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| Paper: |
On the Red Edge of the GW Virginis Instability Strip |
| Volume: |
135, A Half Century of Stellar Pulsation Interpretations: a Tribute to Arthur N. Cox |
| Page: |
130 |
| Authors: |
Werner, K.; Dreizler, S.; Heber, U.; Rauch, T. |
| Abstract: |
GW Vir (alias PG1159-035) is the prototype of a spectroscopic class of extremely hot hydrogen-deficient (pre-) White Dwarfs. The prototype as well as a number of other PG1159 stars define the GW Vir (or DOV) instability strip in the HR diagram. Considerable effort has been made to confine the limits of this instability strip by both, pulsational theory (Kawaler and collaborators) as well as by spectroscopic analysis (Werner and collaborators). Our first analysis of the prototype (Werner, Heber, Hunger 1991 A&A 244, 437) revealed the peculiar surface abundances which entered as an essential ingredient into the pulsational analysis of Whole Earth Telescope (WET) observations (Kawaler & Bradley 1994, ApJ 427, 415). We succeeded in constraining the blue edge of the instability strip (Werner et al. 1996, IAU Coll. 155, p. 96). We now present non-LTE model atmosphere analyses of RcoolS (Teff < 100,000K) PG1159 stars based on latest UV spectra obtained with the Hubble Space Telescope, aiming at the red edge of the instability strip. Preliminary results indicate that the red edge is much less well defined and seems to depend rather sensitively on photospheric and stellar parameters. The analysis comprises one pulsator which was a target of a WET observation run and it will support the interpretation of asteroseismologic analyses. |
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