1. The Relationships of Binary Stars

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    The widest binaries and triple systems have very elongated orbits, so the stars spend most of their time far apart. But once in every orbital revolution they are at their closest approach, as depicted in this artist’s impression by Karen Teramura (UH Institute for Astronomy) with background photograph by Wei-Hao Wang.

    New NAI-supported research published the journal Nature is helping astrobiologists understand the formation of binary stars that orbit each other at distances of up to a light-year. The formation of these 'very wide binaries’ has been a mystery because the stars can be further apart than the size of the collapsing clouds from which they form. Using computer simulations, the research team led by Bo Reipurth of the University of Hawaii and Seppo Mikkola of the University of Turku in Finland, has uncovered a mechanism for how wide binaries are created.

    When two stars form in the tight confines of a cloud core, their gravitational pull on one another becomes a 'chaotic dance.’ Ultimately, the lighter of the two young stars is tossed to the outer edge of the cloud core for long periods of time before falling back toward the center. Eventually, as the stars inside the cloud core grow larger and larger, the smaller star can be thrown into a wide orbit, or even ejected from the system entirely. Studying the formation of such systems is important for astrobiologists who are trying to determine the diversity of stellar environments that exist beyond our solar system and the potential for habitable worlds around stars other than our sun.

    Source: [University of Hawaii]