Searching for Faint Comoving Companions to the $\alpha$ Centauri system in the VVV Survey Infrared Images

Abstract

The VVV survey has observed the southern disk of the Milky Way in the near infrared, covering 240 deg${}^2$ in the $ZYJH{K}_S$ filters. We search the VVV Survey images in a $\sim$19 deg${}^2$ field around $\alpha$ 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\sim$19.3 mag, $J\sim$19 mag, and $K_S\sim$17 mag. This search has yielded no new companions in $\alpha$ 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 M${}_{Jup}$ were discarded, extending the constraints recently provided in the literature up to projected distances of d<7 000 AU from $\alpha$ Cen AB and $\sim$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 $\alpha$ Cen AB for separations up to 20 000AU.

8 pages, 6 figures, 3 tables. Accepted for publication in MNRAS

References in corpus (14)

• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• Proxima's orbit around Alpha Centauri
• Water Clouds in Y Dwarfs and Exoplanets
• Close stellar conjunctions of alpha Centauri A and B until 2050 - An mK = 7.8 star may enter the Einstein ring of alpha Cen A in 2028
• The Solar Neighborhood. XXXIV. A Search for Planets Orbiting Nearby M Dwarfs using Astrometry
• Hubble Space Telescope search for the transit of the Earth-mass exoplanet Alpha Centauri Bb
• Toward detection of terrestrial planets in the habitable zone of our closest neighbor: Proxima Centauri
• Temperature constraints on the coldest brown dwarf known WISE 0855-0714
• Upper limits for Mass and Radius of objects around Proxima Cen from SPHERE/VLT
• Milky Way demographics with the VVV Survey III. Evidence for a Great Dark Lane in the 157 Million Star Bulge Color-Magnitude Diagram
• Properties of the solar neighbor WISE J072003.20-084651.2
• Near-IR trigonometric parallaxes of nearby stars in the Galactic plane using the VVV