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Dwarf Novae

7 Apr 2012, 19:26 UTC
Dwarf Novae
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We have a guest post from Martin Still. Martin is Deputy Science Team Lead and Guest Observer Office Director for Kepler. He’s writing today to tell you about an interesting class of objects you might encounter when classifying Kepler light curves
Dwarf novae are binary stars consisting of a white dwarf and main sequence companion. The binary orbit of period a few hours is small enough that the outer atmosphere of the main sequence star is being stripped through gravitational influence by the white dwarf, and gas is falling in a steady stream towards the surface of the white dwarf. The light from the binary stars is dominated not by the stellar components but the accreting material configured around the white dwarf within an accretion disk. The brightness of the accretion disk is coupled strongly to the temperature and density of the disk. Brightness changes over the timescales of a few days and several magnitudes indicate changes in the density and temperature of the disk. Coherent oscillations in the light curves of dwarf novae on timescales of a few hours indicate the orbital period of the binary and tidally-driven distortions in the accretion disk. To identify dwarf novae, look for ...

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