J/MNRAS/502/6080 New members of Cygnus OB2 from Gaia DR2 (Orellana+, 2021)
New members of Cygnus OB2 from Gaia DR2.
Orellana R.B., De Biasi M.S., Paiz L.G.
<Mon. Not. R. Astron. Soc. 502, 6080-6093 (2021)>
=2021MNRAS.502.6080O 2021MNRAS.502.6080O (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Positional data ; Parallaxes, trigonometric ;
Proper motions ; Magnitudes
Keywords: astrometry - parallaxes - proper motions -
open clusters and associations : individual : Cygnus OB2
Abstract:
Due to the high quality of Gaia DR2 stellar parallaxes and proper
motions, we can study the Cygnus OB2 region up to G=17.5mag in
circular region centred at (l,b)=(79.8°,+0.8°) of radius
1°. We detect four over-densities in the Vector Point Diagram. We
apply a parametric model of the proper motion distribution and
determine their mean proper motions, identify their members and
estimate their distances by analyzing the parallaxes of the most
probable members. We confirm that one of these regions is Cygnus OB2,
whose mean proper motion is
(pmRA*cosDE,pmDE)=(-2.71±0.02,-4.24±0.02)mas/yr. We identify 2767
astrometric members at an estimated distance of 1683 ± 5 pc. A
detailed comparison of these members with 333 photometric and
spectroscopic Cygnus OB2 members shows that 33 stars of the last group
are not members, 16 of them are O-B stars. 300 members in common lead
to estimate a distance to the association of 1669±6pc. One of the
remaining over-densities is the open cluster UCB585 for which we find
eight more members, located at ∼1460pc. The other two groups count 179
and 188 proper motion members which are distributed throughout the
region and situated at a distance of ∼1280 pc. The estimated distances
of these four groups suggest the existence of different substructures
in the Cygnus OB2 region along the line of sight.
Description:
Gaia DR2 five astrometric parameters and magnitude of the proper
motion members of the association Cygnus OB2 and of the substructures
named 'Right over-density' and 'Left over-density' are presented. For
each group the position, the GaiaDR2 identifier, the parallax and its
error, the proper motion components and their errors and the G
magnitude are given.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 107 2467 New proper motion members of Cygnus OB2
table6.dat 107 179 Right over-density proper motion members
table7.dat 107 188 Left over-density proper motion members
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/ApJS/149/123 : WSRT survey of Cygnus OB2 (Setia Gunawan+, 2003)
J/ApJ/643/238 : Chandra/2MASS sources in Cygnus OB2 (Butt+, 2006)
J/A+A/464/211 : Cyg OB2 Chandra and near-IR obs. (Albacete Colombo+, 2007)
J/A+A/472/557 : Cygnus OB2 region 610MHz sources (Marti+, 2007)
J/ApJS/184/84 : X-ray sources in Cyg OB2 region (Wright+, 2009)
J/A+A/637/A64 : Cygnus OB2 e-MERLIN 21cm survey (COBRaS) (Morford+, 2020)
J/MNRAS/460/2593 : Cygnus OB2 DANCe: Proper motion study (Wright+, 2016)
Byte-by-byte Description of file: table2.dat table6.dat table7.dat
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Bytes Format Units Label Explanations
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1- 15 F15.11 deg RAdeg barycentric right ascension (ICRS)
at Ep=2015.0
17- 31 F15.11 deg DEdeg barycentric declination (ICRS)
at Ep=2015.0
33- 51 A19 --- GaiaDR2 Gaia DR2 identifier
53- 59 F7.4 mas plx Absolute stellar parallax
61- 67 F7.4 mas e_plx Standard error of parallax
69- 75 F7.4 mas/yr pmRA Proper motion in right ascension
(pmRA*cosDE)
77- 83 F7.4 mas/yr e_pmRA Standard error of proper motion
in right ascension
85- 91 F7.4 mas/yr pmDE Proper motion in declination
93- 99 F7.4 mas/yr e_pmDE Standard error of proper motion
in declination
101-107 F7.4 mag Gmag G-band magnitude
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Acknowledgements:
Rosa B. Orellana, rorellan(at)fcaglp.unlp.edu.ar
Leonardo G. Paiz, lpaiz(at)fcaglp.fcaglp.unlp.edu.ar
(End) Rosa B. Orellana [FCAGLP, Argentina], Patricia Vannier [CDS] 22-Mar-2021