Volume 515, June 2010
|Number of page(s)||14|
|Section||Galactic structure, stellar clusters, and populations|
|Published online||03 June 2010|
European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago 19, Chile e-mail: firstname.lastname@example.org
2 Sterrenkundig Instituut Anton Pannekoek, Universiteit van Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
3 INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy
4 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
Accepted: 1 March 2010
We present adaptive optics (AO) near-infrared observations of the core of the Tr 14 cluster in the Carina region obtained with the ESO multi-conjugate AO demonstrator, MAD. Our campaign yields AO-corrected observations with an image quality of about 0.2´´ across the 2´ field of view, which is the widest AO mosaic ever obtained. We detected almost 2000 sources spanning a dynamic range of 10 mag. The pre-main sequence (PMS) locus in the colour-magnitude diagram is well reproduced by Palla & Stahler isochrones with an age of 3 to 5×105 yr, confirming the very young age of the cluster. We derive a very high (deprojected) central density n0 ~ 4.5(±0.5)×104 pc-3 and estimate the total mass of the cluster to be about ~×103 , although contamination of the field of view might have a significant impact on the derived mass. We show that the pairing process is largely dominated by chance alignment so that physical pairs are difficult to disentangle from spurious ones based on our single epoch observation. Yet, we identify 150 likely bound pairs, 30% of these with a separation smaller than 0.5´´ (~1300 AU). We further show that at the 2σ level massive stars have more companions than lower-mass stars and that those companions are respectively brighter on average, thus more massive. Finally, we find some hints of mass segregation for stars heavier than about 10 . If confirmed, the observed degree of mass segregation could be explained by dynamical evolution, despite the young age of the cluster.
Key words: instrumentation: adaptive optics / stars: early-type / stars: pre-main sequence / binaries: visual / open clusters and associations: individual: Tr 14
Based on observations obtained with the MCAO Demonstrator (MAD) at the VLT Melipal Nasmyth focus (ESO public data release).
Full Tables [see full textsee full text] and [see full textsee full text] are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (22.214.171.124) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/515/A26
© ESO, 2010
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