Orbits and Disks of the Young Double-Lined Spectroscopic Binaries StHα 34 and V562 Ori

StHα 34 (HBC 425) and V562 Ori (JW 707) are short-period, pre-main sequence spectroscopic binaries in the Taurus and Orion star-forming regions, respectively. Both systems host circumbinary disks; in StHα 34, active accretion is occurring onto one or both stars. These relatively rare double-lined, disk-bearing systems provide the opportunity to study disk structure and evolution and the accretion process in complex environments, yielding clues to the dynamics of accretion onto massive planets and to disk dissipation. We obtained echelle spectra in visible light using the McDonald Observatory Harlan J. Smith 2.7 meter telescope with the Tull spectrograph and in the near-infrared using the Lowell Discovery Telescope with the IGRINS spectrograph. With these data we measure stellar radial velocities using a spectral-line broadening function analysis and cross-correlation, and solve for the binary orbital parameters. Time-series spectra used to characterize the orbit of StHα 34 (P=21 days, mass ratio ~1, mid-M spectral types, e=0.6) reveal a complex Hα emission line profile; the system's K2 light curve shows "dipper" behavior. We explore correlations between the orbital and gas dynamics in this young binary and find that its variability is more stochastic than the predictable periastron accretion bursts seen in the binary-accretion archetype, DQ Tau. These differences, possibly the result of the higher accretion rate in StHα 34, allow us to probe the binary-disk interaction in a new regime. For V562 Ori (P=12 days, mass ratio ~1, mid-K spectral types, e=0.1), a lack of near-infrared excess in the system indicates no warm dust in close proximity to the stars and no apparent accretion; however, 3.6 and 4.5 micron data from the YSOVARS program demonstrate the presence of cool circumbinary dust. Variability in the brightness and color of the mid-infrared excess appears to correlate with the orbital period. This research was supported in part by NSF awards AST-1313399 and AST-1518081.