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تسجيل مستخدم جديدThe Chandra Carina Complex Project View of Trumpler 16
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Trumpler 16 is a well--known rich star cluster containing the eruptive supergiant $eta$ Carinae and located in the Carina star-forming complex. In the context of the Chandra Carina Complex Project, we study Trumpler 16 using new and archival X-ray data. A revised X-ray source list of the Trumpler 16 region contains 1232 X-ray sources including 1187 likely Carina members. These are matched to 1047 near-infrared counterparts detected by the HAWK-I instrument at the VLT allowing for better selection of cluster members. The cluster is irregular in shape. Although it is roughly circular, there is a high degree of sub-clustering, no noticeable central concentration and an extension to the southeast. The high--mass stars show neither evidence of mass segregation nor evidence of strong differential extinction. The derived power-law slope of the X-ray luminosity function for Trumpler 16 reveals a much steeper function than the Orion Nebula Cluster implying different ratio of solar- to higher-mass stars. We estimate the total Trumpler 16 pre-main sequence population to be > 6500 Class II and Class III X-ray sources. An overall K-excess disk frequency of ~ 8.9% is derived using the X-ray selected sample, although there is some variation among the sub-clusters, especially in the Southeastern extension. X-ray emission is detected from 29 high--mass stars with spectral types between B2 and O3.
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We present the first extensive spectroscopic study of the global population in star clusters Trumpler~16, Trumpler~14 and Collinder~232 in the Carina Nebula, using data from the Gaia-ESO Survey, down to solar-mass stars. In addition to the standard h
omogeneous Survey data reduction, a special processing was applied here because of the bright nebulosity surrounding Carina stars. We find about four hundred good candidate members ranging from OB types down to slightly sub-solar masses. About one-hundred heavily-reddened early-type Carina members found here were previously unrecognized or poorly classified, including two candidate O stars and several candidate Herbig Ae/Be stars. Their large brightness makes them useful tracers of the obscured Carina population. The spectroscopically-derived temperatures for nearly 300 low-mass members allows the inference of individual extinction values, and the study of the relative placement of stars along the line of sight. We find a complex spatial structure, with definite clustering of low-mass members around the most massive stars, and spatially-variable extinction. By combining the new data with existing X-ray data we obtain a more complete picture of the three-dimensional spatial structure of the Carina clusters, and of their connection to bright and dark nebulosity, and UV sources. The identification of tens of background giants enables us also to determine the total optical depth of the Carina nebula along many sightlines. We are also able to put constraints on the star-formation history of the region, with Trumpler~14 stars found to be systematically younger than stars in other sub-clusters. We find a large percentage of fast-rotating stars among Carina solar-mass members, which provide new constraints on the rotational evolution of pre-main-sequence stars in this mass range.
In this paper we present and analyze new CCD $UBVRI$ photometry down to $V approx$ 21 in the region of the young open cluster Collinder 232, located in the Carina spiral arm, and discuss its relationship to Trumpler 14 and Trumpler 16, the two most p
rominent young open clusters located in the core of NGC 3372 (the Carina Nebula). First of all we study the extinction pattern in the region. We find that the total to selective absorption ratio $R_V$ differs from cluster to cluster, being $3.48pm0.11$, $4.16pm0.07$ and $3.73pm0.01$ for Trumpler 16, Trumpler 14 and Collinder 232, respectively. Then we derive individual reddenings and intrinsic colours and magnitudes using the method devised by Romaniello et al. (2002). Ages, age spreads and distances are then estimated by comparing the Colour Magnitude Diagrams and the Hertzsprung-Russel diagram with post and pre-main sequence tracks and isochrones. We find that Trumpler 14 and Collinder 232 lie at the same distance from the Sun (about 2.5 kpc), whereas Trumpler 16 lies much further out, at about 4 kpc from the Sun. As for the age, we find that Trumpler 16 is older than both Trumpler 14 and Collinder 232. For all the clusters we indicate the existence of a significant age dispersion, whose precise value is hampered by our inability to properly distinguish members from non-members. We finally suggest that Collinder 232 is a physical aggregate and provide estimates of its basic parameters.
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 arcsec across the 2 arcmin 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 1E+05 yr, confirming the very young age of the cluster. We derive a very high (deprojected) central density n0~4.5(+/-0.5) times 10^4 pc^-3 and estimate the total mass of the cluster to be about ~4.3^{+3.3}_{-1.5} times 10^3 Msun, 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 arcsec (~1300AU). We further show that at the 2-sigma 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 Msun. If confirmed, the observed degree of mass segregation could be explained by dynamical evolution, despite the young age of the cluster.
Gaia parallaxes for the star cluster Tr 16 reveal a discrepancy in the oft-quoted distance of Eta Carinae. It is probably more distant and more luminous. Moreover, many presumed members may not belong to Tr 16.
Using offset-corrected Gaia-EDR3 parallax measurements and spectrophotometric methods, we have determined distances for 69 massive stars in the Carina OB1 association and associated clusters: Trumpler 16 (21 stars), Trumpler 14 (20 stars), Trumpler 1
5 (3 stars), Bochum 11 (5 stars), and South Pillars region (20 stars). Past distance estimates to the Carina Nebula range from 2.2 to 3.6 kpc, with uncertainties arising from photometry and anomalous dust extinction. The EDR3 parallax solutions show considerable improvement over DR2, with typical errors $sigma_{varpi}/varpi approx$~3-5%. The O-type stars in the Great Carina Nebula lie at essentially the same distance ($2.35pm0.08$ kpc), quoting mean and rms variance. The clusters have distances of $2.32pm0.12$ kpc (Tr 16), $2.37pm0.15$ kpc (Tr 14), $2.36pm0.09$ kpc (Tr 15), and $2.33pm0.12$ kpc (Bochum 11) in good agreement with the $eta$ Car distance of around 2.3 kpc. O-star proper motions suggest internal (2D) velocity dispersions $sim4$ km/s for Tr 14 and Tr 16. Reliable distances allow estimates of cluster sizes, stellar dynamics, luminosities, and fluxes of photoionizing radiation incident on photodissociation regions in the region. We estimate that Tr 14 and Tr 16 have half-mass radii $r_h = 1.5-1.8$ pc, stellar crossing times $t_{rm cr} = r_h/v_m approx 0.7-0.8$ Myr, and two-body relaxation times $t_{rh} approx 40-80$ Myr. The underlying velocity dispersion for Tr 14, if a bound cluster, would be $v_m approx 2.1^{+0.7}_{-0.4}$ km/s for $N = 7600^{+5800}_{-2600}$ stars. With the higher dispersions of the O-stars, mass segregation might occur slowly, on times scales of 3-6~Myr.
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