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No disks around low-mass stars and brown dwarfs in the young sigma Orionis cluster?

Oliveira, JM; Jeffries, RD; Kenyon, MJ; Thompson, SA; Naylor, Tim

No disks around low-mass stars and brown dwarfs in the young sigma Orionis cluster? Thumbnail


Authors

MJ Kenyon

SA Thompson

Tim Naylor



Abstract

We report on the analysis of 2MASS near-infrared data of a sample of low-mass stars and brown dwarfs in the sigma Orionis cluster. Youth and cluster membership have been spectroscopically confirmed using the Li I spectral line. We find little evidence in the JHKs colour-colour diagram for near-infrared excess emission for these cluster members. By comparison with model expectations, at most 2 out of 34 stars show (H-K) colour consistent with a near-infrared excess. This scarcity of near-infrared signatures of circumstellar disks in the lower-mass and substellar regimes of this cluster contrasts with findings in younger clusters, hinting at an age dependence of the disk frequency. Taking into account the apparent cluster age, our result supports the idea of a relatively fast (few Myr) disk dissipation and extends this conclusion to the substellar regime. We also find some evidence that, in this cluster, the disk frequency as measured by the Ks-band excess may be mass dependent.

Journal Article Type Letter
Acceptance Date Dec 13, 2001
Online Publication Date Feb 15, 2002
Publication Date Feb 1, 2002
Publicly Available Date Mar 28, 2024
Journal Astronomy & Astrophysics
Print ISSN 0004-6361
Publisher EDP Sciences
DOI https://doi.org/10.1051/0004-6361%3A20011778
Keywords circumstellar matter infrared, stars, pre-main sequence, low mass, brown dwarfs, open clusters and associations, individual (s Orionis)
Publisher URL http://dx.doi.org/10.1051/0004-6361:20011778

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