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Publication . Article . Preprint . 2021

Chaotic dynamics of wide triples induced by galactic tides: a novel channel for producing compact binaries, mergers, and collisions

Evgeni Grishin; Hagai B Perets;
Open Access
Published: 21 Dec 2021 Journal: Monthly Notices of the Royal Astronomical Society, volume 512, pages 4,993-5,009 (issn: 0035-8711, eissn: 1365-2966, Copyright policy )
Publisher: Oxford University Press (OUP)
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 (GT) field. We find that when the timescales of the secular von-Ziepel-Lidov-Kozai and the GT oscillations are comparable, triple evolution becomes chaotic which leads to extreme eccentricities. Consequently, the close pericentre approaches of the inner-binary components lead to strong interactions, mergers and collisions. We use a novel secular evolution code to quantify the key parameters and carry out a population-synthesis study of low and intermediate-mass wide-orbit triples. We find that in $\sim9\%$ of low-mass wide-triples the inner main-sequence binaries collide or tidally-inspiral within $10\ \rm Gyr$, with direct collisions are $6$ times more likely to occur. For the intermediate-mass sample, $\sim7.6\%$ of the systems merge or inspiral with roughly equal probabilities. We discuss the relative fractions of different stellar merger/inspiral outcomes as a function of their evolutionary stage (Main-Sequence, MS; Red-Giant, RG; or White-Dwarf, WD), their transient electromagnetic signatures and the final products of the merger/inspiral. In particular, the rate of WD-WD direct-collisions that lead to type-Ia Supernovae is comparable to other dynamical channels and accounts for at most $0.1\%$ of the observed rate. RG inspirals provide a novel channel for the formation of eccentric common-envelope-evolution binaries. The catalysis of mergers/collisions in triples due to GT could explain a significant fraction, or even the vast majority, of blue-stragglers in the field, produce progenitors for cataclysmic-variables, and give-rise to mergers/collisions of double-RG binaries.
Accepted to MNRAS
Subjects by Vocabulary

arXiv: Astrophysics::Galaxy Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics::Earth and Planetary Astrophysics Astrophysics::Solar and Stellar Astrophysics


Space and Planetary Science, Astronomy and Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics of Galaxies (astro-ph.GA), High Energy Astrophysical Phenomena (astro-ph.HE), FOS: Physical sciences, Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics - High Energy Astrophysical Phenomena

Funded by
The origins of thermonuclear supernova explosions
  • Funder: European Commission (EC)
  • Project Code: 865932
  • Funding stream: H2020 | ERC | ERC-COG
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