the more sophisticated equations of state of the physical picture will have to be subjected to the same comparison with experimental data. We also address the question of plasma polarization shifts of bound-state energies. We discuss the static-screened Coulomb potential (SSCP) as an atomic potential: from theoretical considerations and observational constraints we conclude that it should not be used. The only useful result of the SSCP potential its prediction of the number of excited be obtained by alternative means, e.g., by an occupation probability formalism. Title: Radiative Cooling in the Solar Chromosphere Authors: Anderson, L. S.; Athay, R. G. Bibcode: 1987BAAS...19R.930A Altcode: No abstract at ADS Title: An Algorithm for the Simultaneous Solution of Thousands of Transfer Equations under Global Constraints Authors: Anderson, Lawrence S. Bibcode: 1987nrt..book..163A Altcode: No abstract at ADS Title: Line blanketing without local thermodynamic equilibrium. I - A hydrostatic stellar atmosphere with hydrogen, helium, and carbon lines Authors: Anderson, L. S. Bibcode: 1985ApJ...298..848A Altcode: A numerical code designed to calculate radiation transport and atmospheric structure under the constraints of statistical equilibrium in atomic transitions and radiative and hydrostatic equilibrium in the medium has been applied to a stellar atmosphere with effective temperature of 35,000 K and surface gravity of 10,000 cm/sq sec. The calculation includes 93 bound-free transitions and 128 bound-bound transitions (112 including radiative rates in 143 multiplet components) between 83 states in 29 ions of nine cosmically abundant species. The calculated depth-dependence of the electron temperature superficially resembles that in local thermodynamic equilibrium (LTE), but the ionization balance shifts toward higher ion states. The transition dominating the thermodynamic equilibrium shifts from C III 977 A in LTE to C IV 1548-1551 A in non-LTE, and the electron temperatures in the upper atmosphere drop by 15 percent. In addition, the ultraviolet continua with energies h-nu greater than 24 eV are from 5 to 100 times stronger in non-LTE. Little change in the hydrogen spectra from previous non-LTE models occurs. The implications for spectral synthesis and ionization in stellar winds are discussed. Title: A code for line blanketing without local thermodynamic equilibrium. Authors: Anderson, L. S. Bibcode: 1985ASIC..152..225A Altcode: 1985pssl.proc..225A A numerical code has been written which is designed to calculate radiation transport and atmospheric structure under the constraints of statistical equilibrium in atomic transitions and radiative and hydrostatic equilibrium in the medium. It uses a multi-frequency/multi-grey algorithm which admits the inclusion of many spectral lines in full statistical equilibrium. The program can comfortably accept up to about 300 specific lines arising from about 30 lower states and any number of continua. By way of example, the author presents a model of a stellar atmosphere with effective temperature 35000K and surface gravity 104cm s-2. Title: Frequency dependence of Q in the mantle underlying the shield areas of eurasia Authors: der, Z. A.; Lees, A. C.; Cormier, V. F.; Anderson, L.; Burnetti, J. Bibcode: 1985tege.rept.....D Altcode: In Part I the results of short and intermediate period data analyses for the determination of a frequency dependent Q model of the mantle under the shield areas of Eurasia are presented. The spectra of short period P waves from nuclear explosions in the 1-8 Hz frequency range give t* sub p = approx. 0.15-0.2 seconds. Part II presents analyses of long period data. Long period multiple S and ScS phases observed in northern Europe were analyzed to determine mantle attenuation in the 0.02 to 0.2 Hz range under the Eurasian shield. Two groups of events are used: deep Far-Eastern earthquakes and large earthquakes near the edges of the shield areas of Eurasia. Part III provides the Q model. A large set of broad band data was analyzed to determine the frequency and depth dependence of Q for P and S waves under the northern shield areas of Eurasia. A wide range of techniques utilizing spectra, amplitude ratios and waveform modeling were used to derive apparent and absolute t* estimated for P and S waves covering the seismic band between 0.01 to 10 Hz. A supplement discusses methodologies for estimating t*(f) from Short Period Body Waves and Regional Variations of t*(f) in the United States. Title: Stellar images derived from rotation broadening : AW Ursae Majoris. Authors: Anderson, L.; Stanford, D.; Leininger, D. Bibcode: 1983ApJ...270..200A Altcode: New spectroscopic observations of the W UMa star AW Ursae Majoris are interpreted by retrieving the star's continuum Doppler redistribution function through the Fourier deconvolution of broadened strong lines by a standard flux profile, and the star's