Searching for Faint Comoving Companions To The α Centauri System In The VVV Survey Infrared Images


Field of view analyzed in this study, each rectangle corresponds to one VVV tile. The position of the α Cen AB system is marked in yellow-orange (separation not to scale) stars and Proxima as a red star. The grey ellipse shows an approximate orbit of Proxima around the AB pair, from Kervella et al. (2017). The green arrow shows the proper motion of the system. The total area covered by this search is ~19 sq. degrees. The limiting distance of 7000 AU (and 1200 to Proxima) is given by the distance to the South-East limit of the tile 'd015' (and 'd014' for Prox- ima). To the North-East and North-West the limiting separation almost reach 20.000 AU from α Cen AB.

The VVV survey has observed the southern disk of the Milky Way in the near infrared, covering 240 deg2 in the ZYJHKS filters.

We search the VVV Survey images in a ∼19 deg2 field around α Centauri, the nearest stellar system to the Sun, to look for possible overlooked companions that the baseline in time of VVV would be able to uncover. The photometric depth of our search reaches Y∼19.3 mag, J∼19 mag, and KS∼17 mag. This search has yielded no new companions in α Centauri system, setting an upper mass limit for any unseen companion well into the brown dwarf/planetary mass regime. The apparent magnitude limits were turned into effective temperature limits, and the presence of companion objects with effective temperatures warmer than 325K can be ruled out using different state-of-the-art atmospheric models.

These limits were transformed into mass limits using evolutionary models, companions with masses above 11 MJup were discarded, extending the constraints recently provided in the literature up to projected distances of d<7 000 AU from α Cen AB and ∼1200 AU from Proxima. In the next few years, the VVV extended survey (VVVX) will allow to extend the search and place similar limits on brown dwarfs/planetary companions to α Cen AB for separations up to 20 000AU.

J. C. Beamin, D. Minniti, J. B. Pullen, V. D. Ivanov, E. Bendek, A.Bayo, M. Gromadzki, R. Kurtev, P. W. Lucas, R. P. Butler
(Submitted on 17 Aug 2017)

Comments: 8 pages, 6 figures, 3 tables. Accepted for publication in MNRAS
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
DOI: 10.1093/mnras/stx2144
Cite as: arXiv:1708.05365 [astro-ph.SR] (or arXiv:1708.05365v1 [astro-ph.SR] for this version)
Submission history
From: Juan Carlos Beamín
[v1] Thu, 17 Aug 2017 17:08:43 GMT (4222kb,D)
https://arxiv.org/abs/1708.05365

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