Close encounters of the stellar kind
Abstract
Stars which pass close to the Sun can perturb the Oort cloud, injecting comets into the inner solar system where they may collide with the Earth. Using van Leeuwen's rereduction of the Hipparcos data complemented by the original Hipparcos and Tycho2 catalogues, along with recent radial velocity surveys, I integrate the orbits of over 50 000 stars through the Galaxy to look for close encounters. The search uses a Monte Carlo sampling of the covariance of the data in order to properly characterize the uncertainties in the times, distances, and speeds of the encounters. I show that modelling stellar encounters by assuming instead a linear relative motion produces, for many encounters, inaccurate and biased results. I find 42, 14, and 4 stars which have encounter distances below 2, 1, and 0.5 pc respectively, although some of these stars have questionable data. Of the 14 stars coming within 1 pc, 5 were found by at least one of three previous studies (which found a total of 7 coming within 1 pc). The closest encounter appears to be
Full Table 3 is only available at the CDS via anonymous ftp to http://cdsarc.ustrasbg.fr (ftp://130.79.128.5) or via http://cdsarc.ustrasbg.fr/vizbin/qcat?J/A+A/575/A35
 Publication:

Astronomy and Astrophysics
 Pub Date:
 March 2015
 DOI:
 10.1051/00046361/201425221
 arXiv:
 arXiv:1412.3648
 Bibcode:
 2015A&A...575A..35B
 Keywords:

 comets: general;
 methods: numerical;
 stars: kinematics and dynamics;
 stars: general;
 methods: statistical;
 Oort Cloud;
 Astrophysics  Solar and Stellar Astrophysics;
 Astrophysics  Earth and Planetary Astrophysics
 EPrint:
 Accepted to A&