Ongoing Mass Ejection in the Peculiar, Hot Do Degenerate KPD 0005+5106
Abstract
We present an analysis of four high-resolution far-ultraviolet spectra of the hot, peculiar DO white dwarf KPD 0005+5106 obtained with short-wavelength prime (SWP) spectrograph aboard the International Ultraviolet Explorer (lUE) spacecraft. These spectra reveal weak, probably variable, peculiar absorption and emission transitions of ultrahigh excitation C V and N V in the 1615-1623 Å region, 0 VIII variable coronal emission, variable line structure at Re II (1640), and essentially constant photospheric/circumstellar/ interstellar blended N V, Si IV, and C IV resonance absorption. Our four lUE echelle spectra confirm the high excitation C IV absorption feature at 1230.55 Å but reveal little evidence of the high excitation C IV features at 1351 and 1353 Å seen most strongly in the PG 1159 degenerates. Moreover, high excitation 0 vi and C IV transitions are at most very minor contributors to the broad absorption at 1640 Å. We find distinct evidence of a moderately dense neutral cloud along the line of sight to KPD 0005. This cloud, if near the white dwarf, may interact with the stellar wind to produce a zone of shock-induced high ionization. The nonphotospheric interstellar/circumstellar components of the N V resonance doublet in KPD 0005 yield a column density log N (N v)= 13.8, a factor of 8-10 higher than the value which might be expected from the diffuse ISM. The nonphotospheric components of N V in the PG 1159 object RXJ 2117+3412 have a similar velocity (50 km/s) relative to the photospheric rest frame and are markedly stronger. Both objects exhibit strong O VIII emission, a possible marker of mass loss. These characteristics providing compelling evidence that the nonphotospheric N V absorption is locally associated with these two hot degenerates and almost certainly ejected.
- Publication:
-
The Astronomical Journal
- Pub Date:
- January 1997
- DOI:
- 10.1086/118259
- Bibcode:
- 1997AJ....113..364S
- Keywords:
-
- WHITE DWARFS;
- STARS: INDIVIDUAL: KPD 0005+5106