Search Publications
The Mass Accretion Rates of Intermediate-Mass T Tauri Stars
Gordon, Karl D.; Hartmann, Lee; Calvet, Nuria +4 more
We present Hubble Space Telescope ultraviolet spectra and supporting ground-based data for a sample of nine intermediate-mass T Tauri stars (IMTTSs; 1.5-4 Msolar). The targets belong to three star-forming regions: T Tau, SU Aur, and RY Tau in the Taurus clouds; EZ Ori, P2441, and V1044 Ori in the Ori OB1c association surrounding the Ori…
The jets and supercritical accretion disk in SS433
Fabrika, S.
The review describes observations and investigations of the unique object SS433 obtained after 23 years of studying this massive binary system. The main difference between SS433 and other known X-ray binaries is the action of a constant supercritical regime for the accretion of gas onto the relativistic star (most likely a black hole), which has l…
Star formation history and dust content of galaxies drawn from ultraviolet surveys
Kong, X.; Brinchmann, J.; Charlot, S. +1 more
We compile a new sample of 115 nearby, non-Seyfert galaxies spanning a wide range of star formation activities, from starburst to nearly dormant, based on ultraviolet observations with various satellites. We combine these observations with infrared observations to study the relation between ratio of total far-infrared to ultraviolet luminosity and…
Grids of model spectra for WN stars, ready for use
Hamann, W. -R.; Gräfener, G.
Grids of model atmospheres for Wolf-Rayet stars of the nitrogen sequence (WN subclass) are presented. The calculations account for the expansion of the atmosphere, non-LTE, clumping, and line blanketing from iron-group elements. Observed spectra of single Galactic WN stars can in general be reproduced consistently by this generation of models. The…
Hubble Space Telescope Absolute Spectrophotometry of Vega from the Far-Ultraviolet to the Infrared
Bohlin, R. C.; Gilliland, R. L.
The Space Telescope Imaging Spectrograph (STIS) has measured the absolute flux for Vega from 0.17-1.01 µm on the Hubble Space Telescope white dwarf (WD) flux scale. These data are saturated by up to a factor of 80 overexposure but retain linearity to a precision of 0.2% because the charge bleeds along the columns and is recovered during read…
Ultraviolet Extinction Properties in the Milky Way
Gordon, Karl D.; Clayton, Geoffrey C.; Valencic, Lynne A.
We have assembled a homogeneous database of 417 ultraviolet (UV) extinction curves for reddened sight lines having International Ultraviolet Explorer spectra. We have combined these with optical and Two Micron All Sky Survey photometry, allowing estimates of the ratio of total-to-selective extinction, RV, for the entire sample. Fitzpatr…
Bright OB stars in the Galaxy. I. Mass-loss and wind-momentum rates of O-type stars: A pure H\alpha analysis accounting for line-blanketing
Puls, J.; Markov, H.; Markova, N. +1 more
We study mass-loss and wind momentum rates of 29 Galactic O-type stars with luminosity classes I, III and V by means of a pure H\alpha profile analysis and investigate to what extent the results compare to those originating from a state-of-the-art, complete spectral analysis. Our investigation relies on the approximate method developed by \citet{P…
Indications of a Large Fraction of Spectroscopic Binaries among Nuclei of Planetary Nebulae
Bond, Howard E.; De Marco, Orsola; Harmer, Dianne +1 more
Previous work indicates that about 10% of planetary-nebula nuclei (PNNi) are photometrically variable short-period binaries with periods of hours to a few days. These systems have most likely descended from common-envelope (CE) interactions in initially much wider binaries. Population-synthesis studies suggest that these very close pairs could be …
Study of the properties and spectral energy distributions of the Herbig AeBe stars HD 34282 and HD 141569
Rauer, H.; Schneider, J.; Eiroa, C. +21 more
We present a study of the stellar parameters, distances and spectral energy distributions (SEDs) of
On the origin of the C IV Baldwin effect in active galactic nuclei
Laor, Ari; Baskin, Alexei
The origin of the luminosity dependence of the equivalent width (EW) of broad emission lines in active galactic nuclei (AGN) - the Baldwin effect - is not firmly established yet. We explore this question for the broad C IVλ1549 line using the Boroson & Green sample of the 87 z<= 0.5 Bright Quasar Survey (BQS) quasars. Useful UV spectra of t…