Eccentricity distribution of wide low-mass binaries
  Distribution of eccentricities of very wide (up to 10 kau) low-mass binaries
in the solar neighborhood is studied using the catalog of El-Badry and Rix
(2018) based on Gaia. Direction and speed of relative motions in wide pairs
contain statistical information on the eccentricity distribution, otherwise
inaccessible owing to very long orbital periods. It is found that the
eccentricity distribution is close to the linear (thermal) one f(e) = 2e$
However, pairs with projected separations <200 au have less eccentric orbits,
while f(e) for very wide pairs appears to be slightly super-thermal, with an
excess of very eccentric orbits. Eccentricity of any wide binary can be
constrained statistically using direction and speed of its motion. Thermal
eccentricity distribution signals an important role of stellar dynamics in the
formation of wide binaries, although disk-assisted capture also can produce
such pairs with eccentric orbits.
