[1007.0425] Very Wide Binaries and Other Comoving Stellar Companions: A Bayesian Analysis of the Hipparcos Catalogue

Authors: Ed Shaya, Rob Olling

Date: 2 Jul 2010

Abstract: We develop Bayesian statistical methods for discovering and assigning probabilities to non-random (e.g., physical) stellar proper motion companions. They are either presently bound or from previously bound systems. The probabilities depend on similarities in proper motion parallel and perpendicular to the brighter component's motion, parallax, and the local phase-space density of field stars. Control experiments are conducted to understand the behavior of false positives. The technique is applied to the Hipparcos Catalogue within 100 pc. This is the first all-sky survey to locate escaped companions still drifting along with each other out to several parsecs. In both the 25 - 50 and the 50 - 100 pc distance ranges, about 50 high probability companions with separations between 0.01 - 1 pc are found. Evidence is found for a population of several 100 companions separated by 1 - 10 pc. We find these unnoticed naked-eye companions (both with V<6): {\delta} Vel and HIP43797, Alioth ({\epsilon} UMa) and Megrez ({\delta} UMa), {\gamma} and {\tau} Cen, {\phi} Eri and {\eta} Hor, 62 and 63 Cnc, {\gamma} and {\tau} Per, {\zeta} and {\delta} Hya, {\beta}02 and {\beta}03 Tuc, N Vel and HIP47479, {\iota} and 97 Tau, HIP98174 and HIP97646, {\nu} and 46 Tau, and 81 and 84 UMa. High probability fainter companions (V>6) of primaries with V<4 are found: Fomalhaut ({\alpha} PsA), Mizar, {\alpha} Lib, {\gamma} UMa, {\iota} Peg, {\alpha} Lib, {\delta} Boo, Alvahet ({\iota} Cephi), Chow ({\beta} Ser), {\delta} Ara, and {\kappa} Phe.

abs pdf

Jul 05, 2010

1007.0425 (/preprints)
2010-07-05, 09:13 [edit]

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