Oliveira, JM, Jeffries, RD, Loon, JTV and Kenyon, MJ (2003) Young stars and their circumstellar disks in the Sigma Orionis cluster. In: Open Issues in Local Star Formation and Early Stellar Evolution, 5-10 Apr 2003, Ouro Preto, Minas Gerais, Brazil.

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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.

Item Type: Conference or Workshop Item (Paper)
Uncontrolled Keywords: astrophysics, stars
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Related URLs:
Depositing User: Symplectic
Date Deposited: 19 May 2015 09:27
Last Modified: 10 Jul 2019 14:23
URI: https://eprints.keele.ac.uk/id/eprint/527

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