Binary interactions with high accretion rates onto main sequence stars

TL;DR

This paper explores how magnetic fields can enable main sequence stars to accrete mass at very high rates, powering energetic outflows that may explain phenomena like stellar mergers and luminous blue variable eruptions.

Contribution

It proposes a magnetic outflow mechanism that allows main sequence stars to sustain extremely high accretion rates, a novel concept in stellar accretion physics.

Findings

Magnetic fields can facilitate accretion rates up to 0.01 solar masses per year for solar-type stars.

Massive bipolar outflows may form, removing energy and angular momentum from the accretion disk.

High accretion rates could power energetic stellar eruptions and outflows.

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 ~0.01 Mo/yr for solar type stars, and up to ~1 Mo/yr 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.