When: January 24, 2018 @12:00-1:00pm
Where: B305 (PAB)
Very wide binaries and comoving stars in the Gaia era
Conatal and coeval stars are important tracers of kinematics, stellar models,
dark matter physics, and star and planet formation processes in the Galaxy:
The disruption of these systems is sensitive to the Galactic gravitational
field, their spectra can be used to calibrate stellar models at fixed age and
chemical abundances, and changes or differences in their surface abundances
likely relates to the stability and mass in planetary systems.
A strong indicator that a given pair of stars are coeval is that they are
comoving in three dimensions.
I’ll discuss our group’s effort to identify large samples of comoving stars
(widely-separated or recently dissociated stellar multiplets) using astrometric
data from the Gaia mission, combined with spectroscopic followup.
With astrometry from the (mostly local) Gaia data release 1, we have already
found some surprises: confidently coeval stars separated by >1 pc, and a wide
binary with abundance differences that match rocky abundance patterns.
In anticipation of at least an order of magnitude increase in the number of
comoving stars in Gaia data release 2, I’ll also discuss prospects for (1) using
their kinematics to study the gravitational field of the Milky Way, and (2)
using their chemical abundances to study star formation and the outcomes of
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