Search Publications
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…
The Optical and Ultraviolet Spectral Energy Distributions of Short-Period Black Hole X-Ray Transients in Outburst
Hynes, R. I.
We compile optical and UV spectra of a sample of ``typical'' short-period black hole X-ray transients in outburst. We also survey determinations of interstellar extinction and distance to deredden spectra and compare absolute fluxes. Hence, we perform a comparative study of the broadband spectral energy distributions (SEDs). We find that, given su…
The Stellar Populations in the Central Parsecs of Galactic Bulges
Filippenko, Alexei V.; Ho, Luis C.; Shields, Joseph C. +5 more
We present Hubble Space Telescope blue spectra at intermediate spectral resolution for the nuclei of 23 nearby disk galaxies. These objects were selected to have nebular emission in their nuclei and span a range of emission-line classifications, as well as Hubble types. In this paper we focus on the stellar population as revealed by the continuum …
The White Dwarf Cooling Sequence in NGC 6791
Anderson, Jay; Salaris, Maurizio; Bedin, Luigi R. +4 more
In the old, populous, and metal-rich open cluster NGC 6791, we have used deep Hubble Space Telescope Advanced Camera for Surveys images to track the white dwarf cooling sequence down to mF606W~=28.5. The white dwarf luminosity function shows a well-defined peak at mF606W~=27.4 and a bending to the blue in the color-magnitude …
GRB 020410: A Gamma-Ray Burst Afterglow Discovered by Its Supernova Light
Garnavich, Peter; Tanvir, Nial; Hjorth, Jens +19 more
We present the discovery and monitoring of the optical transient (OT) associated with GRB 020410. The fading OT was found by Hubble Space Telescope (HST) observations taken 28 and 65 days after burst at a position consistent with the X-ray afterglow, making this the first time that the optical afterglow of a gamma-ray burst (GRB) has been discover…