Search Publications
Evolution of Infrared-selected Galaxies in Z approximately 0.4 Clusters
Dickinson, Mark; Stanford, S. A.; Eisenhardt, P. R. M.
Wide-field optical and near-IR (JHK) imaging is presented for two rich galaxy clusters: Abell 370 at z = 0.374 and Abell 851 (Cl 0939+47) at z = 0.407. The new data are combined to produce colors sampling the 0.55-1.65 micron range in the rest frame. Galaxy catalogs selected from the near-IR images are 90% complete to a limiting magnitude approxim…
The DIM Inner Accretion Disk of the Quiescent Black Hole A0620-00
Remillard, Ronald A.; McClintock, Jeffrey E.; Horne, Keith
We observed the X-ray nova A0620-00 with the Hubble Space Telescope (HST) Faint object Spectrograph 16 yr after its 1975 outburst. We present a single spectrum (1250-4750 A), which is approximately an average over a full 7.8 hr orbital cycle of the source. The continuum can be fitted approximately by a blackbody model with T = 9000 K and a small p…
The Pulsation Index, Effective Temperature, and Thickness of the Hydrogen Layer in the Pulsating DA White Dwarf G117-B15A
Koester, D.; Percival, J. W.; van Citters, G. W. +6 more
We have measured the amplitude of the 215 s pulsation of the pulsating DA white dwarf, or ZZ Ceti star, G117-B15A in six passbands with effective wavelengths from 1570 to 6730 A. We find that the index of the pulsation is l = 1 with a high degree of confidence, the first unambiguous determination of l for a pulsation of a ZZ Ceti star. We also fin…
The Nature of the Ultraviolet Continuum in Type 2 Seyfert Galaxies
Leitherer, C.; Calzetti, D.; Meurer, G. +6 more
Type 2 Seyfert nuclei are well known to contain a "featureless continuum" which makes a significant contribution in the optical and ultraviolet. However, the nature of this featureless continuum is not clear. Recent optical spectropolarimetry shows that only a minor part of the optical featureless continuum can be light from a hidden Seyfert 1 nuc…
The Massive Stars of I ZW 18 as Seen in Hubble Space Telescope Images
Hunter, Deidre A.; Thronson, Harley A., Jr.
Blue compact dwarf galaxies are tiny galaxies that are dominated by intense star-forming regions. Thus, they have been thought to represent a different and extreme environment for star formation compared to the Milky Way and many other nearby galaxies. In this paper we use images obtained with the Hubble Space Telescope to resolve the main body of…
The Hubble Space Telescope Quasar Absorption Line Key Project. V. Redshift Evolution of Lyman Limit Absorption in the Spectra of a Large Sample of Quasars
Turnshek, David A.; Schneider, Donald P.; Steidel, Charles C. +10 more
Using a sample of 119 QSOs, containing objects we have selected having previously available high quality ground-based and IUE spectral observations, together with Hubble Space Telescope (HST) observations of 26 QSOs from Bahcall et al. (1993, 1995) and Impey et al. (1995) and new optical observations of 41 objects by Steidel & Sargent (1995), …
The IUE MEGA Campaign: Wind Variability and Rotation in Early-Type Stars
Koenigsberger, G.; Howarth, I. D.; Owocki, S. P. +30 more
Wind variability in OB stars may be ubiquitous, and a connection between projected stellar rotation velocity and wind activity is well established. However, the origin of this connection is unknown. To probe the nature of the rotation connection, several of the attendees at the workshop on Instability and Variability of Hot-Star Winds drafted an I…
The Local LY alpha Forest: Association of Clouds with Superclusters and Voids
Carilli, Chris; Donahue, Megan; Shull, J. Michael +2 more
The Goddard High Resolution Spectrograph aboard the Hubble Space Telescope was used with the G160M grating to obtain high-resolution (0.2 Å) spectra of three very bright active galactic nuclei located behind voids in the nearby distribution of bright galaxies (i.e., CfA and Arecibo redshift survey regions). A total of eight definite (≥ 4 σ) Lyα ab…
Very Low Mass Stars and White Dwarfs in NGC 6397
Paresce, Francesco; de Marchi, Guido; Romaniello, Martino
Deep Wide Field/Planetary Camera 2 (WFPC2) images in wide bands centered at 606 and 802 nm were taken with the Hubble Space Telescope (HST) 4.6 min from the center of the galactic globular cluster NGC 6397. The images were used to accurately position approximately 2120 stars detected in the field on a color magnitude diagram down to a limiting mag…
The Striking Near-Infrared Morphology of the Inner Region in M100
Knapen, J. H.; Peletier, R. F.; de Jong, R. S. +3 more
New optical and near-infrared (NIR) X-band images of the inner 3 kpc region of the nearby Virgo spiral M100 (NGC 4321) display remarkable morphological changes with wavelength. While in the optical the light is dominated by a circumnuclear zone of enhanced star formation, the morphological features in the 2.2 micron image correspond to a newly dis…