Extent of excess far-infrared emission around luminosity class III stars

Citation
Ss. Kim et al., Extent of excess far-infrared emission around luminosity class III stars, ASTROPHYS J, 550(2), 2001, pp. 1000-1006
Citations number
14
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
ASTROPHYSICAL JOURNAL
ISSN journal
0004-637X → ACNP
Volume
550
Issue
2
Year of publication
2001
Part
1
Pages
1000 - 1006
Database
ISI
SICI code
0004-637X(20010401)550:2<1000:EOEFEA>2.0.ZU;2-W
Abstract
With the Infrared Space Observatory, we conducted 3 x 3 pixel imaging photo metry of 12 luminosity class III stars, which were previously presumed to h ave dust particles around them, at far-infrared wavelengths (60 and 90 mum) . Eleven out of 12 targets show a peak of excess (above photosphere) far-in frared emission at the location of the star, implying that the dust particl es are truly associated with stars. To estimate the size of the excess emis sion source, the flux ratio of center to boundary pixels of the 3 x 3 array was examined. The radius of the dust emission is found to be similar to 30 00 to similar to 10,000 AU for a thin shell distribution and similar to 500 0 to similar to 25,000 AU for a uniform distribution. We consider three mod els for the origin of the dust: disintegration of comets, sporadic dust eje ction from the star, and emission from nearby interstellar cirrus. The data seem to rule out the first model (as far as the "Kuiper belt-like" particl es are assumed to be large blackbody grains) but do not enable us to choose between the other two models.