Identifying stars of mass >150 M⊙ from their eclipse by a binary companion

Abstract

We examine the possibility that very massive stars greatly exceeding the commonly adopted stellar mass limit of 150M ⊙ may be present in young star clusters in the local universe. We identify ten candidate clusters, some of which may host stars with masses up to 600M ⊙ formed via runaway collisions. We estimate the probabilities of these very massive stars being in eclipsing binaries to be 30%. Although most of these systems cannot be resolved at present, their transits can be detected at distances of 3 Mpc even under the contamination of the background cluster light, due to the large associated luminosities ∼ 10 7 L ⊙ and mean transit depths of ∼ 10 6 L ⊙ . Discovery of very massive eclipsing binaries would flag possible progenitors of pair-instability supernovae and intermediate-mass black holes.

The Evolution of Compact Binary Star Systems

“…3The existence of such high-mass very short-living objects is deemed possible due to runaway stellar collisions in dense young compact stellar clusters [605]; for the prospects of observing them see, e.g., [564]. …”

Probing Intermediate Mass Black Holes in M87 through Multi-Wavelength Gravitational Wave Observations

“…Stellar-mass BHs are most abundant, with observational evidence first detected in X-rays (Webster & Murdin 1972;Remillard & Mc-Clintock 2006), and more recently by gravitational waves (GWs) with LIGO/Virgo (Abbott et al 2016a,b). Intermediate mass black holes (IMBHs) are expected to form from the accretion of gas in dwarf galaxies (see (Reines et al 2019) and references therein), mergers of stars in dense stellar clusters (Portegies Zwart et al 1999;Devecchi & Volonteri 2009;Pan & Loeb 2012;Mapelli 2016), from direct collapse of inflowing dense gas in protogalaxies (Loeb & Rasio 1994), collapse of Pop III stars from early universe (Madau & Rees 2001;Bromm & Larson 2004) or from supermassive stars in AGN accretion disk instabilities (McKernan et al 2012(McKernan et al , 2014.…”

Eclipsing Stellar Binaries in the Galactic Center

“…Specifically, in the case when the stellar binary orbit is circular and isotropically distributed (cos(i * ) uniformly distributed), the eclipse probability is (R 1 + R 2 )/a, where R 1 and R 2 are the stellar radii (e.g., Pan & Loeb 2012), as illustrated in Figure 1. Using this expression, we obtain the eclipse probability of SO-2 as a function of stellar mass ratio q, assuming a total mass for the stellar binary is 15M (shown in Figure 3).…”