I. Ramírez¹, A. T. Bajkova², V. V. Bobylev^2,3, I. U. Roederer⁴, D. L. Lambert¹, M. Endl¹, W. D. Cochran¹, P. J. MacQueen¹ and R. A. Wittenmyer^5,6

¹McDonald Observatory and Department of Astronomy, University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, Texas 78712-1205, USA
²Central (Pulkovo) Astronomical Observatory of RAS, 65/1, Pulkovskoye Chaussee, St. Petersburg 196140, Russia
³Sobolev Astronomical Institute, St. Petersburg State University, Bibliotechnaya pl. 2, St. Petersburg 198504, Russia
⁴Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109, USA
⁵School of Physics, UNSW Australia, Sydney 2052, Australia
⁶Australian Centre for Astrobiology, University of New South Wales, UNSW Kensington Campus, Sydney 2052, Australia

Dynamical information along with survey data on metallicity and in some cases age have been used recently by some authors to search for candidates of stars that were born in the cluster where the Sun formed. We have acquired high-resolution, high signal-to-noise ratio spectra for 30 of these objects to determine, using detailed elemental abundance analysis, if they could be true solar siblings. Only two of the candidates are found to have solar chemical composition. Updated modeling of the stars’ past orbits in a realistic Galactic potential reveals that one of them, HD 162826, satisfies both chemical and dynamical conditions for being a sibling of the Sun. Measurements of rare-element abundances for this star further confirm its solar composition, with the only possible exception of Sm. Analysis of long-term high-precision radial velocity data rules out the presence of hot Jupiters and confirms that this star is not in a binary system. We find that chemical tagging does not necessarily benefit from studying as many elements as possible but instead from identifying and carefully measuring the abundances of those elements that show large star-to-star scatter at a given metallicity. Future searches employing data products from ongoing massive astrometric and spectroscopic surveys can be optimized by acknowledging this fact.

Reference
Ramírez I, Bajkova AT, Bobylev VV, Roederer IU, Lambert DL, Endl M, Cochran WD, MacQueen PJ and Wittenmyer RA (2014) Elemental Abundances of Solar Sibling Candidates. The Astrophysical Journal 787:154.
[doi:10.1088/0004-637X/787/2/154]

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