An O2If* star found in isolation in the backyard of NGC 3603

Abstract

In this letter we communicate the identification of a new Galactic O2If* star (MTT 68) isolated at a projected linear distance of 3 pc from the centre of the star-burst cluster NGC 3603. From its optical photometry I computed a bolometric luminosity M_Bol = -10.7, which corresponds to a total stellar luminosity of 1.5 x 10^{6} L_Sun. It was found an interesting similarity between MTT 68 and the well known multiple system HD 93129. From Hubble Space Telescope F656N images of the NGC 3603 field, it was found that MTT 68 is actually a visual binary system with an angular separation of 0.38 arcsec, which corresponds to a projected (minimum) linear distance of r_(A-B) = 1.4 x 10^{-2} pc. This value is similar to that for the HD 93129A (O2If*) and HD 93129B (O3.5) pair, r_(A-B) = 3.0 x 10^{-2} pc. On the other hand, HD93129A has a third closer companion named HD 93129Ab (O3.5) at only 0.053 arcsec, and taking into account that the X-ray to total stellar luminosity ratio for the MTT 68 system (L_X/L_Bol 10^{-5}) is about two orders of magnitude above the canonical value expected for single stars, I suspect that the MTT 68 system probably hosts another massive companion not resolved by the HST archive images.

5 pages, 4 figures, accepted for publication on MNRAS letters

References in corpus (3)

• The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 Msun stellar mass limit
• On the role of the WNH phase in the evolution of very massive stars: Enabling the LBV instability with feedback
• An O2If*/WN6 Star Catch in the Act in a Compact Hii region in the Starburst Cluster NGC 3603

Cited by in corpus (10)

• Dynamical ejections of massive stars from young star clusters under diverse initial conditions
• The Massive Star-forming Regions Omnibus X-ray Catalog
• The Villafranca catalog of Galactic OB groups: I. Systems with O2-O3.5 stars
• SOAR optical and near-infrared spectroscopic survey of newly discovered massive stars in the periphery of Galactic Massive star clusters I - NGC3603
• Spectral classification of B stars: The empirical sequence using SDSS-IV/APOGEE near-IR data
• Massive stars in the giant molecular cloud G23.3-0.3 and W41
• Massive stars in the SDSS-IV/APOGEE SURVEY. I- OB stars
• Winds of Massive Stars: High Resolution X-ray Spectra of Stars in NGC 3603
• Sapaki: Galactic O3If* star possibly born in isolation
• Kinematics of the Central Stars Powering Bowshock Nebulae and the Large Multiplicity Fraction of Runaway OB Stars