Rate of change of the pulsation periods in the PG 1159 star PG 0122+200
نویسندگان
چکیده
منابع مشابه
The first PG 1159 close binary system
The archival spectrum of SDSS J212531.92-010745.9 shows not only the typical signature of a PG 1159 star, but also indicates the presence of a companion. With time-series photometry of SDSS J212531.92-010745.9 during 10 nights, spread over one month, with the Tübingen 80 cm and the Göttingen 50 cm telescopes, the binary nature of this object has recently been proven. An orbital period of 6.9 h ...
متن کاملThe pulsation modes of the pre - white dwarf PG 1159 - 035
Context. PG 1159-035, a pre-white dwarf with Teff ≃ 140 000 K, is the prototype of both two classes: the PG 1159 spectroscopic class and the DOV pulsating class. Previous studies of PG 1159-035 photometric data obtained with the Whole Earth Telescope (WET) showed a rich frequency spectrum allowing the identification of 122 pulsation modes. Analyzing the periods of pulsation, it is possible to m...
متن کاملABELL 43 , a second pulsating “ hybrid - PG 1159 ” star ⋆
An abstract should be given e report observations of the planetary nebula nucleus Abell 43, obtained at the 2.5m Nordic Optical Telescope, which show that it is a pulsator. Abell 43, a " hybrid-PG 1159 " type star, is the second pulsator of this class, after HS 2324+3944. From the limited data set acquired, we find that Abell 43 exhibits at least two periods of 2600 s and 3035 s, the longest on...
متن کاملSoft X - ray Spectroscopy of the Hot DA White Dwarf LB 1919 and the PG 1159 Star PG 1520 + 525
We have performed soft X-ray spectroscopy of two hot white dwarfs with the Chandra observatory using the Low Energy Transmission Grating. The first target is the hot DA white dwarf LB1919 (T eff =69 000 K). This star is representative of a small group of hot DAs whose metallicities lie well below predictions from radiative levitation theory. The Chandra spectrum shows a rich absorption line spe...
متن کاملThe Nature of the Driving Mechanism in the Pulsating Hybrid PG 1159 Star Abell 43
We extend our previous pulsational stability analyses of PG 1159 stars by modeling the hybrid PG 1159 type star Abell 43. We show that the standard κ-mechanism due to the ionization of C and O in the envelope of this H-rich PG 1159 star is perfectly able to drive g-mode pulsations. Thus, contrary to a recent suggestion, there is no need to invoke any new or exotic mechanism to explain the pulsa...
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ژورنال
عنوان ژورنال: Proceedings of the International Astronomical Union
سال: 2008
ISSN: 1743-9213,1743-9221
DOI: 10.1017/s1743921308022709