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Paper: The Widest Binary Stars: A Statistical Approach
Volume: 435, Binaries – Key to Comprehension of the Universe
Page: 67
Authors: Longhitano, M.; Binggeli, B.
Abstract: A large and unbiased sample of wide binary stars constitutes an excellent tool for studying the Galaxy. Astronomical applications of wide binaries range from probing the conditions of star formation to testing the dark matter hypothesis. In view of the difficulties in constructing an useful catalogue of wide binaries, we choose a statistical approach to obtain large numbers of binaries, at the expense of individual pair identification. We select a homogeneous sample of nearly one million stars in the direction of the Northern Galactic Pole (NGP) from the sixth data release (DR6) of the Sloan Digital Sky Survey (SDSS). Constructing the angular two-point correlation function (2PCF) reveals a strong clustering signal at angular separations smaller than 10″. Modeling this signal by means of the Wasserman-Weinberg technique allows us to infer the local wide binary number density as well as the power-law index of the semi-major axis distribution in the range from 0.001 pc to 1 pc. The data are consistent with Öpik's law, a single power-law model with index 1, and suggest that about 800 wide pairs with projected physical separations between 0.1 and 0.7 pc exist in our sample, while none are expected to be observed beyond 0.8 pc.
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