Chandra X-ray observation of the young stellar cluster NGC 3293 in the Carina Nebula Complex

TL;DR

This study uses deep Chandra X-ray observations to characterize the stellar population of NGC 3293, revealing a large, young, and normally distributed population of stars, and refuting previous claims of a deficit of lower-mass stars.

Contribution

It provides the first comprehensive X-ray analysis of NGC 3293, confirming a normal initial mass function and detailed age estimation, and highlights the cluster's significance within the Carina Nebula Complex.

Findings

Detected 1026 X-ray sources, 74% with infrared counterparts.

Refuted claims of a lack of stars with M <= 2.5 M_sun.

Estimated cluster age of approximately 8-10 million years.

Abstract

We characterize the stellar population of the poorly explored young stellar cluster NGC 3293 at the northwestern periphery of the Carina Nebula Complex, in order to evaluate the cluster age and the mass function, and to test claims of an abnormal IMF and a deficit of M <= 2.5 M_sun stars. We performed a deep (70 ksec) X-ray observation of NGC 3293 with Chandra and detected 1026 individual X-ray point sources. We identify counterparts for 74% of the X-ray sources in deep near-infrared images. Our data clearly show that NGC 3293 hosts a large population of solar-mass stars, refuting claims of a lack of M <= 2.5 M_sun stars. The analysis of the color magnitude diagram suggests an age of ~8-10 Myr for the low-mass population of the cluster. There are at least 511 X-ray detected stars with color magnitude positions that are consistent with young stellar members within 7 arcmin of the cluster center. The number ratio of X-ray detected stars in the 1-2 M_sun range versus the M >= 5 M_sun stars (known from optical spectroscopy) is consistent with the expectation from a normal field initial mass function. Most of the early B-type stars and 20% of the later B-type stars are detected as X-ray sources. Our data shows that NGC 3293 is one of the most populous stellar clusters in the entire Carina Nebula Complex. The cluster probably harbored several O-type stars, whose supernova explosions may have had an important impact on the early evolution of the Carina Nebula Complex.