Search Publications
Missions
Journals
Publication Years
Hubble Space Telescope Far-Ultraviolet Imaging of M31, M32, and NGC 205
Bressan, A.; di Serego Alighieri, S.; Buson, L. M. +3 more
Hubble Space Telescope Faint Object Camera (FOC) f/48 images of M31, M32, and NGC 205 (field of view 23" x 23" with 0.45" pixel size) are analyzed as observed through the combined UV filters F150W and F130LP. The absolute calibration of the data and the internal disagreement between observed and expected count rates in the UV region lead us to sug…
Discovery of a galactic supersoft binary X-ray source.
Burwitz, V.; Beuermann, K.; de Martino, D. +10 more
We report the discovery of the galactic very soft ('supersoft') X-ray source RXJ0019.8+2156 and its 12.2mag optical counterpart. The system displays quasi-sinusoidal modulations of the optical, UV, and X-ray light curves as well as regular radial-velocity variations with a 15.85 hour period which we interpret as the binary orbital period. The syst…
Gas and dust emission from a dusty porous comet.
Capaccioni, F.; Orosei, R.; Coradini, A. +5 more
A comet nucleus is a porous aggregate of ices and dust in which solar heating causes the sublimation of volatiles and the ejection of dust particles lifted by the flow of the escaping gases. We present a numerical model that solves the heat conduction and the gas diffusion equations throughout a porous comet nucleus made of H_2_O ice, CO_2_ ice an…
The Active Phase of the Hot Component of Z Andromedae
Gonzalez-Riestra, R.; Seaquist, E. R.; Cassatella, A. +2 more
Z And is considered the prototype of the symbolic class. Quiescence data show that its hot component lies close to the central stars of planetary nebulae in the H-R diagram. This system underwent an outburst at the beginning of 1984. The activity phase lasted for approximately 900 days with two maxima in 1984 April and 1985 December. In this work …
An HST Archival Study of Galactic Interstellar Zinc and Chromium
Roth, Katherine C.; Blades, J. Chris
We present a survey of interstellar Zn II and Cr II absorption extracted from the Hubble Space Telescope Goddard High Resolution Spectrograph (HST GHRS) data archive. We find clear evidence for an enhanced depletion of Zn from the gas phase with increasing fractional abundance of molecular hydrogen f(H2). Our lower limit to the Galactic interstell…
Scattering Properties of the Dust in the Reflection Nebula IC 435
Gordon, Karl D.; Calzetti, Daniela; Bianchi, Luciana +2 more
New lUE observations of the reflection nebula IC 435 are presented, and the scattering properties of the nebular dust grains are derived. Previous studies of this nebula suggested the presence of enhanced scattering in the 2175 Å interstellar extinction bump, which the new data do not confirm. The UV observations plus optical data from the literat…
Far-UV Properties of the Nuclear Region of M31
King, Ivan R.; Stanford, S. Adam; Crane, Philippe
Comparison of the HST far-UV and visible images of the nucleus of M31 deepens the mystery of the two brightness peaks recently discovered by Lauer et al. (AJ, 106,1436(1993)]. At 175 nm the brightest point is the optically fainter peak (P2) that is close to the dynamical center. The very center of P2 has a UV upturn that is much greater than that …
HST/GHRS Observations of the beta Pictoris System: Basic Parameters of the Age of the System
Hubeny, Ivan; Heap, Sara R.; Lanz, Thierry
We have reevaluated the basic parameters and age of the A5 IV--V star, beta Pictoris, making use of new observations obtained by the Goddard High-Resolution Spectrograph aboard the Hubble Space Telescope and using modern methods of atmospheric modeling and spectral synthesis. We derive stellar parameters appropriate to its spectral type (Teff = 82…
Detectability and incidence of E+A galaxies in the distant cluster Cl0939+472 (z=0.41).
Belloni, P.; Bruzual, A. G.; Thimm, G. J. +1 more
We present results of a study of E+A galaxies in the cluster Cl0939+472 (z=0.41). We have used a series of narrow-band filters (FWHM=~90-200A) covering the range from 3800 to 9200A, and broad band B, R, I filters to obtain low resolution spectra for all galaxies brighter than R=22.5mag in a 5x5' cluster field. Two of the narrow-band filters have b…
The Incidence of Damped LY alpha Systems in the Redshift Interval 0 < Z < 4
Turnshek, David A.; Rao, Sandhya M.; Briggs, Franklin H.
The determination of the incidence and column density distribution of damped Lyα systems from QSO absorption-line surveys in the redshift interval 0 < z < 1.65 is crucial for constraining the evolution of neutral gas in galaxies. This redshift interval corresponds to a time interval of ∼62% of the age of the universe for q0 = 0 (7…