http://arxiv.org/abs/1901.03730
Binary and multiple stars have long provided an effective empirical method of testing stellar formation and evolution theories. In particular, the existence of wide binary systems (separations $>$20,000 au) is particularly challenging to binary formation models as their physical separations are beyond the typical size of a collapsing cloud core ($\sim$5,000 – 10,000 au). We mined the recently published Gaia-DR2 catalogue to identify bright co-moving systems in the five-dimensional space (sky position, parallax, and proper motion). We identified 3,741 co-moving binary and multiple stellar candidate systems, out of which 575 have compatible radial velocities for all the members of the system. The candidate systems have separations between $\sim$400 and 500,000 au. We used the analysis tools of the Virtual Observatory to characterize the co-moving system members and to assess their reliability. The comparison with previous co-moving systems catalogues obtained from TGAS showed that these catalogues contain a large number of false systems. In addition, we were not able to confirm the ultra-wide binary population presented in these catalogues. The robustness of our methodology is demonstrated by the identification of well known co-moving star clusters and by the low contamination rate for co-moving binary systems with projected physical separations $<$50,000 au. These last constitute a reliable sample for further studies. The catalogue is available online at the Spanish Virtual Observatory portal.
F. Jiménez-Esteban, E. Solano and C. Rodrigo
Tue, 15 Jan 19
76/83
Comments: Accepted in AJ
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