Young stars and their circumstellar disks in the Sigma Orionis cluster

The sigma Orionis cluster is a young association evolving under the disruptive influence of its massive O-star namesake. We are analysing this cluster as part of a program to characterise the influence of O-stars on the early stages of stellar evolution. At an age of approximately 4 Myr, this cluste...

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Bibliographic Details
Published in:arXiv.org 2003-05
Main Authors: Oliveira, J M, Jeffries, R D, van Loon, J Th, Kenyon, M J
Format: Article
Language:English
Subjects:
Accretion disks
Brown dwarf stars
Infrared imaging
Photometry
Sigma Orionis
Spectrum analysis
Star & galaxy formation
Star clusters
Stellar age
Stellar evolution
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Summary:The sigma Orionis cluster is a young association evolving under the disruptive influence of its massive O-star namesake. We are analysing this cluster as part of a program to characterise the influence of O-stars on the early stages of stellar evolution. At an age of approximately 4 Myr, this cluster is at a crucial stage in terms of disk evolution and therefore it is a key case to better constrain disk dissipation timescales. We have obtained RI photometry and optical spectroscopy of the sigma Ori cluster; we have analysed the Li I and Na I features to establish cluster membership. We have thus gathered a unique sample of spectroscopically confirmed low-mass cluster members and brown dwarfs. Disk frequencies from K-band excesses from 2MASS suggest that less than 7% of the very low-mass sigma Ori members have disks, in stark contrast with even younger clusters (e.g. Trapezium). However, near-infrared disk frequencies have to be taken with caution. We are currently undertaking an L-band (imaging) and mid-infrared (imaging and spectroscopy) program to identify and probe the properties of circumstellar disks around young stars in this cluster. Preliminary results indicate that at least 30% of cluster members have circumstellar disks.
ISSN:2331-8422
DOI:10.48550/arxiv.0305501