Cool Customers in the Stellar Graveyard I Limits to Extrasolar Planets Around the White Dwa.pdfVIP

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2017-04-11 发布于江苏
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Cool Customers in the Stellar Graveyard I Limits to Extrasolar Planets Around the White Dwa.pdf

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Cool Customers in the Stellar Graveyard I Limits to Extrasolar Planets Around the White Dwa

a r X i v : a s t r o - p h / 0 4 1 2 6 6 8 v 2 2 8 S e p 2 0 0 5 Cool Customers in the Stellar Graveyard I: Limits to Extrasolar Planets around the White Dwarf G29-38 John H. Debes1, Steinn Sigurdsson1, Bruce E. Woodgate2 ABSTRACT We present high contrast images of the hydrogen white dwarf G 29-38 taken in the near infrared with the Hubble Space Telescope and the Gemini North Telescope as part of a high contrast imaging search for substellar objects in orbit around nearby white dwarfs. We review the current limits on planetary companions for G29-38, the only nearby white dwarf with an infrared excess due to a dust disk. We add our recent observations to these limits to produce extremely tight constraints on the types of possible companions that could be present. No objects 6 MJup are detected in our data at projected separations 12 AU, and no objects 16 MJup are detected for separations from 3 to 12 AU, assuming a total system age of 1 Gyr. Limits for companions at separations 3 AU come from a combination of 2MASS photometry and previous studies of G29-38’s pulsations. Our imaging with Gemini cannot confirm a tentative claim for the presence of a low mass brown dwarf. These observations demonstrate that a careful combination of several techniques can probe nearby white dwarfs for large planets and low mass brown dwarfs. Subject headings: circumstellar matter — planetary systems — white dwarfs — stars: individual (G29-38) 1. Introduction G29-38 (ZZ Psc, WD 2326+049, GJ 895.2) is a nearby (d=13.6 pc) non-radially pulsat- ing hydrogen white dwarf (WD) with photospheric absorption lines due to metals such as Mg and Ca (van Altena et al. 2001; Koester et al. 1997). Hydrogen WDs with metal absorption lines are known as DAZs. G29-38 has a measured gravity log g= 8.15 and a Teff=11820 K, placing its cooling age at 0.6 Gyr (Liebert et al. 2005). 1Department of Astronomy Astrophysics, Pennsylvania State University, University Park, PA 16802 2NASA Goddard Space Flig