The triple evolution dynamical instability: Stellar collisions in the field and the formation of exotic binaries

Abstract

Physical collisions and close approaches between stars play an important role in the formation of exotic stellar systems. Standard theories suggest that collisions are rare, occurring only via random encounters between stars in dense clusters. We present a different formation pathway, the triple evolution dynamical instability (TEDI), in which mass loss in an evolving triple star system causes orbital instability. The subsequent chaotic orbital evolution of the stars triggers close encounters, collisions, exchanges between the stellar components, and the dynamical formation of eccentric compact binaries (including Sirius like binaries). We demonstrate that the rate of stellar collisions due to the TEDI is approximately 10^{-4} yr^{-1} per Milky-Way Galaxy, which is nearly 30 times higher than the total collision rate due to random encounters in the Galactic globular clusters. Moreover, we find that the dominant type of stellar collisions is qualitatively different; most collisions involve asymptotic giant branch stars, rather than main sequence, or slightly evolved stars, which dominate collisions in globular clusters. The TEDI mechanism should lead us to revise our understanding of collisions and the formation of compact, eccentric binaries in the field.

Restructured; now matching published ApJ version

References in corpus (12)

• An Eccentric Binary Millisecond Pulsar in the Galactic Plane
• Comparative statistics and origin of triple and quadruple stars
• Orbital eccentricities of binary systems with a former AGB star
• Runaway and hypervelocity stars in the Galactic halo: Binary rejuvenation and triple disruption
• Eccentric double white dwarfs as LISA sources in globular clusters
• Common Powering Mechanism of Intermediate Luminosity Optical Transients and Luminous Blue Variables
• Second generation planets
• Galactic Kinematics from OB3 Stars with Distances determined from Interstellar Ca II Lines
• Searching for Possible Siblings of the Sun from a Common Cluster based on Stellar Space Velocities
• Clearing the Dust from Globular Clusters
• Tidal Interactions of Red Giants with Environment Stars in Globular Clusters
• Post-AGB Stars with Circumbinary Discs