Mode Identification of Pulsating White Dwarfs Using the Hubbl E Space T El Escope1
نویسندگان
چکیده
We have obtained time-resolved ultraviolet spectroscopy for the pulsating DAV stars G226-29 and G185-32 and for the pulsating DBV star PG 1351]489 with the Hubble Space T elescope Faint Object Spectrograph to compare the ultraviolet to the optical pulsation amplitude and determine the pulsation indices. We Ðnd that for essentially all observed pulsation modes, the amplitude rises to the ultraviolet as the theoretical models predict for l\ 1 nonradial g-modes. We do not Ðnd any pulsation mode visible only in the ultraviolet, nor any modes whose phase Ñips by 180¡ in the ultraviolet, as would be expected if high l pulsations were excited. We Ðnd one periodicity in the light curve of G185-32, at 141 s, which does not Ðt theoretical models for the change of amplitude with wavelength of g-mode pulsations. Subject headings : stars : individual (G226-29, G185-32, PG 1351]489) È stars : oscillations È stars : variables : other È ultraviolet : stars È white dwarfs
منابع مشابه
Limits on the Spatial Extent of Active Galactic Nuclei Measured with the Fine Guidance Sensors of the Hubbl E Space T El Escope1
The optical structures of several active galactic nuclei (AGNs) have been studied using the Ðne guidance sensors (FGSs) on the Hubble Space Telescope (HST ). The FGSs are interferometric devices that can resolve structure on scales of 20 mas or less and hence have the potential to improve on the resolution attainable by HST Ïs cameras. The FGSs produce interferometric fringes known as S curves,...
متن کاملThe gravitational wave radiation of pulsating white dwarfs revisited : the case of BPM 37093 and PG 1159 - 035
We compute the emission of gravitational radiation from pulsating white dwarfs. This is done by using an up-to-date stellar evolutionary code coupled with a state-of-the-art pulsational code. The emission of gravitational waves is computed for a standard 0.6M⊙ white dwarf with a liquid carbon-oxygen core and a hydrogen-rich envelope, for a massive DA white dwarf with a partially crystallized co...
متن کاملMight Carbon - Atmosphere White Dwarfs Harbour a New Type of Pulsating Star ?
Aims. In the light of the recent and unexpected discovery of a brand new type of white dwarfs, those with carbon-dominated atmospheres, we examine the asteroseismological potential of such stars. The motivation behind this is based on the observation that past models of carbon-atmosphere white dwarfs have partially ionized outer layers that bear strong resemblance with those responsible for mod...
متن کاملThe Spectral Variability of Pulsating Stars : PG 1159 - 035
With 10m class telescopes as well as with time-tagging detectors on board of HST and FUSE, the analysis of time-resolved spectra for pulsating white dwarfs becomes feasible. We present simulated time-resolved spectra for the hot pulsating white dwarf PG 1159-035 and compare these models with observational data of the 516 s mode based on HST-STIS spectroscopy. A determination of the pulsation mo...
متن کامل