Revealing the Chamaeleon: First detection of a low-mass stellar halo around the young open cluster Eta Chamaeleontis

We have identified several lithium-rich low-mass (0.08 < M < 0.3 M_☉). stars within 5.5 deg of the young open cluster η Chamaeleontis, nearly four times the radius of previous search efforts. We propose 4 new probable cluster members and 3 possible members requiring further investigation. Candidates were selected on the basis of DENIS and 2MASS photometry, NOMAD astrometry and extensive follow-up spectroscopy. Several of these stars show substantial variation in their Hα emission line strengths on timescales of days to months, with at least one event attributable to accretion from a circumstellar disk. These findings are consistent with a dynamical origin for the current configuration of the cluster, without the need to invoke an abnormally top-heavy Initial Mass Function, as proposed by some authors.

star: cluster
star: mass
matter: accretion
NOMAD
halo
lithium
chameleon
experimental results

References(1)

Figures(8)

Evolutionary models for solar metallicity low - mass stars: Mass - magnitude relationships and color - magnitude diagrams

- Astron.Astrophys. 337 (1998) 403-412
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e-Print:
- astro-ph/9805009