Formation pathways and survival of wide NS+MS binaries

Determine the evolutionary pathways and physical processes that allow binaries consisting of a solar-type main-sequence star and a dark companion with mass near 1.4 solar masses, as identified by Gaia DR3 astrometric solutions and radial-velocity follow-up, to avoid merger or dramatic orbital shrinkage during the red-supergiant phase of the neutron-star progenitor and to remain bound after neutron-star formation despite supernova mass loss and natal kicks.

Background

The paper reports 21 astrometric binaries with solar-type primaries and dark companions with masses near 1.4 solar masses, consistent with dormant neutron stars. Their orbits are wide (periods roughly 100–1000 days) and often eccentric, and the systems show properties suggestive of survival through both a red-supergiant phase and a supernova event.

The authors highlight that standard binary evolution would tend to lead to merger or strong orbital shrinkage during the red-supergiant phase and to binary disruption during the supernova due to mass loss and natal kicks. Understanding how these systems avoided both outcomes is central to explaining their formation history.