The temperature scale of hot DA white dwarfs - Temperatures from far-ultraviolet continuum fluxes

1990 ◽  
Vol 359 ◽  
pp. 483 ◽  
Author(s):  
David S. Finley ◽  
Gibor Basri ◽  
Stuart Bowyer
Keyword(s):  
White Dwarfs ◽  
Temperature Scale ◽  
Ultraviolet Continuum ◽  
Far Ultraviolet

The Temperature Scale and Mass Distribution of Hot DA White Dwarfs

1997 ◽  
Vol 488 (1) ◽  
pp. 375-396 ◽  
Author(s):  
David S. Finley ◽  
Detlev Koester ◽  
Gibor Basri
Keyword(s):  
Mass Distribution ◽  
White Dwarfs ◽  
Temperature Scale

scholarly journals FAR-Ultralviolet Spectrophotometry of two do White Dwarfs from Voyager

1989 ◽  
Vol 114 ◽  
pp. 144-148
Author(s):  
E. Poulin ◽  
F. Wesemael ◽  
J.B. Holberg ◽  
G. Fontaine
Keyword(s):  
Binary System ◽  
White Dwarfs ◽  
Temperature Scale ◽  
Classification Scheme ◽  
The Other ◽  
Other Hand ◽  
Effective Temperatures

While the observed number of hot, helium-rich degenerates is noticeably larger than that of their hydrogen-rich counterparts, the calibration of their effective temperatures has been comparatively much less trustworthy. The spectroscopic classification scheme introduced three years ago by Wesemael, Green, and Liebert (1985, hereafter WGL), and the crude temperature domains associated with each class remain, to this date, the only comprehensive effort at defining a temperature scale for DO stars. The current uncertainty in this is perhaps best epitomized by two objects, HD149499B and PG1034+001. The former belongs to a binary system which also contains a KO V primary, 2” away. The temperature determined for the degenerate secondary ranges from 85,000±15,000 K (Wray, Parsons, and Henize 1979) to 55,000±5000 K (Sion, Guinan, and Wesemael 1982, hereafter SGW). PG1034+001, on the other hand, is the prototype of the so-called hot DO spectroscopic class; WGL assign an uncertain temperature of 80,000±20,000 K to this object.

The origin of the far-ultraviolet continuum in solar and stellar flares

1992 ◽  
Vol 385 ◽  
pp. 731 ◽  
Author(s):  
K. J. H. Phillips ◽  
G. E. Bromage ◽  
J. G. Doyle
Keyword(s):  
Ultraviolet Continuum ◽  
Stellar Flares ◽  
Far Ultraviolet

Voyager Observations of Diffuse Far-Ultraviolet Continuum and Line Emission in Eridanus

1993 ◽  
Vol 419 ◽  
pp. 739 ◽  
Author(s):  
Jayant Murthy ◽  
M. Im ◽  
R. C. Henry ◽  
J. B. Holberg
Keyword(s):  
Line Emission ◽  
Ultraviolet Continuum ◽  
Far Ultraviolet

scholarly journals GALEX absolute calibration and extinction coefficients based on white dwarfs

2019 ◽  
Vol 489 (4) ◽  
pp. 5046-5052 ◽  
Author(s):  
Renae E Wall ◽  
Mukremin Kilic ◽  
P Bergeron ◽  
B Rolland ◽  
C Genest-Beaulieu ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
White Dwarfs ◽  
Signal To Noise Ratio ◽  
Model Atmosphere ◽  
Absolute Calibration ◽  
High Signal ◽  
Extinction Coefficients ◽  
Near Ultraviolet ◽  
The Galaxy ◽  
Far Ultraviolet

ABSTRACT We use 1837 DA white dwarfs with high signal-to-noise ratio spectra and Gaia parallaxes to verify the absolute calibration and extinction coefficients for the Galaxy Evolution Explorer (GALEX). We use white dwarfs within 100 pc to verify the linearity correction to the GALEX data. We find that the linearity correction is valid for magnitudes brighter than 15.95 and 16.95 for the far-ultraviolet (FUV) and near-ultraviolet (NUV) bands, respectively. We also use DA white dwarfs beyond 250 pc to calculate extinction coefficients in the FUV and NUV bands: RFUV = 8.01 ± 0.07 and RNUV = 6.72 ± 0.04. These are consistent with the predicted extinction coefficients for Milky Way-type dust in the FUV, but smaller than predictions in the NUV. With well understood optical spectra and state-of-the-art model atmosphere analysis, these white dwarfs currently provide the best constraints on the extinction coefficients for the GALEX data.

