University of Hertfordshire

From the same journal

From the same journal

Disentangling the spatial substructure of Cygnus OB2 from Gaia DR2

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  • JD

    Accepted author manuscript, 798 KB, PDF document


  • S. R. Berlanas
  • N. Wright
  • A. Herrero
  • J. E. Drew
  • D. J. Lennon
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Original languageEnglish
Pages (from-to)1838–1842
Number of pages5
JournalMonthly Notices of the Royal Astronomical Society
Early online date16 Jan 2019
Publication statusPublished - 1 Apr 2019


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.


© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society


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