2001AJ....121.2053A -
Astron. J., 121, 2053-2064 (2001/April-0)
The mass and structure of the Pleiades star cluster from 2MASS.
ADAMS J.D., STAUFFER J.R., MONET D.G., SKRUTSKIE M.F. and BEICHMAN C.A.
Abstract (from CDS):
We present the results of a large-scale search for new members of the Pleiades star cluster using 2MASS near-infrared photometry and proper motions derived from POSS plates digitized by the USNO PMM program. The search extends to a 10° radius around the cluster, well beyond the presumed tidal radius, to a limiting magnitude of R∼20, corresponding to ∼0.07 M☉ at the distance and age of the Pleiades. Multiobject spectroscopy for 528 candidates verifies that the search was extremely effective at detecting cluster stars in the 1-0.1 M☉ mass range using the distribution of Hα emission strengths as an estimate of sample contamination by field stars. When combined with previously identified, higher mass stars, this search provides a sensitive measurement of the stellar mass function and dynamical structure of the Pleiades. The degree of tidal elongation of the halo agrees well with current N-body simulation results. Tidal truncation affects masses below ∼1 M☉. The cluster contains a total mass ∼800 M☉. Evidence for a flatter mass function in the core than in the halo indicates the depletion of stars in the core with mass less than ∼0.5 M☉, relative to stars with mass ∼1-0.5 M☉, and implies a preference for very low-mass objects to populate the halo or escape. The overall mass function is best fitted with a lognormal form that becomes flat at ∼0.1 M☉. Whether sufficient dynamical evaporation has occurred to detectably flatten the initial mass function, via preferential escape of very low-mass stars and brown dwarfs, is undetermined, pending better membership information for stars at large radial distances.
Abstract Copyright:
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Journal keyword(s):
Astrometry - celestial mechanics - Galaxy: Open Clusters and Associations: Individual: Name: Pleiades - Stars: Low-Mass, Brown Dwarfs
Simbad objects:
10
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