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Session 15 - Planetary Nebulae and White Dwarfs.
Display session, Wednesday, January 07
Exhibit Hall,
We present the Hipparcos parallaxes and resulting radii for 10 white dwarfs in visual binaries or common proper motion systems, and 11 field white dwarfs. For bright stars, Hipparcos parallaxes have uncertainties approaching 1 milliarcsecond and are thus considerably more accurate than earlier ground based parallaxes. Overall, our results support the predictions of the white dwarf mass-radius relation and our understanding of stellar degeneracy. Our most important finding for an individual object is the position of 40 Eri B, a well known puzzle now consistent with single star evolution. In addition, we present evidence supporting the existence of a range of atmosphere thicknesses for hydrogen white dwarfs, as well as tantalizing suggestions of white dwarfs with cores heavier than carbon.
