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Mode Identification of BPM 37093 with the HST
Kepler, S. O.; Montgomery, M. H.; Winget, D. E. +3 more
Theoretical calculations indicate that the massive pulsating white dwarf BPM 37093 has a crystallized interior (Winget et al. 1997, Kanaan 1996, Montgomery 1998). Crystallization was predicted theoretically about 40 years ago (Abrisokov 1961, Kirshnitz 1960; Salpeter 1961), but in spite of its importance in astrophysics, there is no direct observa…
Mode Identification in Pulsating White Dwarfs Using the HST
Kepler, S. O.; Clemens, J. C.; Jiang, X. J. +3 more
We obtained time-resolved ultraviolet spectroscopy for the pulsating DA stars G 226-29 and G 185-32 and for the pulsating DBV star PG 1351+489 with the Hubble Space Telescope Faint Object Spectrograph, to compare the ultraviolet to the optical pulsation amplitudes. We find that for essentially all observed pulsation modes the amplitude rises to th…
MASCOT: A Multi-Wavelength All-Sky Catalogue for Observations With Ground- and Space-Based Telescopes
Pasian, F.; Dluzhnevskaya, O.; Malkov, O.
New powerful observational techniques require a careful planning of observing programs. These requirements will be met within the proposed project MASCOT, A Multi-wavelength All-Sky Catalogue for Observations with ground- and space-based Telescopes. MASCOT will be based on the world's largest digitized all-sky survey containing astrometric and pho…
An IUE Archival Study of the White Dwarf Temperature Variation in the Dwarf Nova WZ Sagittae
Sion, E. M.; Cheng, F. H.; Slevinsky, R. J. +2 more
The IUE archive offers a series of far UV spectra of ultra-short period dwarf nova WZ Sge over a long time baseline and hence the opportunity to monitor the ongoing accretion, the cooling of the white dwarf and temporal variations in the line spectra. We have carried out a quantitative analysis of these spectra including model atmosphere simulatio…
The Temperature of the Hot DB GD 190
Provencal, J. L.; Shipman, H. L.
We are currently in the midst of an investigation of hydrogen and carbon abundances in hot DB white dwarfs. Our HST UV spectra give evidence that hot DBs contain traces of carbon which can be used to determine the temperatures of these objects. We present the results of our investigation of GD 190.
Radial Velocities of Population II Stars. II.
Bartkevičius, A.; Sperauskas, J.
A program for radial velocity measurements of Population II stars was started in 1988 and was carried out during six observing runs. The program includes metal-deficient stars, components of Population II visual binaries or common proper motion stars, suspected radial velocity variables and the Population II stars from the Hipparcos program. The m…
Photoelectric Vilnius Photometry of Hipparcos Turn-Off Region Stars
Ezhkova, O. V.; Lazauskaite, R.; Bartasiute, S.
Seven-color photometry in the Vilnius system and photometric classification in terms of spectral type, absolute magnitude and metallicity are presented for 145 Hipparcos stars of the turn-off region, most of which have parallaxes determined to an accuracy of at least 15%. The stars selected for the observing program included those identified kinem…
HST Spectroscopy of PG 1159 Stars: the Boundary of the GW VIR Instability Strip
Dreizler, S.
Our recent analysis of PG 1159 stars, mainly based on the HST spectroscopy, is presented. The results allow several conclusions regarding the boundary of the GW Vir instability strip and the driving mechanism for these pulsations.
HST Observation of GD 358
Kepler, S. O.; Winget, D. E.; Koester, D. +5 more
The success of asteroseismology lies in the correct identification of the star's normal modes of oscillation. Winget et al. (1994) identified the normal modes of a helium white dwarf pulsator, GD 358, through the frequency distribution of the pulsation. Robinson et al. (1995) described a new mode identification method by comparing the pulsation am…
Photometry from the HIPPARCOS Catalogue: Constant MCP Stars, Comparison and Check Stars
Adelman, S. J.
Photometry from the Hipparcos catalogue is used to verify the constancy of four magnetic CP stars, as well as the comparison and the check stars used for variability studies of normal and chemically peculiar B and A stars with the Four College Automated Photoelectric Telescope; variability in these stars can produce spurious results. A few of the …