Abstract
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 parametrized 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. 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.
Original language | English |
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Pages (from-to) | 1838–1842 |
Number of pages | 5 |
Journal | Monthly Notices of the Royal Astronomical Society (MNRAS) |
Volume | 484 |
Issue number | 2 |
Early online date | 16 Jan 2019 |
DOIs | |
Publication status | Published - 1 Apr 2019 |
Keywords
- astro-ph.SR
- astro-ph.GA
- Stars: distances
- Associations: individual: Cygnus OB2
- Stars: early-type
- Stars: massive
- Open clusters
- Parallaxes
- Astrometry