Bibcode
Wang, W.; Boudreault, S.; Goldman, B.; Henning, Th.; Caballero, J. A.; Bailer-Jones, C. A. L.
Referencia bibliográfica
16th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun. ASP Conference Series, Vol. 448, proceedings of a conference held August 28- September 2, 2010 at the University of Washington, Seattle, Washington. Edited by Christopher M. Johns-Krull, Matthew K. Browning, and Andrew A. West. San Francisco: Astronomical Society of the Pacific, 2012., p.761
Fecha de publicación:
12
2011
Número de citas
1
Número de citas referidas
1
Descripción
Studies of the mass function (MF) of open clusters of different ages
allow us to probe the efficiency with which brown dwarfs (BDs) are
evaporated from clusters to populate the field. Surveys in old clusters
(age gtrsim 100 Myr) do not suffer so severely from several problems
encountered in young clusters, such as intra-cluster extinction and
large uncertainties in BD models. Here we present the results of a deep
photometric survey to study the MF of the old open cluster Praesepe (age
590+150-120 Myr and distance
190+6.0-5.8 pc), down to a 5σ detection
limit at i˜25.6 mag (˜40 MJup). We identify 62
cluster member candidates, of which 40 are substellar, from comparison
with predictions from a dusty atmosphere model. The MF rises from the
substellar boundary until ˜60 MJup and then declines.
This is quite different from the form inferred for other open clusters
older than 50 Myr, but seems to be similar to those found in very young
open cluster, whose MFs peak at ˜10 MJup. Either
Praesepe really does have a different MF from other clusters or they had
similar initial MFs but have differed in their dynamical evolution. We
further have identified six foreground T dwarf candidates towards
Praesepe, which require follow-up spectroscopy to confirm their nature.