Spitzer space telescope observations of magnetic cataclysmic variables:: Possibilities for the presence of dust in polars

被引:29
作者
Brinkworth, C. S. [1 ]
Hoard, D. W.
Wachter, S.
Howell, S. B.
Ciardi, David R.
Szkody, P.
Harrison, T. E.
van Belle, G. T.
Esin, A. A.
机构
[1] CALTECH, Spitzer Sci Ctr, Pasadena, CA 91125 USA
[2] Natl Opt Astron Observ, WIYN Observ, Tucson, AZ 85719 USA
[3] CALTECH, Michelson Sci Ctr, Pasadena, CA 91125 USA
[4] Univ Washington, Dept Astron, Seattle, WA 98195 USA
[5] New Mexico State Univ, Dept Astron, Las Cruces, NM 88003 USA
关键词
infrared : stars; stars; low-mass; brown dwarfs; stars : magnetic fields;
D O I
10.1086/512797
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present Spitzer photometry of six short-period polars, EF Eri, V347 Pav, VV Pup, V834 Cen, GG Leo, and MR Ser. We have combined the Spitzer IRAC (3.6-8.0 mu m) data with the 2MASS JHK(s) photometry to construct the SEDs of these systems from the near- to mid-IR (1.235-8 mu m). We find that five out of the six polars have flux densities in the mid-IR that are substantially in excess of the values expected from the stellar components alone. We have modeled the observed SEDs with a combination of contributions from the white dwarf, secondary star, and either cyclotron emission or a cool, circumbinary dust disk to fill in the long-wavelength excess. We find that a circumbinary dust disk is the most likely cause of the 8 mu m excess in all cases, but we have been unable to rule out the specific ( but unlikely) case of completely optically thin cyclotron emission as the source of the observed 8 mu m flux density. While both model components can generate enough flux at 8 mu m, neither dust nor cyclotron emission alone can match the excess above the stellar components at all wavelengths. A model combining both cyclotron and dust contributions, possibly with some accretion-generated flux in the near-IR, is probably required, but our observed SEDs are not sufficiently well sampled to constrain such a complicated model. If the 8 mu m flux density is caused by the presence of a circumbinary dust disk, then our estimates of the masses of these disks are many orders of magnitude below the mass required to affect CV evolution.
引用
收藏
页码:1541 / 1562
页数:22
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