shape and surface brightness distribution are derived. The graphical approach to rotation broadening is briefly reviewed, and the implicit assumptions are stated. The observations and data reduction method are described, and the assumption that the locally emitted spectral profile is uniform over the stellar surface is examined. The Doppler redistribution functions obtained for AW UMa are consistently too narrow and asymmetric for the assumed geometry of the system. It is concluded that a large fraction of the primary component is covered with a solarlike plage centered on the side away from the secondary, which radically alters the local line equivalent widths. Title: Non-LTE Line Blanketing: A Code and Some Early Results Authors: Anderson, L. S. Bibcode: 1982BAAS...14..921A Altcode: No abstract at ADS Title: X-rays and HZ Herculis Authors: Anderson, L. Bibcode: 1981ApJ...244..555A Altcode: A detailed calculation of the structural and radiant characteristics of the X-ray-illuminated atmosphere of HZ Her is necessary before it is possible to substract its contribution from the total light and study the more subtle effects of nonuniform illumination and contributions from other system components. It is shown that an X-ray-irradiated atmosphere can be divided into four distinct zones. In order of decreasing height, these zones are a nearly isothermal photosphere strongly coupled to its own thermal radiation with additional heating by hard X-ray photoionization and Compton scattering, and two sharp transitions to a high-temperature corona in equilibrium with the X-rays. The corona becomes gravitationally unbound a short distance (compared to the binary separation) above the transition and expands into a stellar wind. Both the lines and continuum observations, when compared with emergent radiation calculations, are consistent with an incident spectrum containing as much flux below hv = 1 keV as above hv = 1 keV. Title: On various criticisms of the contact discontinuity model Authors: Shu, F. H.; Lubow, S. H.; Anderson, L. Bibcode: 1980ApJ...239..937S Altcode: We discuss various criticisms raised recently by Lucy and Wilson, by Papaloizou and Pringle, and by Smith, Robertson, and Smith against the contact discontinuity model for contact binaries. In the process we discover a promising means by which the filled fraction occupied by the common envelope could, in principle, be determined mechanistically for a contact binary of given total mass, angular momentum, initial chemical composition, and age. Title: Comparison of Submillimeter and CO Brightness in Orion and MONOCEROS-R2 Authors: Cudaback, D.; Anderson, L.; Lynch, D.; Smith, J. Bibcode: 1980IAUS...87..135C Altcode: No abstract at ADS Title: Rotation broadening and the shapes of W Ursae Majoris Stars Authors: Anderson, L.; Raff, M.; Shu, F. H. Bibcode: 1980IAUS...88..485A Altcode: Rotation broadening functions are extracted from the spectra of W Ursae Majoris Stars. A fast Fourier transform is used to deconvolve photographic spectra, covering some 500 A including dozens of strong lines, with equivalent spectra from non-rotating stars of similar spectral type. The resulting rotation functions contain information about global features such as the shape of the stellar surface (e.g. mass ratio and degree of contact), gravity brightening and limb darkening. Preliminary data on the stars VW Cep and ER Vul are presented. The rotation function of the former reveals the presence of the third component found visually by Heintz (1975), while that of the latter shows it to be detached and have mass ratio 0.9. Title: A theoretical atlas of light curves and rotation broadening functions for contact binary stars. Authors: Anderson, L.; Shu, F. H. Bibcode: 1979ApJS...40..667A Altcode: Bolometric light curves and rotation broadening functions of contact binaries are computed for a grid of values of mass ratio, filled fraction, and orbital inclination, assuming three different extreme combinations of gravity brightening and limb darkening. The results are presented in a standard graphical format which is readily usable for comparisons with observations. Title: On the structure of contact binaries. III. Mass and energy flow. Authors: Shu, F. H.; Lubow, S. H.; Anderson, L. Bibcode: 1979ApJ...229..223S Altcode: A variety of topics dealing with the mass and energy flow in contact binaries is examined. It is argued that the contact discontinuity hypothesis proposed in earlier communications is both necessary and sufficient to resolve Kuiper's (1941) paradox concerning the existence of contact binaries with unequal components. A detailed qualitative picture of the maintenance by fluid flow of the contact and weak discontinuities of zero-order models in presented. This discussion supplies a description of the mechanism by which the interior luminosities are redistributed to give common envelope luminosities. It also provides