Volume 594, October 2016
|Number of page(s)||15|
|Section||Celestial mechanics and astrometry|
|Published online||19 October 2016|
Close stellar conjunctions of α Centauri A and B until 2050
An mK = 7.8 star may enter the Einstein ring of α Cen A in 2028⋆
1 Unidad Mixta Internacional Franco-Chilena de Astronomía (CNRS UMI 3386), Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile
2 LESIA (UMR 8109), Observatoire de Paris, PSL Research University, CNRS, UPMC, Univ. Paris-Diderot, 5 Place Jules Janssen, 92195 Meudon, France
3 Laboratoire Lagrange, Université Nice Sophia-Antipolis, Observatoire de la Côte d’Azur, CNRS, CS 34229, 06304 Nice Cedex, France
4 European Southern Observatory, Alonso de Córdova 3107, Casilla 19001, Santiago 19, Chile
Received: 28 June 2016
Accepted: 9 September 2016
The rapid proper motion of the α Cen pair (≈3.7 arcsec yr-1) and its location close to the galactic plane on a rich stellar background combine constructively to make them excellent candidates for close stellar conjunctions with more distant stars. Adding new differential astrometry to archival data, we have refined the orbital parameters, barycentric proper motion and parallax of α Cen and compute its apparent trajectory on sky over the coming decades. Based on NTT/SUSI2, NTT/SOFI, and VLT/NACO maps of the field stars around the trajectories of α Cen A and B, we present a catalog of the expected close conjunctions until 2050. An exceptional event will take place in early May 2028, when α Cen A will come within ρmin = 0.015 ± 0.135 arcsec of the mK = 7.8 star 2MASS 14392160-6049528 (hereafter S5). In terms of impact parameter and contrast, this is the most favorable stellar conjunction of α Cen within at least the next three decades. With an angular diameter of θLD = 0.47 ± 0.05 mas, it is likely that S5 is a red giant or supergiant located at several kiloparsecs. The approached stars will act as moving light probes in transmission through the environment of α Cen. The observation of these close conjunctions holds great promises to search for planets and other low mass objects in the α Cen system using photometry and astrometry. The relativistic displacement of the approached star images will be observable, with significant deflection angles in the milliarcsecond range. The small impact parameter of the conjunction with S5 means that this star has a probability of 45% of entering the Einstein ring of α Cen A. The gravitational amplification of the flux of S5 could reach a factor five for the combination of the two lensed images. The proper motion, orbital parameters and parallax of α Cen will be measurable with an extreme accuracy from differential astrometry with the S stars. This will be valuable, for example to prepare the recently announced Breakthrough Starshot initiative to send interstellar nanocrafts to α Centauri.
Key words: astrometry / proper motions / stars: individual: αCen / stars: solar-type / binaries: general / ephemerides
© ESO, 2016
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.