scholarly journals Extreme Ultraviolet Explorer Optical Identification Campaign.III. A Southern Hemisphere Sample of Active Late-Type Stars and White Dwarfs

1997 ◽  
Vol 114 ◽  
pp. 244 ◽  
Author(s):  
Nahide Craig ◽  
Damian J. Christian ◽  
Jean Dupuis ◽  
Bryce A. Roberts
Keyword(s):  
Southern Hemisphere ◽  
White Dwarfs ◽  
Extreme Ultraviolet ◽  
Late Type ◽  
Optical Identification

Hot White Dwarfs in the Extreme Ultraviolet Explorer Survey. I. Properties of a Southern Hemisphere Sample

1996 ◽  
Vol 467 ◽  
pp. 782 ◽  
Author(s):  
Stephane Vennes ◽  
Peter A. Thejll ◽  
Dayal T. Wickramasinghe ◽  
Michael S. Bessell
Keyword(s):  
Southern Hemisphere ◽  
White Dwarfs ◽  
Extreme Ultraviolet

Faint Sources in theEUVESurvey: Identification of White Dwarfs, Active Late‐Type Stars, and Galactic Nuclei

1997 ◽  
Vol 486 (1) ◽  
pp. 179-196 ◽  
Author(s):  
Elisha Polomski ◽  
Stephane Vennes ◽  
John R. Thorstensen ◽  
Mihalis Mathioudakis ◽  
Emilio E. Falco
Keyword(s):  
White Dwarfs ◽  
Galactic Nuclei ◽  
Late Type

scholarly journals A Spectroscopic Survey in the EUV of the “Coolest” Hot DA Stars

1996 ◽  
Vol 152 ◽  
pp. 217-222
Author(s):  
Jean Dupuis ◽  
Stéphane Vennes
Keyword(s):  
Effective Temperature ◽  
White Dwarfs ◽  
Heavy Element ◽  
Extreme Ultraviolet ◽  
Diffusion Theory ◽  
Hydrogen Atmosphere ◽  
Element Abundance ◽  
Pure Hydrogen ◽  
Element Abundances ◽  
The One

We present an analysis of the extreme ultraviolet (EUV) spectroscopy of a sample of 10 DA white dwarfs observed by the Extreme Ultraviolet Explorer (EUVE). We have selected white dwarfs cooler than about 50,000 K and with presumably low heavy element abundances. The goal of this study is to determine the fundamental atmospheric parameters, namely the effective temperature and chemical composition, of these stars by fitting their continua with synthetic spectra computed from pure hydrogen LTE/line-blanketed model atmospheres. The question of the presence (or absence) of trace elements is explored by comparing EUV-determined effective temperatures to the one obtained from a fit of hydrogen balmer lines. It is found that the majority of the DA in the sample are consistent with having a pure hydrogen atmosphere. One of the star, MCT0027-634, is another possible example of a HZ 43-type white dwarf, having an effective temperature above 50000 K and a low heavy element abundance, i.e., much lower than predicted by diffusion theory.

scholarly journals Expected Scientific Performance of the Three Spectrometers on the Extreme Ultraviolet Explorer

1990 ◽  
Vol 115 ◽  
pp. 335-338
Author(s):  
J. V. Vallerga ◽  
P. Jelinsky ◽  
P. W. Vedder ◽  
R. F. Malina
Keyword(s):  
Wavelength Range ◽  
Spectral Resolution ◽  
Line Source ◽  
White Dwarfs ◽  
Extreme Ultraviolet ◽  
Cataclysmic Variables ◽  
Effective Area ◽  
Light Sources ◽  
Scientific Performance ◽  
Astronomical Satellite

AbstractThe expected in-orbit performance of the three spectrometers included on the Extreme Ultraviolet Explorer (EUVE) astronomical satellite is presented. Recent calibrations of the gratings, mirrors and detectors using monochromatic and continuum EUV light sources allow the calculation of the spectral resolution and throughput of the instrument. An effective area range of 0.2 to 2.8 cm2 is achieved over the wavelength range 70-600Å with a peak spectral resolution λ/Δλ (FWHM) of ~ 360 assuming a spacecraft pointing knowledge of 10 arc seconds (FWHM). For a 40,000 sec observation, the average 3σ sensitivity to a monochromatic line source is 3 × 103 photons cm-2 sec-1. Simulated observations of known classes of EUV sources such as hot white dwarfs and cataclysmic variables are also presented.

Optical Identification of the ROSAT All-Sky Survey Sources in Two 2° × 2° Fields

1997 ◽  
Vol 159 ◽  
pp. 427-428
Author(s):  
Y. Zhao ◽  
J. Zhong ◽  
J. Wei ◽  
J. Hu ◽  
Q. Li
Keyword(s):  
Ccd Camera ◽  
Seyfert Galaxies ◽  
Astronomical Observatory ◽  
Active Galaxies ◽  
Clusters Of Galaxies ◽  
Late Type ◽  
Optical Identification ◽  
X Ray ◽  
Sky Survey

AbstractWe used the CCD camera and spectrograph of the 2.16-m telescope of Beijing Astronomical Observatory to identify the ROSAT All-Sky survey sources in two 2° Ü 2° fields. Of a total of 16 X-ray sources, we identified 13 of them as follows: two QSOs, two Seyfert galaxies, two active galaxies, two clusters of galaxies, and five late-type stars. Three X-ray sources remained unidentified.

Faint Sources in the EUVE Survey. II. Identification of Two White Dwarfs and Four Late-Type Active Stars.

1997 ◽  
Vol 114 ◽  
pp. 1567 ◽  
Author(s):  
Stephane Vennes ◽  
Eric Korpela ◽  
Stuart Bowyer
Keyword(s):  
White Dwarfs ◽  
Late Type ◽  
Active Stars
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