order-of-magnitude estimates for the thickness of the transition layer and mixing region that constitute the actual structure of the contact and weak discontinuities. The gas dynamics of mass loss that occurs if stellar evolution should cause a synchronously rotating common surface to try to expand beyond the outer critical surface is calculated. The role of various processes in the problem of the evolution of contact binaries is considered. Title: Rotation Broadening Functions of Selected W Ursae Majoris Stars. Authors: Anderson, L.; Raff, M.; Shu, F. H. Bibcode: 1979BAAS...11..438A Altcode: No abstract at ADS Title: Nucleus-nucleus total cross sections for light nuclei at 1.55 and 2.89 GeV/c per nucleon Authors: Jaros, J.; Wagner, A.; Anderson, L.; Chamberlain, O.; Fuzesy, R. Z.; Gallup, J.; Gorn, W.; Schroeder, L.; Shannon, S.; Shapiro, G.; Steiner, H. Bibcode: 1978PhRvC..18.2273J Altcode: We have measured total cross sections for protons, dueterons, α particles, and 12C on hydrogen, deuterium, helium, and carbon targets at 1.55 and 2.89 GeV/c nucleon using the "good geometry" transmission method. In addition, we measured the inelastic cross sections and elastic slope parameters for reactions initiated by deuterons, α particles, and 12C. Our results are in good agreement with Glauber theory predictions, but the factorization relation σT(AA)=[σT(AB)]2σT(BB) is not a good guide. We find σT~=144(AT13-Ap13-1.48)2 mb and σIN~=78(AT13+Ap13-1.25)2 mb, where AT(Ap) is the atomic mass number of the target (projectile). NUCLEAR REACTIONS 12C(12C, X), (α, X), (d, X), (p, X), E=0.87 and 2.10 GeV/nucleon; measured total cross section, total inelastic cross section, and slope parameter of elastic scattering. Title: The S19 Guidance System for Reduction of Sounding Rocket Dispersion Authors: Anderson, L.; Lundin, S.; Andersson, J. Bibcode: 1978ESASP.135..437A Altcode: 1978esrb.rept..437A The S19 guidance system used to significantly reduce the impact dispersion of sounding rockets is described. With the guidance system, the main contributions to impact dispersion caused by wind errors and thrust misalignment are reduced by a factor of up to ten depending on the comparative unguided case. Therefore, the guidance system will make it possible to launch sounding rockets to much higher altitudes at restricted ranges and will reduce the stand-by time due to severe wind conditions. The modular concept has the advantage that the guidance system, with mirror changes, can be mounted on several different one- or two-stage rockets without any modification of the rocket. Another benefit is that the modular concept permits re-use, since the guidance system can be recovered with the payload. Title: On the role of photospheric convection in W Ursae Majoris stars. Authors: Anderson, L.; Shu, F. H. Bibcode: 1978ApJ...221..926A Altcode: We correct the derivation of the source function in the atmospheres of contact binaries given in an earlier communication by Anderson and Shu. This correction affects the cases when convection is present in the photosphere. In our new treatment photospheric convection is more efficient for reducing limb darkening. This result does not, however, modify the numerical examples considered in our earlier paper. Subject headings: convection - stars: W Ursae Majoris Title: New morphometric data for fresh lunar craters. Authors: Wood, C. A.; Anderson, L. Bibcode: 1978LPSC....9.3669W Altcode: Morphometric relations have been determined for 2598 fresh craters on the lunar nearside using data given in the catalog of Wood and Andersson (1978). For each of five principal morphological types, typified by Albategnius C, Biot, Sosigenes, Triesnecker, and Tycho, statistical relations are documented for the following: crater diameter and depth; floor diameter and crater diameter; central peak height and crater diameter; average wall slope and crater depth; central peak occurrence and crater diameter; occurrence of scallops or terraces and crater diameter. The first four relations generally confirm the conclusions of Pike (1977), but the last two differ from results reported by Smith and Sanchez (1973). Small (diameter less than 20 km) flat-floored craters formed in mare terrains are as much as 10% deeper than those formed in the highlands, and the depths of small bowl-shaped craters reflect even greater dependence on terrain. Larger, scalloped-walled craters are deeper in highland terrain than on the maria. Although wall failure does not occur until the crater diameter reaches 13 km, central peaks are found in flat floor craters as small as 2 km. Title: On the light curves of W Ursae Majoris stars. Authors: Anderson, L.; Shu, F. H. Bibcode: 1977ApJ...214..798A Altcode: We develop a physical theory for the light curves of contact binaries based on the assumption that the dynamical time scale is very short in comparison with the thermal time scale at the base