Measuring the Unresolved Binary Fraction in the Core of the Orion Nebula Cluster

One of the great mysteries in modern astronomy is the process by which stars form. Stars can be much larger or smaller than the Sun, yet somehow all originate from the same clouds of gas and dust. In many cases, these forming stars will come in twin pairs called binary stars.

It is uncertain how binary stars form, whether they are more likely to be close to each other or far apart, and if they are more likely to be "fraternal or identical". In this study, the researchers will search for new binary stars in the nearby Orion stellar nursery. They will look for binary stars that are closer to each other than Saturn is to the Sun.

These close binary stars have been difficult to find in the past, and the researchers will use new techniques to discover them. The investigator seeks to motivate a wider group of students to pursue science research by creating a workshop on data science, based on their research efforts. The investigator would recruit students from underserved communities.

The Orion Nebula Cluster (ONC) is an ideal laboratory for this work, as it is the nearest site of massive star formation. Previous binary star surveys of the cluster have only been sensitive to separations > 10 Astronomical Units. These surveys have found a significant decrease in multiple systems at the widest separations, in contrast to stars in the field.

Using the W.M. Keck observatory, the research group will target sources in the inner ONC with high resolution, near-infrared spectroscopy coupled with adaptive optics. This work will be enhanced by the use of a laser frequency comb for precision wavelength calibration, improving radial velocity uncertainties by a factor of 10.

The group will determine the fraction of very close binaries (separation < 10 AU) for the first time in the central ONC, and compare the results to both measurements in other clusters and N-body simulations. Ultimately, this research will determine whether binary star properties are universal and which processes are dominant in shaping those properties.

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.