The origin of binary stars

August 21, 2017, Harvard-Smithsonian Center for Astrophysics
The origin of binary stars
An image taken at submillimeter wavelengths of a star-forming core, showing that it contains two young stellar embryos. Astronomers have concluded from a systematic study of very young cores that most embryonic stars form in multiple systems, and later some of them separate. Credit: Sadavoy and Stahler

The origin of binary stars has long been one of the central problems of astronomy. One of the main questions is how stellar mass affects the tendency to be multiple. There have been numerous studies of young stars in molecular clouds to look for variations in binary frequency with stellar mass, but so many other effects can influence the result that the results have been inconclusive. These complicating factors include dynamical interactions between stars that can eject one member of a multiple system, or on the other hand might capture a passing star under the right circumstances. Some studies, for example, found that younger stars are more likely to be found in binary pairs. One issue with much of the previous observational work, however, has been the small sample sizes.

CfA astronomer Sarah Sadavoy and her colleague used combined observations from a large radio wavelength survey of young stars in the Perseus cloud with submillimeter observations of the natal dense core material around these stars to identify twenty-four multiple systems. The scientists then used a submillimeter study to identify and characterize the dust cores in which the stars are buried. They found that most of the embedded binaries are located near the centers of their dust cores, indicative of their still being young enough to have not drifted away. About half of the binaries are in elongated core structures, and they conclude that the initial cores were also elongated structures. After modeling their findings, they argue that the most likely scenarios are the ones predicting that all stars, both single and binaries, form in widely separated binary pair systems, but that most of these break apart either due to ejection or to the core itself breaking apart. A few systems become more tightly bound. Although other studies have suggested this idea as well, this is the first study to do so based on observations of very young, still embedded stars. One of their most significant major conclusions is that each dusty core of material is likely to be the birthplace of two stars, not the single star usually modeled. This means that there are probably twice as many stars being formed per than is generally believed.

Explore further: New evidence that all stars are born in pairs

More information: Sarah I. Sadavoy et al. Embedded binaries and their dense cores, Monthly Notices of the Royal Astronomical Society (2017). DOI: 10.1093/mnras/stx1061

Related Stories

Massive multiple star system found by astronomers

August 7, 2017

A group of astronomers led by Javier Lorenzo of the University of Alicante, Spain, has discovered that the binary star system HD 64315 is more complex than previously thought. The new study reveals that HD 64315 contains ...

No close partner for young, massive stars in Omega Nebula

February 14, 2017

Astronomers from Leuven (Belgium) and Amsterdam (Netherlands) have discovered that massive stars in the star-forming region M17 (the Omega Nebula) are—against expectations—not part of a close binary. They have started ...

Most stars are born in clusters, some leave 'home'

September 24, 2014

New modeling studies from Carnegie's Alan Boss demonstrate that most of the stars we see were formed when unstable clusters of newly formed protostars broke up. These protostars are born out of rotating clouds of dust and ...

How single stars lost their companions

September 15, 2011

(PhysOrg.com) -- Not all stars are loners. In our home galaxy, the Milky Way, about half of all stars have a companion and travel through space in a binary system. But explaining why some stars are in double or even triple ...

Recommended for you

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

f_darwin
not rated yet Aug 22, 2017
Based on our information Binary and multi stars are quiet common. soon (cosmological time) Jupiter will make solar system a binary. currently Jupiter evolution is on verge of being a proto- star. MG1

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.