Saturday, December 3, 2016

Faint Warm Debris Disks Around Nearby Bright Stars


Authors:

Ishihara et al

Abstract:

Context:

Debris disks are important observational clues for understanding planetary-system formation process. In particular, faint warm debris disks may be related to late planet formation near 1 AU. A systematic search of faint warm debris disks is necessary to reveal terrestrial planet formation.

Aims:

Faint warm debris disks show excess emission that peaks at mid-IR wavelengths. Thus we explore debris disks using the AKARI mid-IR all-sky point source catalog (PSC), a product of the second generation unbiased IR all-sky survey.

Methods:

We investigate IR excess emission for 678 isolated main-sequence stars for which there are 18 micron detections in the AKARI mid-IR all-sky catalog by comparing their fluxes with the predicted fluxes of the photospheres based on optical to near-IR fluxes and model spectra. The near-IR fluxes are first taken from the 2MASS PSC. However, 286 stars with Ks<4 .5="" 1.4="" 1.8="" 14="" 2mass="" accuracy="" accurate="" africa="" and="" applying="" average.="" band="" br="" density="" due="" errors="" filters="" flux="" fluxes="" for="" from="" h="" have="" imager="" improved="" in="" infrared="" irsf="" j="" ks="" large="" m="" measured="" near-ir="" neutral="" on="" our="" phi="" photometry="" sample="" saturation.="" simultaneous="" south="" survey="" telescope="" the="" thus="" to="" unbiased="" we="">
Results:

We identified 53 debris-disk candidates including eight new detections from our sample of 678 main-sequence stars. The detection rate of debris disks for this work is ~8%, which is comparable with those in previous works by Spitzer and Herschel.

Conclusion:

The importance of this study is the detection of faint warm debris disks around nearby field stars. At least nine objects have a large amount of dust for their ages, which cannot be explained by the conventional steady-state collisional cascade model.

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