Spitzer IRAC Observations of White Dwarfs. I. Warm Dust at Metal-Rich Degenerates
Abstract
This paper presents the results of a Spitzer IRAC 3-8 μm photometric search for warm dust orbiting 17 nearby, metal-rich white dwarfs, 15 of which apparently have hydrogen-dominated atmospheres (type DAZ). G166-58, G29-38, and GD 362 manifest excess emission in their IRAC fluxes and the latter two are known to harbor dust grains warm enough to radiate detectable emission at near-infrared wavelengths as short as 2 μm. Their IRAC fluxes display differences compatible with a relatively larger amount of cooler dust at GD 362. G166-58 is presently unique in that it appears to exhibit excess flux only at wavelengths longer than about 5 μm. Evidence is presented that this mid-infrared emission is most likely associated with the white dwarf, indicating that G166-58 bears circumstellar dust no warmer than T ~ 400 K. The remaining 14 targets reveal no reliable mid-infrared excess, indicating the majority of DAZ stars do not have warm debris disks sufficiently opaque to be detected by IRAC.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2008
- DOI:
- 10.1086/521715
- arXiv:
- arXiv:0710.0907
- Bibcode:
- 2008ApJ...674..431F
- Keywords:
-
- circumstellar matter;
- infrared: stars;
- minor planets;
- asteroids;
- planetary systems;
- stars: abundances;
- stars: evolution;
- stars: individual: G166-58 G29-38 GD 362 PG 0235+064;
- white dwarfs;
- Astrophysics
- E-Print:
- Accepted to ApJ, 10 figures, 6 tables