Binary interactions with high accretion rates onto main sequence stars

Abstract

Energetic outflows from main sequence stars accreting mass at very high rates might account for the powering of some eruptive objects, such as merging main sequence stars, major eruptions of luminous blue variables, e.g., the Great Eruption of Eta Carinae, and other intermediate luminosity optical transients (ILOTs; Red Novae; Red Transients). These powerful outflows could potentially also supply the extra energy required in the common envelope process and in the grazing envelope evolution of binary systems. We propose that a massive outflow/jets mediated by magnetic fields might remove energy and angular momentum from the accretion disk to allow such high accretion rate flows. By examining the possible activity of the magnetic fields of accretion disks we conclude that indeed main sequence stars might accrete mass at very high rates, up to ≈ 10 −2 M ⊙ yr −1 for solar type stars, and up to ≈ 1M ⊙ yr −1 for very massive stars. We speculate that magnetic fields amplified in such extreme conditions might lead to the formation of massive bipolar outflows that can remove most of the disk's energy and angular momentum. It is this energy and angular momentum removal that allows the very high mass accretion rate on to main sequence stars.

The jet feedback mechanism (JFM) in stars, galaxies and clusters

“…(3) To have sufficiently strong jets, the companion must accrete at a high rate. Recent results support the notion that main sequence stars can accrete mass at a high rate through an accretion disk or an accretion belt (Shiber et al 2016;Staff et al 2016a). The 3-dimensional hydrodynamical simulations conducted by Staff et al (2016a) are very constructive in demonstrating that a main sequence companion can indeed accrete mass at a high rate, ≈ 0.01M ⊙ yr −1 , and might form a thick accretion disk when orbiting close to and outside a giant envelope.…”

“…This holds for main sequence stars as well , as they can accrete mass at a high rate (Shiber et al 2016). Armitage & Livio (2000) and Chevalier (2012) study CE ejection by jets launched from a NS companion, but they did not consider jets to be a general common envelope ejection process.…”

“…MacLeod & Ramirez-Ruiz 2015). The removal of energy and high-entropy gas by the jets reduces the pressure near the accreting star, hence eases the accretion process and allows high accretion rates (Shiber et al 2016;Staff et al 2016a), and the formation of an accretion disk or belt. Ricker & Taam (2012), for example, find the mass accretion rate onto the secondary star in their simulation of the CEE to be much below the one given by the Bondi-Hoyle-Lyttleton (BHL) prescription.…”

Grazing envelope evolution towards Type IIb supernovae

“…Ricker & Taam 2012;MacLeod & Ramirez-Ruiz 2015). The jets remove high-entropy gas, as well as angular momentum and energy, from the vicinity of the accreting companion, hence reducing the pressure around the companion (Shiber et al 2016;Staff et al 2016a).…”

Energizing the last phase of common-envelope removal

“…There is also a positive feedback effect. The jets remove angular momentum, high-entropy gas, and energy from the vicinity of the accreting secondary star, and by that reduce the pressure and allow the accretion (Shiber et al 2016;Staff et al 2016a), most likely through an accretion disk or an accretion belt. If not for this positive feedback effect, accretion would be much lower due to the build up of a high pressure in the vicinity of the accreting secondary star (e.g.…”