Аннотация
Although rare in the Milky Way, star-star collisions are predicted to occur
within the dense cores of globular clusters, in evolving triple star systems,
and possibly very near the Galactic center. It has recently been shown that
very wide binary star systems (binary stars separated by at least 1000 AU,
where 1 AU is the Earth-Sun distance) can have their stellar orbits driven to
very eccentric states by other passing field stars and the Galactic tide,
forcing close passages between companion stars. Here we report numerical
simulations demonstrating that this process is a major but unrealized source of
stellar collisions. Occasionally, the eccentricities of very wide binaries
become so extreme that their periastron (distance of closest approach, or q)
falls below the combined radii of the companion stars, and they collide during
periastron passage. Tidal interactions between the companion stars prevent some
collisions by shrinking the binary orbit thereby making it less susceptible to
galactic perturbations. Nonetheless, this mechanism produces a stellar
collision every ~2500 years in the Galaxy, making very wide binaries the
dominant source of collisions in the Milky Way. These collisions should yield a
small population of single, Li-depleted, rapidly rotating massive stars.
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