An O2If*/WN6 Star Catch in the Act in a Compact Hii region in the Starburst Cluster NGC 3603

TL;DR

This paper reports the discovery of a very young, massive O2If*/WN6 star in NGC 3603, with detailed analysis of its properties, age, and mass estimates, highlighting its significance in understanding massive star formation.

Contribution

It presents the first identification and characterization of an O2If*/WN6 star still embedded in its natal environment in NGC 3603, with detailed physical and evolutionary parameters.

Findings

Star likely less than 600,000 years old

Initial mass estimates exceed 80-100 solar masses

Bolometric luminosity around 8x10^5 Lsun

Abstract

In this paper I report the discovery of an O2If*/WN6 star probably still partially embedded in its parental cocoon in the star-burst cluster NGC 3603. From the observed size of the associated compact Hii region, it was possible to derive a probable dynamic age of no more than 600,000 years. Using the computed visual extinction value Av ~ 6 magnitudes, an absolute visual magnitude Mv =-5.7 mag is obtained, which for the assumed heliocentric distance of 7.6 kpc results in a bolometric luminosity of ~ 8x10^5 Lsun. Also from the V magnitude and the V-I color of the new star, and previous models for NGC3603's massive star population, we estimate its mass for the binary (O2If*/WN6 + O3If) and the single-star case (O2If*/WN6). In the former, it was found that the initial mass of each component possibly exceeded 80 Msun and 40 Msun, while in the latter MTT 58's initial mass possibly was in excess of 100 Msun.