Deep wide-field near-infrared survey of the Carina Nebula

Abstract

Context. The Great Nebula in Carina is a giant H ii region and a superb location in which to study the physics of violent massive star formation, but the population of the young low-mass stars remained very poorly studied until recently. Aims. Our aim was to produce a near-infrared survey that is deep enough to detect the full low-mass stellar population (i.e. down to ≈0.1 M and for extinctions up to A V ≈ 15 mag) and wide enough to cover all important parts of the Carina Nebula complex (CNC), including the clusters Tr 14, 15, and 16 as well as the South Pillars region. Methods. We used HAWK-I at the ESO VLT to survey the central ≈0.36 deg 2 area of the Carina Nebula. These data reveal more than 600 000 individual infrared sources down to magnitudes as faint as J ≈ 23, H ≈ 22, and K s ≈ 21. The results of a recent deep X-ray survey (which is complete down to stellar masses of ∼0.5−1 M ) are used to distinguish between young stars in Carina and background contaminants. We analyze color−magnitude diagrams (CMDs) to derive information about the ages and masses of the low-mass stars.Results. The ages of the low-mass stars agree with previous age estimates for the massive stars. The CMD suggests that ≈3200 of the X-ray selected stars have masses of M * ≥ 1 M ; this number is in good agreement with extrapolations of the field IMF based on the number of high-mass (M * ≥ 20 M ) stars and shows that there is no deficit of low-mass stars in the CNC. The HAWK-I images confirm that about 50% of all young stars in Carina are in a widely distributed, non-clustered spatial configuration. Narrowband images reveal six molecular hydrogen emission objects (MHOs) that trace jets from embedded protostars. However, none of the optical HH objects shows molecular hydrogen emission, suggesting that the jet-driving protostars are located very close to the edges of the globules in which they are embedded. Conclusions. The near-infrared excess fractions for the stellar population in Carina are lower than typical for other, less massive clusters of similar age, suggesting that the process of circumstellar disk dispersal proceeds on a faster timescale in the CNC than in the more quiescent regions, most likely due to the very high level of massive star feedback in the CNC. The location of all but one of the known jet-driving protostars at the edges of the globules adds strong support to the scenario that their formation was triggered by the advancing ionization fronts.

Herschelfar-infrared observations of the Carina Nebula complex

“…We note that Lada et al (2010) have demonstrated a good correlation between the gas mass above A V > 7 and the star formation rate, that seems to be valid over a very wide range of cloud masses. This relation predicts a star formation rate of the order 10 −3 M yr −1 for the CNC, which is well consistent with the integrated mass and age distribution of the young stars that have formed recently in these clouds (see Preibisch et al 2011c).…”

“…We note that this region contains the cluster Tr 15 and Bo 10, which have estimated ages of 7−8 Myr (Dias et al 2002;Preibisch et al 2011c) and are thus several Myr older than the clusters Tr 14 and Tr 16 in the center of the Carina Nebula. This could suggest that at this older age, the stellar-wind feedback (especially from the evolved massive stars) may play an important role.…”

“…Among these are several of the most massive (M > ∼ 100 M ) and luminous stars known in our Galaxy, e.g., the famous luminous blue variable η Car, the O2 If* star HD 93129Aa, several O3 main sequence stars, and four Wolf-Rayet stars. Most of the A&A 541, A132 (2012) massive stars reside in several loose clusters near the center of the complex, including Tr 14, 15, and 16, which have ages ranging from <1 to ∼8 Myr (see Dias et al 2002;Preibisch et al 2011c). The CNC contains large amounts of gas and dust clouds, with an estimated total mass in the range 350 000−670 000 M based on CO radio maps (e.g.…”

“…We have performed a very deep near-infrared survey of the central ∼1300 square-arcminute area of the CNC with the nearinfrared camera HAWK-I at the ESO 8m-VLT (Preibisch et al 2011c) which is deep enough to reveal all young stars in the region with A V ≤ 35 mag.…”

Detection of a large massive circumstellar disk around a high-mass young stellar object in the Carina Nebula

“…The near-infrared data presented in this paper were obtained in the context of our large survey of the Carina Nebula (see Preibisch et al 2011c, for more details) with the instrument HAWK-I (see Kissler-Patig et al 2008) at the ESO 8 m Very Large Telescope. HAWK-I is equipped with a mosaic of four Hawaii 2RG 2048 × 2048 pixel detectors with a scale of 0.106 per pixel.…”