scholarly journals FAR-ULTRAVIOLET CONTINUUM EMISSION: APPLYING THIS DIAGNOSTIC TO THE CHROMOSPHERES OF SOLAR-MASS STARS

2011 ◽  
Vol 745 (1) ◽  
pp. 25 ◽  
Author(s):  
Jeffrey L. Linsky ◽  
Rachel Bushinsky ◽  
Tom Ayres ◽  
Juan Fontenla ◽  
Kevin France
Keyword(s):  
Continuum Emission ◽  
Ultraviolet Continuum ◽  
Solar Mass ◽  
Far Ultraviolet

scholarly journals A far-UV survey of three hot, metal-polluted white dwarf stars: WD0455−282, WD0621−376, and WD2211−495

2019 ◽  
Vol 487 (3) ◽  
pp. 3470-3487 ◽  
Author(s):  
Simon P Preval ◽  
Martin A Barstow ◽  
Matthew Bainbridge ◽  
Nicole Reindl ◽  
Thomas Ayres ◽  
...  
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Hubble Space Telescope ◽  
Line Of Sight ◽  
Hot Metal ◽  
Dwarf Stars ◽  
High Resolution Data ◽  
White Dwarf Stars ◽  
Order Of Magnitude ◽  
Far Ultraviolet

ABSTRACT Using newly obtained high-resolution data (R ∼ 1 × 105) from the Hubble Space Telescope, and archival UV data from the Far Ultraviolet Spectroscopic Explorer, we have conducted a detailed UV survey of the three hot, metal-polluted white dwarfs WD0455−282, WD0621−376, and WD2211−495. Using bespoke model atmospheres, we measured Teff, log g, and photospheric abundances for these stars. In conjunction with data from Gaia, we measured masses, radii, and gravitational redshift velocities for our sample of objects. We compared the measured photospheric abundances with those predicted by radiative levitation theory, and found that the observed Si abundances in all three white dwarfs, and the observed Fe abundances in WD0621−376 and WD2211−495, were larger than those predicted by an order of magnitude. These findings imply not only an external origin for the metals, but also ongoing accretion, as the metals not supported by radiative levitation would sink on extremely short time-scales. We measured the radial velocities of several absorption features along the line of sight to the three objects in our sample, allowing us to determine the velocities of the photospheric and interstellar components along the line of sight for each star. Interestingly, we made detections of circumstellar absorption along the line of sight to WD0455−282 with three velocity components. To our knowledge, this is the first such detection of multicomponent circumstellar absorption along the line of sight to a white dwarf.

Far-ultraviolet spectrophotometry of two do white dwarfs from Voyager

1989 ◽  
pp. 144-148 ◽  
Author(s):  
E. Poulin ◽  
F. Vesemael ◽  
J. B. Holbera ◽  
G. Fontaine
Keyword(s):  
White Dwarfs ◽  
Ultraviolet Spectrophotometry ◽  
Far Ultraviolet

scholarly journals OBSERVATION OF THE FAR-ULTRAVIOLET CONTINUUM BACKGROUND WITH SPEAR/FIMS

2011 ◽  
Vol 196 (2) ◽  
pp. 15 ◽  
Author(s):  
Kwang-Il Seon ◽  
Jerry Edelstein ◽  
Eric Korpela ◽  
Adolf Witt ◽  
Kyoung-Wook Min ◽  
...  
Keyword(s):  
Ultraviolet Continuum ◽  
Far Ultraviolet

scholarly journals Far Ultraviolet Observations of Hot DA White Dwarfs

1989 ◽  
Vol 114 ◽  
pp. 139-143 ◽  
Author(s):  
David Finley ◽  
Gibor Basri ◽  
Stuart Bowyer
Keyword(s):  
Wavelength Range ◽  
White Dwarfs ◽  
Time Dependent ◽  
Flux Correction ◽  
V Band ◽  
International Ultraviolet Explorer ◽  
Effective Temperatures ◽  
Far Ultraviolet ◽  
Ultraviolet Observations ◽  
Flux Calibration

AbstractFar ultraviolet (FUV) fluxes have been used for determining the effective temperatures of a number of DA white dwarfs hotter than 20,000 K. The spectra were obtained with the International Ultraviolet Explorer (IUE). The analysis consisted of comparing the observed FUV fluxes with model fluxes scaled to the V-band flux. After suitable corrections were performed for the time-dependent sensitivity degradation of the IUE, it was found that the available flux calibrations for the IUE were insufficiently accurate for precise temperature determinations. Accordingly, we used seven white dwarfs for which accurate, independent temperature determinations have been made from line profile analyses to improve the accuracy of the IUE flux calibration. The correction to the original calibration was as great as 20% in individual 5-Å wavelength bins, while the average over the IUE wavelength range was 5%. We present both our IUE flux correction and the temperatures obtained for the hot white dwarfs.

Sign in / Sign up

Export Citation Format

Share Document