Detalles de publicación

PP 019004

Disentangling the spatial substructure of Cygnus OB2 from Gaia DR2

S. R. Berlanas (1,2), N. Wright (3), A. Herrero (1,2), J. E. Drew (4) and D. J. Lennon (1,5)
(1) Instituto de Astrofisica de Canarias (2) Departamento de Astrofisica, ULL (3) Keele University (4) University of Hertfordshire (5) ESA, European Space Astronomy Centre.
For the first time, we have explored the spatial substructure of the Cygnus OB2 association using parallaxes from the recent second Gaia data release. We find significant line-of-sight substructure within the association, which we quantify using a parameterised model that reproduces the observed parallax distribution. This inference approach is necessary due to the non-linearity of the parallax-distance transformation and the asymmetry of the resulting probability distribution. By using a Markov Chain Monte Carlo ensemble sampler and an unbinned maximum likelihood test we identify two different stellar groups superposed on the association. We find the main Cygnus OB2 group at ∼1760 pc, further away than recent estimates have envisaged, and a foreground group at ∼1350 pc. We also calculate individual membership probabilities and identify outliers as possible non-members of the association.

 
Aceptado para publicación en MNRAS | Enviado el 2019-01-11 | Proyecto P/309808