Imaging study of NGC 3372, the Carina nebula - III. The properties of G287.47−0.54 (Tr 14-N4), an embedded young cluster and its associated H2 emission★

Abstract

New deep broad‐ and narrow‐band (JHK and Br γ at 2.17 μm and H2 at 2.12 μm) near‐infrared (near‐IR) images of the mid‐IR source G287.47−0.54 (Tr14‐N4) taken with the Baade Magellan telescope are presented and analysed along with archive 3.6–8 μ m Spitzer images. The analysis of these data demonstrates the presence of a compact (r∼ 23 arcsec, 0.3 pc), embedded IR cluster with at least 72 young members. The colour–magnitude diagram of the cluster suggests an age of approximately 105 years, consistent with the large fraction (≥32 per cent) of embedded sources found to show significant excess emission at λ > 2 μ m. The two youngest and most luminous sources are located close to the cluster nucleus. The properties of their spectral energy distributions (SEDs) indicate that these are Class I young stellar objects (YSOs) with masses in the range 7–9 M⊙ and luminosities between 400 and 800 L⊙. We derive the presence of a tilted (i∼ 40°–70°) disc of size ≥0.05 pc around one of these YSOs, #902. This object is seen directly through the dust disc only at λ≥ 2.2, with most of the observed near‐IR radiation being scattered light from lobes on both sides of the disc. In contrast, the second bright YSO, #438, is seen directly even in the near‐IR and also shows symmetrically elongated features that seem to be caused by scattering. The young cluster G287.47−0.54 is embedded at the head of a dust pillar and is another example of a photodissociation region (PDR) where triggered star formation occurs as a consequence of the interaction of a very massive developed cluster, in this case Tr 16, with a dense molecular core. It appears that the dense cloudlet is sticking out of the remnant giant molecular cloud located at the far side of the northern Carina nebula. Five small molecular hydrogen emission knots at 2.12 μ m with no Brγ counterpart are found in the vicinity of a CO peak, some 0.4 pc north‐west of the cluster nucleus. Most probably, these are shock excited, suggesting the presence of mass outflows in the region. At present, it is unclear whether the engine of this outflow is a member of the cluster or rather it is an undetected, younger YSO deeply embedded in the molecular core.

The Mysterious Sickle Object in the Carina Nebula: A Stellar Wind Induced Bow Shock Grazing a Clump?

“…In the molecular hydrogen line narrow-band image the relative brightness of the Sickle nebula is not much larger than in the broad-band image, but the nebulosity seems to be slightly more extended at the north-western edge. This suggests moderate amounts of molecular hydrogen line emission at the front of the nebula, similar as often observed in the bow-shocks of protostellar jets that move through molecular clouds (Preibisch et al 2011d;Tapia et al 2011). 2007) stated a detection limit of 0.4 mJy.…”

A Survey of Irradiated Pillars, Globules, and Jets in the Carina Nebula

“…The bright K-band source labeled IRS in Fig. 10 is a massive star embedded within a nearly edge-on circumstellar disk that Preibisch et al (2011d) refer to as the 'disk object' (also known as source #902, Tapia et al 2011). A separate foreground X-ray source, PCYC 556, is located about 2 arcseconds to the southeast of the near-IR peak, and appears in our near-IR images and those of Preibisch et al (2011d) as a distinct point source.…”

“…Cr 232/N4 Area, MHO 1606 − 1608 : Preibisch et al (2011b) and Tapia et al (2011) discussed the cluster Cr 232 that is associated with the extended H 2 emission in Area 33 of Fig. 10.…”

“…In the optical, Grenman & Gahm (2014) compiled a list of dozens of small dark globules in Carina from archival HST Hα images of the central portion of the Carina star formation region. Tapia et al (2011) has published H 2 2.12µm images of selected objects within Carina, and Ohlendorf et al (2012) discuss mid-IR Spitzer images of the region whose filters include lines of H 2 .…”

Dependency of Dynamical Ejections of O Stars on the Masses of Very Young Star Clusters

“…However, caution is due in directly comparing the model cluster densities to the observed values since the observed densities are closer to the central (i.e., highest) densities rather than to the half-mass density. Concerning the initial radii of the embedded clusters, these are dynamically sub-pc (Testi et al 1999;Lada & Lada 2003;Kroupa 2005;Smith et al 2005;Tapia et al 2009Tapia et al , 2011Tapia et al , 2014.…”