A MAD view of Trumpler 14

Abstract

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 × 10 5 yr, confirming the very young age of the cluster. We derive a very high (deprojected) central density n 0 ∼ 4.5(±0.5) × 10 4 pc −3 and estimate the total mass of the cluster to be about ∼4.3 +3.3 −1.5 × 10 3 M , 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 M . If confirmed, the observed degree of mass segregation could be explained by dynamical evolution, despite the young age of the cluster.

A dearth of short-period massive binaries in the young massive star forming region M 17

“…The present results from the M 17 region seem to be corroborated by the multiplicity properties of Tr14, a dense young cluster (<1 Myr, Sana et al 2010) in the Carina nebula. Though it has only six O stars with RV information (Sana & Evans 2011), none of them has been detected as a short-period binary (though see Maíz Apellániz et al 2017, for HD 93129A).…”

The VISTA Carina Nebula Survey

“…This effect is, however, mainly restricted to the extremely dense cluster Tr 14 near the center of the Carina Nebula, where the very strong source crowding leads to considerable incompleteness of the VISTA catalog. Observations with much better angular resolution are required for detailed studies of such dense clusters; for Tr 14, we note that results of adaptive-optics observations have been presented by Ascenso et al (2007) and Sana et al (2010).…”

The multiplicity of massive stars

“…These two studies are mostly limited to the northern hemisphere and are thus missing some of the richer massive star clusters and associations in the southern sky. Part of this gap is filled by the AO campaigns of Duchêne et al (2001) and Sana et al (2010b) on, respectively, NGC 6611 and Tr 14. Both studies revealed a lower multiplicity fraction of 18% for their sample of OB stars.…”

“…In these environments, disentangling the true pairs from chance alignment with stars in the same clusters becomes more challenging and only a smaller separation range can be investigated reliably. Interestingly, both Duchêne et al (2001) and Sana et al (2010b) concluded that OB stars have more companions than lower mass-stars.…”