Search Publications
Calculating the Thermal Structure of Solar Active Regions in Three Dimensions
Linker, Jon A.; Mikić, Zoran; Mok, Yung +1 more
We describe a technique to obtain the temperature and density distribution in an active region for a specified plasma heating model. The technique can be applied in general to determine the magnetic field and thermal structure self-consistently. For simplicity, we illustrate the application of this technique in the limit of small plasma β, in whic…
GEMS: Which Galaxies Dominate the z~0.7 Ultraviolet Luminosity Density?
Heymans, C.; Wolf, C.; Barden, M. +14 more
We combine high-resolution images from GEMS with redshifts and spectral energy distributions from COMBO-17 to explore the morphological types of galaxies that dominate the z~0.7 UV luminosity density. We analyzed rest-frame 280 nm and V-band luminosities of 1483 galaxies with 0.65<z<0.75, combining these with visual morphological classificat…
Star Formation Rates in Cooling Flow Clusters: A UV Pilot Study with Archival XMM-Newton Optical Monitor Data
Mushotzky, R.; Hicks, A. K.
We have analyzed XMM-Newton Optical Monitor UV (180-400 nm) data for a sample of 33 galaxies. Thirty are cluster member galaxies, and nine are central cluster galaxies (CCGs) in cooling flow clusters having mass deposition rates between 8 and 525 Msolar yr-1. By comparing the ratio of UV to 2MASS J-band fluxes, we find a sign…
Molecular Hydrogen in the Damped Lyα Absorber of Q1331+170
Ge, Jian; Meyer, David M.; Bechtold, Jill +1 more
We used HST STIS to obtain the spectrum of molecular hydrogen associated with the damped Lyα system at zabs=1.7765 toward the quasar Q1331+170 at zem=2.084. Strong H2 absorption was detected, with a total H2 column density of N(H2)=(4.45+/-0.36)×1019 cm-2. The molecular h…
Detection of Radial Surface Brightness Fluctuations and Color Gradients in Elliptical Galaxies with the Advanced Camera for Surveys
Blakeslee, John P.; Mei, Simona; Cantiello, Michele +3 more
We study surface brightness fluctuations (SBFs) in a sample of eight elliptical galaxies using the Advanced Camera for Surveys (ACS) Wide Field Channel (WFC) data drawn from the Hubble Space Telescope archive. SBF magnitudes in the F814W bandpass and galaxy colors from F814W, F435W, and F606W images, when available, are presented. Galaxy surface b…
A Wide-Field Hubble Space Telescope Survey of the Cluster Cl 0024+16 at z = 0.4. III. Spectroscopic Signatures of Environmental Evolution in Early-Type Galaxies
Smith, Graham P.; Treu, Tommaso; Smail, Ian +4 more
We report results from a panoramic spectroscopic survey of 955 objects in the field of the rich cluster Cl 0024+1654 (z~=0.4), complementing the HST imaging presented in the first paper in this series. Combining with previous work, we compile a catalog of 1394 unique redshifts in the field of this cluster, including 486 cluster members spread acro…
8-13 µm Spectroscopy of Young Stellar Objects: Evolution of the Silicate Feature
Meyer, Michael R.; Hillenbrand, Lynne A.; Blake, Geoffrey A. +1 more
Silicate features arising from material around pre-main-sequence stars are useful probes of the star and planet formation process. In order to investigate possible connections between dust processing and disk properties, 8-13 µm spectra of 34 young stars, exhibiting a range of circumstellar environments and including spectral types A-M, were…
Complex X-Ray Absorption and the Fe Kα Profile in NGC 3516
Turner, T. J.; Kraemer, S. B.; Reeves, J. N. +2 more
We present data from simultaneous Chandra, XMM-Newton, and BeppoSAX observations of the Seyfert 1 galaxy NGC 3516, taken during 2001 April and November. We have investigated the nature of the very flat observed X-ray spectrum. Chandra grating data show the presence of X-ray absorption lines, revealing two distinct components of the absorbing gas, …
Self-Consistent Magnetohydrodynamic Modeling of a Coronal Mass Ejection, Coronal Dimming, and a Giant Cusp-shaped Arcade Formation
Shibata, Kazunari; Chen, P. F.; Isobe, Hiroaki +3 more
We performed magnetohydrodynamic simulations of coronal mass ejections (CMEs) and associated giant arcade formations, and the results suggest new interpretations of observations of CMEs. We performed two cases of the simulation: with and without heat conduction. Comparing between the results of the two cases, we found that the reconnection rate in…
Discovery of a Primitive Damped Lyα Absorber near an X-Ray-bright Galaxy Group in the Virgo Cluster
Bowen, David V.; Tripp, Todd M.; Jenkins, Edward B. +3 more
We present a new ultraviolet echelle spectrum of PG 1216+069, obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope, that reveals damped Lyα absorption, as well as O I, C II, Si II, and Fe II absorption lines, at zabs=0.00632 near the NGC 4261 galaxy group in the periphery of the Virgo Cluster. The a…