SIMBAD references

2015A&A...575A..35B - Astronomy and Astrophysics, volume 575A, 35-35 (2015/3-1)

Close encounters of the stellar kind.


Abstract (from CDS):

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 re-reduction of the Hipparcos data complemented by the original Hipparcos and Tycho-2 catalogues, along with recent radial velocity surveys, I integrate the orbits of over 50000 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 0.5pc respectively, although some of these stars have questionable data. Of the 14 stars coming within 1pc, 5 were found by at least one of three previous studies (which found a total of 7 coming within 1pc). The closest encounter appears to be Hip 85605, a K or M star, which has a 90% probability of coming between 0.04 and 0.20pc between 240 and 470kyr from now (90% Bayesian confidence interval). However, its astrometry may be incorrect, in which case the closest encounter found is the K7 dwarf GL 710, which has a 90% probability of coming within 0.10-0.44pc in about 1.3Myr. A larger perturbation may have been caused by gamma Microscopii, a G6 giant with a mass of about 2.5M, which came within 0.35-1.34pc (90% confidence interval) around 3.8Myr ago.

Abstract Copyright:

Journal keyword(s): comets: general - methods: numerical - stars: kinematics and dynamics - stars: general - methods: statistical - Cloud Oort

VizieR on-line data: <Available at CDS (J/A+A/575/A35): table3.dat>

Simbad objects: 717

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