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Rotational and Candidate-Eclipsing-Binary Light Curves for Pre-Main-Sequence Stars in the Chamaeleon I Star-Forming Cloud

Published online by Cambridge University Press:  05 March 2013

Warrick A. Lawson  and
Lisa A. Crause
Warrick A. Lawson*
Affiliation:
School of Physical, Enviromental & Mathematical Sciences, University of New South Wales, Australian Defence Force Academy, Canberra, ACT 2600, Australia
Lisa A. Crause
Affiliation:
South African Astronomical Observatory, P.O. Box 9, Observatory 7935, South Africa
*
CCorresponding author. Email: w.lawson@adfa.edu.au
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Abstract

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We present the results of a photometric survey for variability in ten X-ray-emitting low-mass stars in the Chamaeleon region. Eight of the stars we observed are bona fide pre-main-sequence members of the ∼2 Myr-old Chamaeleon I star-forming cloud. The other two stars are young with high levels of relative X-ray emission, but with discordant proper motions they are probable non-members of the cloud. In six of the stars we monitored, periodic variations on timescales of 2.5–11.5 d were detected, that we ascribe to stellar rotation and the presence of cool starspots. Two other stars, CHXR 20 and CHXR 85, show large amplitude variations at visual and near-infrared wavelengths and are candidate eclipsing binaries. Compared to the rotational properties of low-mass stars in the ≈8 Myr-old η Chamaeleontis cluster, we find that the older η Chamaeleontis stars have several times higher surface specific angular momentum than the younger Chamaeleon I stars. The apparent increase in angular momentum between ∼2 and 8 Myr might be due to changes in stellar internal structure as the stars evolve, or evidence for a different rotational history between members of the two star-forming regions.

Keywords

open clusters and associations: individual (Chamaeleon I)stars: individual (CHXR 3, CHXR 20, CHXR 33, CHXR 37, CHXR 40, CHXR 47, CHXR 53, CHXR 59, CHXR 71, CHXR 85)stars: pre-main sequencestars: rotationstars: spotsbinaries: eclipsing
Type
Research Article
Information
Publications of the Astronomical Society of Australia , Volume 26 , Issue 1 , 2009 , pp. 31 - 36
Copyright
Copyright © Astronomical Society of Australia 2009

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