Bibcode
de Wit, W. J.; Bouvier, J.; Palla, F.; Cuillandre, J.-C.; James, D. J.; Kendall, T. R.; Lodieu, N.; McCaughrean, M. J.; Moraux, E.; Randich, S.; Testi, L.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 448, Issue 1, March II 2006, pp.189-202
Fecha de publicación:
3
2006
Revista
Número de citas
32
Número de citas referidas
23
Descripción
We present a study of the young (30-100 Myr) open cluster IC 4665 with
the aim to determine the shape of the mass function well into the brown
dwarf regime. We photometrically select 691 low-mass stellar and 94
brown dwarf candidate members over an area of 3.82 square degrees
centred on the cluster. K-band follow-up photometry and Two-Micron
All-Sky Survey data allow a first filtering of contaminant objects from
our catalogues. A second filtering is performed for the brightest stars
using proper motion data provided by the Tycho-2 and UCAC2 public
catalogues. Contamination by the field population for the lowest mass
objects is estimated using same latitude control fields. We fit observed
surface densities of various cluster populations with King profiles and
find a consistent tidal radius of 1.0°. The presence of possible
mass segregation is discussed. In most respects investigated, IC 4665 is
similar to other young open clusters at this age: (1) a power law fit to
the mass function between 1 and 0.04 M&sun; results in best
fit for a slope of -0.6; (2) a cusp in the mass function is noticed at
about the substellar boundary with respect to the power law description,
the interpretation of which is discussed; (3) a fraction between 10-19%
for BDs with M ⪆ 0.03 M&sun; to total members; (4) a
best-fit lognormal function to the full mass distribution shows an
average member mass of 0.32 M&sun;, if IC 4665 has an age of
50 Myr.