SPITZER 24 {mu}m SURVEY FOR DUST DISKS AROUND HOT WHITE DWARFS

Journal Article · Thu Sep 15 04:00:00 EDT 2011 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/142/3/75· OSTI ID:21582949

Chu, You-Hua; Bilikova, Jana; Gruendl, Robert A ^[1]; Su, Kate Y. L. ^[2]; De Marco, Orsola ^[3]; Guerrero, Martin A ^[4]; Updike, Adria C ^[5]; Volk, Kevin ^[6]; Rauch, Thomas ^[7]

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1. Department of Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)
2. Stewart Observatory, University of Arizona, Tucson, AZ 85721 (United States)
3. Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109 (Australia)
4. Instituto de Astrofisica de Andalucia, CSIC, E-18008 Granada (Spain)
5. CRESST and the Observational Cosmology Laboratory, NASA/GSFC, Greenbelt, MD 20771 (United States)
6. Space Telescope Science Institute, Baltimore, MD 21218 (United States)
7. Institut fuer Astronomie und Astrophysik Tuebingen (IAAT), Abteilung Astronomie, D-72076 Tuebingen (Germany)

Two types of dust disks around white dwarfs (WDs) have been reported: small dust disks around cool metal-rich WDs consisting of tidally disrupted asteroids and a large dust disk around the hot central WD of the Helix planetary nebula (PN) possibly produced by collisions among Kuiper-Belt-like objects. To search for more dust disks of the latter type, we have conducted a Spitzer MIPS 24 {mu}m survey of 71 hot WDs or pre-WDs, among which 35 are central stars of PNe (CSPNs). Nine of these evolved stars are detected and their 24 {mu}m flux densities are at least two orders of magnitude higher than their expected photospheric emission. Considering the bias against the detection of distant objects, the 24 {mu}m detection rate for the sample is {approx}>15%. It is striking that seven, or {approx}20%, of the WD and pre-WDs in known PNe exhibit 24 {mu}m excesses, while two, or 5%-6%, of the WDs not in PNe show 24 {mu}m excesses and they have the lowest 24 {mu}m flux densities. We have obtained follow-up Spitzer Infrared Spectrograph spectra for five objects. Four show clear continuum emission at 24 {mu}m, and one is overwhelmed by a bright neighboring star but still shows a hint of continuum emission. In the cases of WD 0950+139 and CSPN K 1-22, a late-type companion is present, making it difficult to determine whether the excess 24 {mu}m emission is associated with the WD or its red companion. High-resolution images in the mid-infrared are needed to establish unambiguously the stars responsible for the 24 {mu}m excesses.

• OSTI ID: 21582949
• Journal Information: Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 3 Vol. 142; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTEROIDS
DUSTS
DWARF STARS
EMISSION
FLUX DENSITY
NEBULAE
PLANETARY NEBULAE
STARS
WHITE DWARF STARS