The Formation, Evolution, and Fate of Multiple Star Systems

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

Stars are born within clouds of dense gas that collapse under their own gravity. Sometimes solitary stars form, like our own Sun. But, stars also commonly form in binary or multiple star systems that are bound by gravity. It remains unknown how most of these binary stars form. One way that they may form is within the disk of gas and dust that forms around the newborn star. They may also first form separately and later become bound due to their own mutual gravity. The number of forming binary systems, their separations, and the environment that the binary stars formed within must be examined to understand why they are so common. The investigators seek to understand formation of binary stars, by finding and examining previously unknown newborn binary stars. These newborn stars will be observed with the NSF's Very Large Array (VLA) and the Atacama Large Millimeter/submillimeter Array (ALMA) radio telescopes. These high-resolution observations will discover binary stars forming with separations smaller than the size of our own Solar System. They will show where binary stars form, how they most likely formed, and if they will remain in a binary system throughout their lives. This project will help reveal how often Solar Systems like our own form around a single star. As part of this project, radio astronomy will be integrated into undergraduate and graduate education at the University of Oklahoma. Lab activities using the local 3-meter radio telescope will be designed to fulfill educational goals at multiple levels. Collaboration with local high schools will also enable them to conduct radio astronomy observations from their classroom. The investigators will conduct a systematic search for multiple stars. The investigators will analyze surveys of the Orion and Perseus star forming regions, sampling over 400 proto-stars in total, achieving better than 30 Astronomical Unit resolution. The companion separation distributions between Orion and Perseus will be compared between themselves and with the distributions measured for field stars using statistical tests. For a subset of the systems, molecular line imaging from ALMA will be used to verify that the disks are Keplerian and to measure the masses of the proto-stars and estimate their mass ratios. Finally, even if systems lack a companion, but have a clear disk, their likelihood of later fragmentation will be assessed. In addition to this census, their formation conditions will be characterized and the potential for companion formation will be estimated. The investigators will create a clearer picture of multiplicity at the time of early star formation and how the distribution of multiple stars must change as the stellar systems mature to the main sequence. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.