Journal Article

The incidence of mid-infrared excesses in G and K giants

Mark H. Jones

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 387, issue 2, pages 845-855
Published in print June 2008 | ISSN: 0035-8711
Published online May 2008 | e-ISSN: 1365-2966 | DOI:
The incidence of mid-infrared excesses in G and K giants

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Using photometric data from the Two-Micron All-Sky Survey (2MASS) and GLIMPSE catalogues, I investigate the incidence of mid-infrared (mid-IR) excesses (∼10 μm) in G and K stars of luminosity class III. In order to obtain a large sample size, stars are selected using a near-IR colour–magnitude diagram. Sources which are candidates for showing mid-IR excess are carefully examined and modelled to determined whether they are likely to be G/K giants. It is found that mid-IR excesses are present at a level of (1.8 ± 0.4) × 10−3. While the origin of these excesses remains uncertain, it is plausible that they arise from debris discs around these stars. I note that the measured incidence is consistent with a scenario in which dust lifetimes in debris discs are determined by Poynting–Robertson drag rather than by collisions.

Keywords: circumstellar matter; infrared: stars

Journal Article.  8092 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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