The Formation Process of Massive Close Spectroscopic Binaries: The Fission Hypothesis Revisited

The vast majority of massive Main-Sequence stars (M>20 Mo) seem to be born in close interactive binary systems (Chini et al. 2012, Sana et al. 2012). The very process by which these systems form is still a mystery and has received little attention so far. Because the binary separation is so tight (less than 1AU), break-up of a critically rotating protostar ("fission") remains an interesting possibility. However, standard current star formation theory treats fission as unlikely (cf. Tohline 2002, ARAA). We question this view and investigate minimum energy states of compressible polytropic analogs to the well-known incompressible MacLaurin spheroids. Dynamical non-axisymmetric instability at a critical ratio of rotational to gravitational energy (cf. Ostriker and Bodenheimer 1973) during the shrinkage of an accreting, rapidly rotating, bloated, massive protostar AFTER ACCRETION DECLINES may provide the conditions for break-up into a close binary system. Time dependent hydro-dynamical simulations are required to either confirm or reject this hypothesis.