The Nature of the Variable Galactic Center Source GCIRS 16SW Revisited: A Massive Eclipsing Binary

Peeples, Molly S.; Bonanos, A. Z.; DePoy, D. L.; Stanek, K. Z.; Pepper, Joshua; Pogge, Richard W.; Pinsonneault, Marc H.; Sellgren, K.

doi:10.1086/510720

Cited by 12 publications

(12 citation statements)

References 23 publications

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“…Finally both stars within the eclipsing contact binary GC IRS16SW (2×Ofpe/WNLh; Martins et al 2006b) share similar spectral morphologies to LHO110. Peeples et al (2007) derive dynamical masses of ∼ 50M ⊙ for both components of GC IRS16SW; compatible with Gr14 if they are indeed evolving from a B-hypergiant to an LBV phase.…”

Section: Corroboration -Luminosities and Masses Of Cluster Memberssupporting

confidence: 70%

An updated stellar census of the Quintuplet cluster

Clark

Lohr

Patrick

et al. 2018

A&A

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Context. The Quintuplet is one of the most massive young clusters in the Galaxy. As a consequence it offers the prospect of constraining stellar formation and evolution in extreme environments. However, current observations suggest that it comprises a remarkably diverse stellar population that is difficult to reconcile with an instantaneous formation event. Aims. To better understand the nature of the cluster we aim to improve observational constraints on the constituent stars. Methods. In order to accomplish this goal we present HST/NICMOS+WFC3 photometry and VLT/SINFONI+KMOS spectroscopy for ∼ 100 and 71 cluster members, respectively. Results. The Quintuplet appears far more homogeneous than previously expected. All supergiants are classified as either O7-8 Ia or O9-B0 Ia, with only one object of earlier (O5 I-III) spectral type. These stars form a smooth morphological sequence with a cohort of seven early-B hypergiants and six luminous blue variables and WN9-11h stars, which comprise the richest population of such stars of any stellar aggregate known. In parallel, we identify a smaller population of late-O hypergiants and spectroscopically similar WN8-9ha stars. No further H-free Wolf-Rayet (WR) stars were identified, resulting in a 13:1 ratio for WC/WN stars. A subset of the O9-B0 supergiants are unexpectedly faint, suggesting they are both less massive and older than the greater cluster population. Conclusions. Due to an uncertain extinction law, it is not possible to quantitatively determine a cluster age via isochrone fitting. Nevertheless, we find an impressive coincidence between the properties of cluster members preceding the H-free WR phase and the evolutionary predictions for a single, non-rotating 60M ⊙ star, implying an age of ∼ 3.0 − 3.6Myr. Neither the late O-hypergiants nor the low luminosity supergiants are predicted by such a path; we suggest that the former either result from rapid rotators or are the products of binary driven mass-stripping, while the latter may be interlopers. The H-free WRs must evolve from stars with an initial mass in excess of 60M ⊙ but it appears difficult to reconcile their observational properties with theoretical expectations. This is important since one would expect the most massive stars within the Quintuplet to be undergoing core-collapse/SNe at this time; since the WRs represent an evolutionary phase directly preceding this event,their physical properties are crucial to understanding both this process and the nature of the resultant relativistic remnant. As such, the Quintuplet provides unique observational constraints on the evolution and death of the most massive stars forming in the local, high metallicity Universe.

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Section: Corroboration -Luminosities and Masses Of Cluster Memberssupporting

confidence: 70%

An updated stellar census of the Quintuplet cluster

Clark

Lohr

Patrick

et al. 2018

A&A

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“…The uncertainty of their results is typically only of the order of a few ×10 per cent, so we did not explore different realizations of the wind data. There is more uncertainty in the wind properties from the 13E group, whose nature is not clearly established yet, and 16SW, which is part of a binary (Martins et al 2006; Peeples et al 2007). The analysis of these sources is not yet robust enough and they are important contributors to the accretion.…”

Section: Discussionmentioning

confidence: 99%

Variable accretion and emission from the stellar winds in the Galactic Centre

Cuadra¹,

Nayakshin²,

Martins³

2007

Monthly Notices of the Royal Astronomical Society

127

201

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We present numerical simulations of stellar wind dynamics in the central parsec of the Galactic Centre, studying in particular the accretion of gas on to Sgr A * , the supermassive black hole. Unlike our previous work, here we use state-of-the-art observational data on orbits and wind properties of individual wind-producing stars. Since wind velocities were revised upwards and non-zero eccentricities were considered, our new simulations show fewer clumps of cold gas and no conspicuous disc-like structure. The accretion rate is dominated by a few close 'slow-wind stars' (v w 750 km s −1 ), and is consistent with the Bondi estimate, but variable on time-scales of tens to hundreds of years. This variability is due to the stochastic infall of cold clumps of gas, as in earlier simulations, and to the eccentric orbits of stars. The present models fail to explain the high luminosity of Sgr A * a few hundred years ago implied by Integral observations, but we argue that the accretion of a cold clump with a small impact parameter could have caused it. Finally, we show the possibility of constraining the total mass-loss rate of the 'slow-wind stars' using near infrared observations of gas in the central few arcseconds.

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“…A small number of binary stars have been identified in the GC (Martins et al 2006; Peeples et al 2007; Rafelski et al 2007), and, given our current knowledge of disc fragmentation, it is possible that the primordial binary fraction resulting from a fragmenting disc could be significant. Encounters between stars and hard binaries tend to shrink the binary orbit, releasing energy that can heat the system (Heggie 1975; Perets, Kupi & Alexander 2008).…”

Section: Simulationsmentioning

confidence: 99%

Stellar dynamical evidence against a cold disc origin for stars in the Galactic Centre

Cuadra

Armitage

Alexander

2008

Monthly Notices of the Royal Astronomical Society: Letters

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Observations of massive stars within the central parsec of the Galaxy show that, while most stars orbit within a well‐defined disc, a significant fraction have large eccentricities and/or inclinations with respect to the disc plane. Here, we investigate whether this dynamically hot component could have arisen via scattering from an initially cold disc – the expected initial condition if the stars formed from the fragmentation of an accretion disc. Using N‐body methods, we evolve a variety of flat, cold, stellar systems, and study the effects of initial disc eccentricity, primordial binaries, very massive stars and intermediate mass black holes. We find, consistent with previous results, that a circular disc does not become eccentric enough unless there is a significant population of undetected 100–1000 M⊙ objects. However, since fragmentation of an eccentric disc can readily yield eccentric stellar orbits, the strongest constraints come from inclinations. We show that none of our initial conditions yields the observed large inclinations, regardless of the initial disc eccentricity or the presence of massive objects. These results imply that the orbits of the young massive stars in the Galactic Centre are largely primordial, and that the stars are unlikely to have formed as a dynamically cold disc.

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The Nature of the Variable Galactic Center Source GCIRS 16SW Revisited: A Massive Eclipsing Binary

Cited by 12 publications

References 23 publications

An updated stellar census of the Quintuplet cluster

An updated stellar census of the Quintuplet cluster

Variable accretion and emission from the stellar winds in the Galactic Centre

Stellar dynamical evidence against a cold disc origin for stars in the Galactic Centre

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