Name/Affiliation: Kevin Gullikson (University of Texas)
A Search for Disk-Born Stellar Companions
Most stars form in binary or multiple systems through either the core fragmentation or circumstellar disk fragmentation mechanisms. While simulations of these processes can not yet follow the systems to a steady state, disk fragmentation tends to generate companions with a lower mass than core fragmentation. Disks around young intermediate-mass stars are massive enough to create low-mass stellar companions, like a scaled-up version of disk-instability planet formation. We will describe a survey of nearby main sequence A and B-type stars in which we specifically look for K/M companions within $\sim 100$ AU. We use high signal-to-noise ratio, high resolution echelle spectra to search directly for the spectral lines of the secondary. This method can detect lower-mass companions than current adaptive optics imaging or radial velocity monitoring for companions from 20-50 AU for most stars in our sample, where we expect a population of disk-born companions may reside. In addition, the high signal-to-noise ratio measurements allow us to constrain the temperature of known single-lined spectroscopic binary companions. We will discuss early results of our survey, which is nearly complete for B stars.