The Debris Disk Candidates: Eleven 24$\mu$m excess stars in Spitzer SWIRE Fields

TL;DR

This study identifies 11 late-type main-sequence stars with mid-infrared excesses from Spitzer SWIRE data, indicating the presence of debris disks, including some with high fractional luminosities in old stellar populations.

Contribution

First identification of high fractional luminosity debris disk candidates in old, high-galactic latitude stars using multi-wavelength data.

Findings

11 debris disk candidates identified with 24μm excess.

Candidates are late-type main-sequence stars with high fractional luminosities.

Debris disks may persist in old stellar systems at high galactic latitudes.

Abstract

We present the optical to mid-infrared SEDs of 11 debris disk candidates from $Spitzer$ SWIRE fields. All these candidates are selected from SWIRE 24$\mu$m sources matched with both the SDSS star catalog and the 2MASS point source catalog. They show an excess in the mid-infrared at 24$\mu$m ($K_S$-[24]$_{Vega}$ $\ge$ 0.44) indicating the presence of a circumstellar dust disk. The observed optical spectra show that they are all late type main-sequence stars covering the spectral types of FGKM. Their fractional luminosities are well above 5$\times10^{-5}$, even up to the high fractional luminosity of 1$\times10^{-3}$. The high galactic latitudes of SWIRE fields indicate that most of these candidates could belong to the oldest stars in the thick disk. Our results indicate that the high fractional luminosity debris disks could exist in the old solar-like star systems, though they are now still quite rare. Their discoveries at high-galactic latitudes will also provide us an excellent opportunity to the further studies of properties and evolution of the debris disk in the ISM poor environments.