SOAR optical and near-infrared spectroscopic survey of newly discovered massive stars in the periphery of Galactic Massive star clusters I - NGC3603

Abstract

In this work, we present a spectroscopic study of very massive stars found outside the center of the massive stellar cluster NGC3603. From the analysis of SOAR spectroscopic data and related optical-NIR photometry, we confirm the existence of several very massive stars in the periphery of NGC 3603. The first group of objects (MTT58, WR42e and RFS7) is compound by three new Galactic exemplars of the OIf*/WN type, all of them with probable initial masses well above 100 Msun and estimated ages of about 1 Myr. Based on Goodman blue-optical spectrum of MTT68, we can confirm the previous finding in the NIR of the only other Galactic exemplar (besides HD93129A) of the O2If* type known to date. Based on its position relative to a set of theoretical isochrons in a Hertzprung-Russel diagram, we concluded that the new O2If* star could be one of the most massive (150 Msun) and luminous (Mv=-7.3) O-star in the Galaxy. Also, another remarkable result is the discovery of a new O2V star (MTT31) that is the first exemplar of the class so far identified in the Milk Way. From its position in the Hertzprung-Russel diagram it is found that this new star probably had an initial mass of 80 Msun, as well as an absolute magnitude Mv=-6.0 corresponding to a luminosity similar to other known O2V stars in the LMC. We also communicate the discovery of a new Galactic O3.5If* star (RFS8) which case is quite intriguing. Indeed, It is located far to the south of the NGC 3603 center, in apparent isolation at a large radial projected linear distance of 62 pc. Its derived luminosity is similar to that of the other O3.5If* (Sh18) found in the NGC 3603's innermost region. The fact that a such high mass star is observed far isolated in the field led us to speculate that perhaps it could have been expelled from the innermost parts of the complex by a close fly-by dynamical encounter with a very massive hard binary system.

36 pages, 9 figures and 5 tables. Accepted for publication in the Astrophysical Journal

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Cited by in corpus (14)

• Final Targeting Strategy for the SDSS-IV APOGEE-2N Survey
• Spectroscopic evolution of massive stars on the main sequence
• The Villafranca catalog of Galactic OB groups: I. Systems with O2-O3.5 stars
• The deep OB star population in Carina from the VST Photometric H$\alpha$ Survey (VPHAS+)
• The O star hinterland of the Galactic starburst, NGC 3603
• A VLT/FLAMES survey for massive binaries in Westerlund 1: VII. Cluster census
• Massive stars in the SDSS-IV/APOGEE SURVEY. I- OB stars
• The Arches cluster revisited. III. An addendum to the stellar census
• Did a stellar fly-by shape the planetary system around Pr 0211 in the cluster M 44?
• The blue supergiant Sher 25 revisited in the Gaia era
• On the origin of very massive stars around NGC 3603
• Radial velocities from far red spectra of Carina Arm O and early B stars
• Sapaki: Galactic O3If* star possibly born in isolation
• Winds of Massive Stars: High Resolution X-ray Spectra of Stars in NGC 3603