Paper: astro-ph/0511358
Date: Fri, 11 Nov 2005 16:32:59 GMT (59kb)

Title: The Dust cloud around the White Dwarf G 29-38

Authors: William T. Reach, Marc J. Kuchner, Ted von Hippel, Adam Burrows,
Fergal Mullally, Mukremin Kilic, D. E. Winget

Comments: accepted for publication in the Astrophysical Journal Letters
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We present new observations of the white dwarf G 29-38 with the camera (4.5
and 8 microns), photometer (24 microns), and spectrograph (5.5-14 microns) of
the Spitzer Space Telescope. This star has an exceptionally large infrared
excess amounting to 3% of the bolometric luminosity. The spectral energy
distribution has a continuum peak around 4.5 micros and a 9-11 micron emission
feature 1.25 times brighter than the continuum. A mixture of amorphous olivine
and a small amount of forsterite in an emitting region 1-5 Rsun from the star
can reproduce the shape of the 9-11 micron feature. The spectral energy
distribution also appears to require amorphous carbon to explain the hot
continuum. Our new measurements support the idea that a relatively recent
disruption of a comet or asteroid created the cloud.

\\ ( http://arXiv.org/abs/astro-ph/0511358 , 59kb)