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| Paper: |
The Substellar Mass Function in the Central Region of the Open
Cluster Praesepe from Deep LBT Observations |
| Volume: |
448, 16th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun |
| Page: |
761 |
| Authors: |
Wang, W.; Boudreault, S.; Goldman, B.; Henning, Th.; Caballero, J. A.; Bailer-Jones, C. A. L. |
| Abstract: |
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 M{rm
Jup}). 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. |
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