K-band Luminosity Function of a Distant Embedded Cluster

Carlos A. Santos
Centro de Astronomia e Astrofísica da Universidade de Lisboa
Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal

João L. Yun
Centro de Astronomia e Astrofísica da Universidade de Lisboa
Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal

We report VLT observations of the most distant embedded young stellar cluster located far in the outer Galaxy. The cluster is resolved in near-infrared images centered close to IRAS 07255–2012.
The cluster is embedded in a molecular cloud containing a CS dense core. The molecular cloud, as traced by CO (J=1-0) is elongated and extends over a region of 15 × 6 pc2 . From the millimeter observations, we derive a kinematic distance of 10.2 kpc and a Galactocentric distance of 16.5 kpc.
The cluster is well confined to a region of about 1.2 pc in radius. Down to our detection limit of about 0.5 Mo at this distance, it contains at least 190 members. A reasonable fraction of these (45%) exhibit near-infrared color excesses consistent with young stellar objects having circumstellar and/or envelope material.
The K-band luminosity function of the cluster is well fitted by a power-law with a slope of 0.35 ( ± 0.05), down to MKs ~3.6.

Grupo de Astronomia da Universidade da Madeira - 2001