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TOPIC: Very Wide Binaries

Blobrana

L

Posts: 131433

Date: May 7 17:41 2012

2M0525-7425AB and 2M1348-1344AB	Permalink

Title: Discovery of Two Very Wide Binaries with Ultracool Companions and a New Brown Dwarf at the L/T Transition Authors: Koraljka Muzic, Jacqueline Radigan, Ray Jayawardhana, Valentin D. Ivanov, Jacqueline K. Faherty, Radostin G. Kurtev, Alejandro Nunez, Henri M. J. Boffin, Olivier Hainaut, Kelle Cruz, David Jones, Stanimir Metchev, Amy Tyndall, Jura Borissova We present the discovery and spectroscopic follow-up of a nearby late-type L dwarf (2M0614+3950), and two extremely wide very-low-mass binary systems (2M0525-7425AB and 2M1348-1344AB), resulting from our search for common proper motion pairs containing ultracool components in the Two Micron All Sky Survey (2MASS) and the Wide-field Infrared Survey Explorer (WISE) catalogues. The near-infrared spectrum of 2M0614+3950 indicates a spectral type L9 ±1 object residing at a distance of 26.1 ±1.3 pc. The optical spectrum of the 2M0525-7425 primary reveals an M3.0 ±0.5 dwarf, accompanied by a secondary previously classified as L2. The system has an angular separation of ~44", equivalent to ~2000 AU at the 45.7 ±2.5 pc distance. Using optical and infrared spectra, respectively, we classify the components of 2M1348-1344AB as M4.5 ±0.5 and T6 ±1. The angular separation of ~68" is equivalent to ~1300 AU at the distance of 19.2 ±0.9 pc. 2M1348-1344AB is one of only five very wide (separation > 1000 AU) systems containing late T dwarfs known to date. Read more (1380kb, PDF) __________________

Blobrana

L

Posts: 131433

Date: Jul 5 01:53 2010

Very Wide Binaries	Permalink

Title: Very Wide Binaries and Other Comoving Stellar Companions: A Bayesian Analysis of the Hipparcos Catalogue Authors: Ed Shaya, Rob Olling 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 behaviour 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, beta02 and beta03 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. Read more (191kb, PDF) __________________

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