http://arxiv.org/abs/2112.11475
Recent surveys show that wide (>10^4 AU) binaries and triples are abundant in the field. We study the long-term evolution of wide hierarchical triple systems and the role played by the Galactic tidal field. We find that when the timescales of the secular von-Ziepel-Lidov-Kozai and the galactic tide oscillations are comparable, the triple evolution becomes chaotic and extreme eccentricities can be attained. Consequently, the close pericentre approaches of the inner-binary components lead to strong interactions, and even mergers or collisions. We use a novel secular evolution code to quantify the key parameters of triple evolution coupled to the galactic tide, and carry out a population synthesis study of low and intermediate-mass wide-orbit triples. We find that in ~9% of low-mass wide-triples the inner main-sequence binaries collide or tidally-inspiral within 10 Gyr, with direct collisions six times more likely to occur than inspirals. For the intermediate-mass sample, ~7.6 of the systems merge or inspiral with roughly equal probabilities. We find the relative fractions of different outcomes as a function of their evolutionary stage (Main Sequence, MS; Red Giant, RG; or White Dwarf, WD), and discuss their transient electromagnetic signatures and the products of the merger/inspiral. In particular, we find the rate of WD-WD direct-collisions that lead to thermonuclear type-Ia Supernovae is comparable to other dynamical channels, and accounts for at most 0.1% of the total rate. RG inspirals provide a novel channel for the formation of eccentric common-envelope-evolution binaries. We also find that the catalysis of mergers/collisions in triples due to the galactic tide could explain a significant fraction or even the vast majority of blue-stragglers in the field, producing progenitors for cataclysmic-variables, and give-rise to mergers and collisions of double-RG binaries.
E. Grishin and H. Perets
Thu, 23 Dec 21
31/63
Comments: Comments are welcome