Search Publications
Highly Ionized Stellar Winds in Be Stars. II. Winds in B6--B9.5e Stars
Shore, Steven N.; Sonneborn, George; Grady, C. A. +3 more
The results of a UV survey of stellar winds and circumstellar shells in 40 B6-B9.5e stars covering luminosity classes V-III are presented. A graph is presented of the region from 1520-1560 A, which includes both the Si II UV multiplet 2 transitions and the C IV resonance transition for selected Be stars in the sample. The detection of shortward-sh…
A 2597 : another massive cooling flow.
Fabian, A. C.; Johnstone, R. M.; Crawford, C. S. +1 more
We present X-ray, optical and ultraviolet observations of the rich cluster A2597 and confirm the presence of a central cooling flow. The intracluster gas is cooling at a rate of ~370 M_sun_ yr^-1^ and we observe extended optical line-emitting gas around the central galaxy over a radial distance of ~25 kpc. Examination of the blue continuum spectru…
A Case Study of a WC Planetary Nebula Nucleus: Henize 2-99
Feibelman, Walter A.; Shaw, Richard A.; Lutz, Julie H. +1 more
The WC spectrum of the nucleus of the planetary nebula Henize 2-99. Fluxes are given, emission lines are identified, and blends are described. The most powerful emissions are C III, C II, and C IV. O, H, and Si lines are also observed, but little stellar nitrogen is found except for N V. The interstellar extinction is estimated at c = 0.9 + or - 0…
X-ray spectroscopy of RS CVn stars with EXOSAT.
Schmitt, J. H. M. M.; Pasquini, L.; Pallavicini, R.
Results are presented of a spectral analysis of a sample of RS CVn stars which comprises all (except two) cataloged RS CVn binaries observed by Exosat. Data from both the Medium Energy and Low Energy Exosat experiments are analyzed assuming simple spectral models and the dependence of the fitted coronal parameters on the signal-to-noise ratio. Evi…
Ultraviolet P-Cygni profile variations in HD 50896.
Howarth, I. D.; Willis, A. J.; Smith, L. J. +2 more
An analysis of 68 high-resolution IUE UV spectra of HD 50896 obtained at 9 separate epochs during the 1978-1983 period is presented. No evidence is found for the presence of a neutron star companion, and it is suggested that the observed UV profile variations are due to changes which are intrinsic to the WN5 stellar wind. The 46 spectra obtained d…
IUE observations of the M dwarfs CM Draconis and Rossiter 137B : magnetic activity at saturated levels.
Linsky, J. L.; Vilhu, O.; Neff, J. E. +4 more
IUE observations of two active M dwarfs with known rotation rate or age and presumed to be almost totally convective are presented. The first of these stars, CM Draconis (Gl 630.1), is an old Population II binary with its components in tidally induced rapid rotation (P = 1.27 d, dM 4 + dM 4). The other one, Rossiter 137 B, forms with HD 36705 (AB …
On the Size Distribution of Newly Formed Grains in Red Supergiant Atmospheres
Snow, Theodore P.; Seab, C. Gregory
Theoretical ultraviolet extinction curves have been calculated for comparison with observed curves for circumstellar dust in M supergiants. The theoretical curves assume a silicate grain composition, because silicate grains are expected in the oxygen-rich environments that are observed. Calculations were performed with and without the inclusion of…
The distance of the helium-variable B star HD 37479.
Heber, U.; Groote, D.; Hunger, K.
The gravity of HD 37479 (Sigma Ori E) is redetermined using eight high resolution and high S/N ratio spectrograms. The analysis is carried out differentially with respect to the main sequence stars Gamma Peg and Sigma Ori D. It is confirmed that the gravity of HD 37479 is log g = 3.95 + or - 0.15. Evidence is presented for a peculiar interstellar …
The Peculiar Planetary Nebula in M22
Cohen, J. G.; Gillett, F. C.
The source discovered by the IRAS satellite near the center of the globular cluster M22, IRAS 18333-2357, has been studied using the IUE satellite and a ground-based optical telescope. The northern component of the close pair of stars is not a member of the cluster. The southern component is a hot star with T(eff) of about 50,000 K illuminating a …
A 4.1 keV spectral feature in a type 1 X-ray burst from EXO 1747-214.
van Paradijs, J.; Lewin, W. H. G.; Magnier, E. +3 more
We present the results of a spectral analysis of two type 1 bursts from EXO 1747-214 detected during 9.4 h of observing with EXOSAT. The spectrum, during the rise of the strongest burst, shows a spectral feature, which can be well represented by an absorption line at 4.05 +/- 0.1 keV; the line has an equivalent width of 570 +/- 87 eV; the upper li…