Amplitude and frequency variability of the pulsating DB white dwarf stars KUV 05134+2605 and PG 1654+160 observed with the Whole Earth Telescope

This group of stars consists of 4 systems, also called helium cataclysmics. Three of them show photometric variations and have been studied by the Whole Earth Telescope (WET), which have revealed multiperiodic light curves showing the signature of g-mode non-radial pulsations on the accreting star. The combination of accretion and g-mode pulsations gives a unique opportunity to test models for the accreator's structural changes in response to accretion. IUE-spectra provide additional physical parameters.

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Asteroseismology of White Dwarf Stars with the Whole Earth Telescope

White Dwarfs ◽

10.1007/978-94-011-3230-5_13 ◽

1991 ◽

pp. 129-141 ◽

Cited By ~ 3

Author(s):

D. E. Winget

Keyword(s):

White Dwarf ◽

Dwarf Stars ◽

White Dwarf Stars ◽

Whole Earth

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The Whole Earth Telescope

International Astronomical Union Colloquium ◽

10.1017/s0252921100099371 ◽

1989 ◽

Vol 114 ◽

pp. 109-114 ◽

Cited By ~ 1

Author(s):

R. Edward Nather

Keyword(s):

Star Formation ◽

Light Curve ◽

Early Universe ◽

White Dwarf ◽

Dwarf Stars ◽

Detailed History ◽

White Dwarf Stars ◽

Observational Technique ◽

History Of ◽

Whole Earth

AbstractThe history of our galaxy and the detailed history of star formation in the early universe is written in the white dwarf stars. Recently we have learned how to reach beneath their exposed surfaces by observing white dwarfs that are intrinsic variables. We use the stellar equivalent of seismology to probe their interiors, and thus to unravel the history they hold inside. We have designed and placed into operation an observational technique that uses the whole earth as a telescope platform, defeating the effects of daylight which, until now, had seriously limited the length of a single light curve, and therefore the amount of information we could hope to extract from it. This paper describes our new telescope and presents preliminary results from our first observing run in March, 1988.

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White Dwarf.Org - Establishing a Permanent Endowment for the Whole Earth Telescope

Open Astronomy ◽

10.1515/astro-2017-0053 ◽

2003 ◽

Vol 12 (2) ◽

Author(s):

Travis S. Metcalfe

Keyword(s):

White Dwarf ◽

Fund Raising ◽

Current Status ◽

Dwarf Stars ◽

Non Profit ◽

White Dwarf Stars ◽

Funding Sources ◽

Governmental Funding ◽

Whole Earth

AbstractWhite Dwarf Research Corporation is a non-profit organization dedicated to scientific research and public education on topics relevant to white dwarf stars. It was founded in 1999 in Austin, Texas to help fulfill the need for an alternative research center where scarce funding dollars could be used more efficiently, and to provide a direct link between astronomers who study white dwarf stars and the general public. Due to its administrative simplicity, WDRC can facilitate the funding of multi-institutional and international collaborations, provide seamless grant portability, minimize overhead rates, and actively seek non-governmental funding sources. I describe the motivation for, and current status of, one of the long-term goals of WDRC: to establish a permanent endowment for the operation of the Whole Earth Telescope. I pay particular attention to fund-raising efforts through the website at http://WhiteDwarf.org/donate/.

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The Internal Structure of White Dwarf Stars Using the Whole Earth Telescope

International Astronomical Union Colloquium ◽

10.1017/s0252921100117051 ◽

1993 ◽

Vol 139 ◽

pp. 117-119

Author(s):

P.A. Bradley

Keyword(s):

Internal Structure ◽

Stellar Evolution ◽

White Dwarf ◽

White Dwarfs ◽

Dwarf Stars ◽

White Dwarf Stars ◽

History Of ◽

The Way ◽

Whole Earth

AbstractWhite dwarfs are the final end state for the majority of stars, and hold clues to help solve many current pressing astrophysical problems. We can perform asteroseismology on the pulsating white dwarfs to better understand their internal structure and input physics, paving the way to a better understanding of astrophysics, stellar evolution, and the history of our Galaxy. I describe briefly the potential of asteroseismology by using it to infer the internal structure of PG1159-035.

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Probing the Extraordinary Ends of Ordinary Stars: White Dwarf Seismology with the Whole Earth Telescope

International Astronomical Union Colloquium ◽

10.1017/s0252921100036800 ◽

1995 ◽

Vol 155 ◽

pp. 81-91

Author(s):

Steven D. Kawaler

Keyword(s):

White Dwarf ◽

High Speed ◽

Dwarf Stars ◽

White Dwarf Stars ◽

Dense Cores ◽

Photometric Observations ◽

Nuclear Burning ◽

Stellar Seismology ◽

Composition Changes ◽

Whole Earth

AbstractDuring the final evolution of most stars, they shed their outer skin and expose their core of the hot ashes of nuclear burning. As these hot and very dense cores cool into white dwarf stars, they go through episodes of multiperiodic, nonradial g-mode pulsation. The tools of stellar seismology allow us to use the pulsation spectra as powerful probes into the deep interiors of these stars. Progress in white dwarf seismology has required significant international cooperation, since another consequence of the complex pulsations of these stars is decoding the true pulsation frequencies requires a coordinated global effort involving high-speed photometric observations. Through one such effort, the Whole Earth Telescope project, we have located subsurface composition changes, detected differential rotation and magnetic fields, and measured fundamental quantities such as stellar mass, luminosity, and distance to extraordinary accuracy.

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The Time Dependence of the Phases of the Harmonics Relative to the 1490 sec Fundamental in PG1346+082

International Astronomical Union Colloquium ◽

10.1017/s0252921100099759 ◽

1989 ◽

Vol 114 ◽

pp. 296-299

Author(s):

J. L. Provencal ◽

J. C. Clemens ◽

G. Henry ◽

B. P. Hine ◽

R. E. Nather ◽

...

Keyword(s):

White Dwarf ◽

Compact Object ◽

Detailed Knowledge ◽

Line Profiles ◽

Pressure Broadening ◽

Dwarf Stars ◽

White Dwarf Stars ◽

Adequate Understanding ◽

Magnitude Variation ◽

Hydrogen Lines

White dwarf stars provide important boundary conditions for the understanding of stellar evolution. An adequate understanding of even these simple stars is impossible without detailed knowledge of their interiors. PG1346+082, an interacting binary white dwarf system, provides a unique opportunity to view the interior of one degenerate as it is brought to light in the accretion disk of the second star as the primary strips material from its less massive companion (see Wood et at. 1987).PG1346+082 is a photometric variable with a four magnitude variation over a four to five day quasi-period. A fast Fourier transform (FFT) of the light curve shows a complex, time-dependent structure of harmonics. PG1346+082 exhibits flickering – the signature of mass transfer. The optical spectra of the system contain weak emission features during minimum and broad absorption at all other times. This could be attributed to pressure broadening in the atmosphere of a compact object, or to a combination of pressure broadening and doppler broadening in a disk surrounding the compact accretor. No hydrogen lines are observed and the spectra are dominated by neutral helium. The spectra also display variable asymmetric line profiles.

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