Orbital Parameters and Binary Properties of 37 FGK stars in the Cores of
  Open Clusters NGC 2516 and NGC 2422
  We present orbits for 24 binaries in the field of open cluster NGC 2516 (~150
Myr) and 13 binaries in the field of open cluster NGC 2422 (~130 Myr) using
results from a multi-year radial velocity survey of the cluster cores. Six of
these systems are double-lined spectroscopic binaries (SB2s). We fit these RV
variable systems with orvara, a MCMC-based fitting program that models
Keplerian orbits. We use precise stellar parallaxes and proper motions from
Gaia EDR3 to determine cluster membership. We impose a barycentric radial
velocity prior on all cluster members; this significantly improves our orbital
constraints. Two of our systems have periods between 5 and 15 days, the
critical window in which tides efficiently damp orbital eccentricity. These
binaries should be included in future analyses of circularization across
similarly-aged clusters. We also find a relatively flat distribution of binary
mass ratios, consistent with previous work. With the inclusion of TESS
lightcurves for all available targets, we identity target 378-036252 as a new
eclipsing binary. We also identify a field star whose secondary has a mass in
the brown dwarf range, as well as two cluster members whose RVs suggest the
presence of an additional companion. Our orbital fits will help constrain the
binary fraction and binary properties across stellar age and across stellar
environment.