of the common envelope. In contrast with the case for common radiative envelopes, the flux distribution in common convective envelopes does not exhibit any effect of gravity brightening. Combined with a unified treatment of reflection and limb darkening, this result produces Wtype light curves for W UMa stars of spectral type later than F5 if the orbit is inclined by less than approximately 70 90o. The sign of the effect is in rough accord with the observations, but some discrepancy remains concerning the magnitude of the effect. We speculate that the interaction between rapid rotation and convection may contribute to the remaining discrepancy; it may also produce the asymmetry and time variability which are observed in some light curves. Subject headings: stars: binaries - stars: W Ursae Majoris Title: The Minkowski Symposium and summer meeting of the Astronomical Society of the Pacific. Authors: Fawley, W.; Thorstensen, J.; Anderson, L.; Zook, A. Bibcode: 1977Mercu...6....6F Altcode: No abstract at ADS Title: Stellar Atmospheres with Incident Radiation: HZ Herculis. Authors: Anderson, L. S. Bibcode: 1977PhDT.........7A Altcode: The solutions are presented for plane parallel, hydrostatic, radiative, and statistical (non-LTE) equilibrium atmospheres with a variety of incident spectra. The general structure is found to be qualitatively similar to that of previous analyses. The irradiated atmosphere divides onto four distinct zones. The condition that the luminosity of Her X-1 is entirely due to matter overflowing the Roche lobe of HZ Her and falling on a neutron star is sufficient to determine the gas density at the gravitational saddle between the two stars. This density corresponds almost exactly to the density at the top of the photosphere in the irradiated atmosphere, implying that the transition zone is just outside the saddlepoint. It is shown that the fact that the luminosity of Her X-1 is about one-tenth of its Eddington luminosity is related to this finding. Title: On the structure of contact binaries. I. The contact discontinuity. Authors: Shu, F. H.; Lubow, S. H.; Anderson, L. Bibcode: 1976ApJ...209..536S Altcode: The problem of the interior structure of contact binaries is reviewed, and a simple resolution of the difficulties which plague the theory is suggested. It is proposed that contact binaries contain a contact discontinuity between the lower surface of the common envelope and the Roche lobe of the cooler star. This discontinuity is maintained against thermal diffusion by fluid flow, and the transition layer is thin to the extent that the dynamical time scale is short in comparison with the thermal time scale. The idealization that the transition layer has infinitesimal thickness allows a simple formulation of the structure equations which are closed by appropriate jump conditions across the discontinuity. The further imposition of the standard boundary conditions suffices to define a unique model for the system once the chemical composition, the masses of the two stars, and the orbital separation are specified. Title: Statistical Equilibrium Models of the Atmosphere of HZ Herculis. Authors: Anderson, L. Bibcode: 1976BAAS....8..507A Altcode: No abstract at ADS Title: On the Light Curves of W Ursae Majoris Stars. Authors: Anderson, L.; Shu, F. H. Bibcode: 1976BAAS....8R.521A Altcode: No abstract at ADS Title: Development of the S19 Guidance System for the Reduction of Sounding-Rocket Dispersion Authors: Anderson, L.; Anderson, J. Bibcode: 1976ESASP.115..497A Altcode: 1976epsr.conf..497A No abstract at ADS Title: X-rays from degenerate stars. Part II. Authors: Anderson, L. Bibcode: 1976Mercu...5....2A Altcode: No abstract at ADS Title: X-rays from degenerate stars. Part I. Authors: Anderson, L. Bibcode: 1976Mercu...5....6A Altcode: No abstract at ADS Title: On the long-term behavior of the HZ Herculis/Hercules X-1 system. Authors: Anderson, L. Bibcode: 1975ApJ...202..232A Altcode: In accretion models for binary X-ray sources based on Roche-lobe overflow, mass transfer from an otherwise normal, expanding star to a collapsed companion is responsible for the production of X-rays. For a range of time-averaged rates of mass transfer, the instantaneous rate of transfer depends on the X-ray luminosity. Thus the rate may be subject to a feedback instability. We propose that such an instability is responsible for the long-period on-off behavior of HZ Herculis. Subject headings: binaries - X-ray sources Title: The origin and history of the moon. Authors: Anderson, L. Bibcode: 1974Moon...11..440A Altcode: No abstract at ADS Title: Hydrodynamic Atmospheres for Companions of Binary X-ray Sources Authors: Anderson, L.; Arons, J. Bibcode: 1974BAAS....6..280A Altcode: No abstract at ADS Title: Hydrogen emission phenomena in T Tauri stars Authors: Anderson, L.; Kuhi, L. V. Bibcode: 1969CoKon..65...93A Altcode: 1969nppv.conf...93A No abstract at ADS