A census of main-sequence interactions in the Multiple Star Catalogue

Abstract

Statistics of hierarchical systems containing three or more stars are continuously improving. The Multiple Star Catalogue (MSC) is currently the most comprehensive catalogue of multiplestar systems and contains component masses, orbital periods, and additional information. The systems in the MSC are interesting for several reasons, including the long-term dynamical evolution of few-body systems. Although the secular evolution of triples and quadruples has been explored before, a systematic study of the systems in the MSC including also quintuples and sextuples has not been carried out. Here, we explore the main-sequence (MS) evolution of stars from the MSC based on approximately 2 × 10 5 secular dynamical integrations. We estimate statistical probabilities for strong interactions during the MS such as tidal evolution and mass transfer, and the onset of dynamical instability. Depending on the assumed model for the unknown orbital elements, we find that the fraction of noninteracting systems is largest for triples (∼ 0.9), and decreases to ∼ 0.6-0.8 for sextuples. The fraction of strong interactions increases from ∼ 0.1 to ∼ 0.2 from triples to sextuples, and the fraction of dynamically unstable systems increases from ∼ 0.001 to ∼ 0.1-0.2. The larger fractions of strong interactions and dynamical instability in systems with increasing multiplicity can be attributed to increasingly complex secular evolution in these systems. Our results indicate that a significant fraction of high-multiplicity systems interact or become dynamically unstable already during the MS, with an increasing importance as the number of stars increases.

Architecture of Hierarchical Stellar Systems and Their Formation

“…Dynamical interactions in mature hierarchical systems are astrophysically important and can produce some exotic objects [68,69]. However, they are outside the scope of this review.…”

“…Early works where a 'dynamical processing' of binary population in a cluster was studied by assuming some ab initio binaries with universal properties slowly lose their relevance. This said, dynamical evolution of mature hierarchies (after gas dispersal) leads to several astrophysically important outcomes [68,69], while dynamical interactions during or shortly after formation of hierarchies certainly take place and leave their imprints such as misaligned hierarchies or very eccentric orbits.…”

Inner and Outer Orbits in 13 Resolved Hierarchical Stellar Systems

“…Late mergers or collisions can create unusual objects. Hamers (2020) explored outcomes of dynamical evolution using data on real hierarchical systems collected in the Multiple Star Catalog (MSC, Tokovinin 2018a).…”

Architecture of Hierarchical Stellar Systems and their Formation

“…Early works where a 'dynamical processing' of binary population in a cluster was studied by assuming some ab initio binaries with universal properties slowly lose their relevance. This said, dynamical evolution of mature hierarchies (after gas dispersal) leads to several astrophysically important outcomes (Hamers 2020;Toonen et al 2020), while dynamical interactions during or shortly after formation of hierarchies certainly take place and leave their imprints such as misaligned hierarchies or very eccentric orbits.…”

“…Dynamical interactions in mature hierarchical systems are astrophysically important and can produce some exotic objects (Hamers 2020;Toonen et al 2020). However, they are outside the scope of this review.…”