Potential members of stellar kinematic groups within 30 pc of the Sun.
NAKAJIMA T. and MORINO J.-I.
Abstract (from CDS):
We analyze the kinematic histories of stars within 30 pc of the Sun, for which three-dimensional spatial coordinates and three-dimensional velocity vectors are available. From this sample, we extract members of stellar kinematic groups (SKGs) in the following manner. First, we consider in the three-dimensional velocity space centered on the local standard of rest, a sphere with a radius of 8 km/s centered on the mean velocity vector of a particular SKG. Around each SKG velocity center, we have found a significant excess of stars compared to background field stars. For each candidate, in the three-dimensional spatial coordinate space, its trajectory is traced back in time by the age of the relevant SKG to obtain the estimated distance from the SKG center at the time of the SKG's birth by the epicyclic approximation and harmonic vertical motion. It often happens that a star is a candidate member of multiple SKGs. Then we rank the candidacy to multiple SKGs based on the smallness of distance separations. In this manner, we have kinematically selected 238 candidates. We further impose at least one of the following qualitative criteria for being a member: spectral type A or B, variability, or EUV and X-ray emission. We have finally selected 137 candidate members of SKGs out of a sample of 966 stars.
stars: kinematics and dynamics - solar neighborhood