J/MNRAS/508/2370 Revisiting the Cygnus OB associations (Quintana+, 2021)
Revisiting the Cygnus OB associations.
Quintana A.L., Wright N.J.
<Mon. Not. R. Astron. Soc. 508, 2370-2385 (2021)>
=2021MNRAS.508.2370Q 2021MNRAS.508.2370Q (SIMBAD/NED BibCode)
ADC_Keywords: Parallaxes, trigonometric ; Positional data ; Proper motions ;
Stars, ages ; Stars, distances ; Stars, OB ; Stellar distribution
Keywords: stars: kinematics and dynamics - stars: early-type - stars: massive -
stars: distances - open clusters and associations: individual:
Cyg OB1, Cyg OB2, Cyg OB3, Cyg OB8, Cyg OB9
Abstract:
OB associations play an important role in Galactic evolution, though
their origins and dynamics remain poorly studied, with only a small
number of systems analysed in detail. In this paper we revisit the
existence and membership of the Cygnus OB associations. We find that
of the historical OB associations only Cyg OB2 and OB3 stand out as
real groups. We search for new OB stars using a combination of
photometry, astrometry, evolutionary models and an SED fitting
process, identifying 4680 probable OB stars with a reliability of
>90%. From this sample we search for OB associations using a new and
flexible clustering technique, identifying 6 new OB associations. Two
of these are similar to the associations Cyg OB2 and OB3, though the
others bear no relationship to any existing systems. We characterize
the properties of the new associations, including their velocity
dispersions and total stellar masses, all of which are consistent with
typical values for OB associations. We search for evidence of
expansion and find that all are expanding, albeit anistropically, with
stronger and more significant expansion in the direction of Galactic
longitude. We also identify two large-scale (160pc and 25km/s)
kinematic expansion patterns across the Cygnus region, each including
three of our new associations, and attribute this to the effects of
feedback from a previous generation of stars. This work highlights the
need to revisit the existence and membership of the historical OB
associations, if they are to be used to study their properties and
dynamics.
Description:
Position, astrometry and SED-fitted parameters of the 4680 identified
probable OB stars. Group membership (from A to F) has also been
indicated whenever relevant.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
cyg.dat 211 4680 Positional, astrometric and SED-fitted
parameters for the 4680 probable OB stars
(corrected version, 24-Jan-2022)
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See also:
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
Byte-by-byte Description of file: cyg.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- --- [Gaia EDR3]
11- 29 I19 --- GaiaEDR3 Gaia EDR3 source identification number
31- 40 F10.6 deg RAdeg Barycentric right ascension of the source
(ICRS) at Ep=2016.0 (ra)
42- 50 F9.6 deg DEdeg Barycentric right ascension of the source
(ICRS) at Ep=2016.0 (dec)
52- 57 F6.3 mas Plx Absolute stellar parallax of the source at
the Ep=2016.0
59- 63 F5.3 mas e_Plx Standard error of the stellar parallax
at Ep=2016.0
65- 71 F7.3 mas/yr pmRA Proper motion in right ascension pmRA*cosDE
of the source in ICRS at Ep=2016.0
73- 77 F5.3 mas/yr e_pmRA Standard error of proper motion in
right ascension direction
79- 85 F7.3 mas/yr pmDE Proper motion in declination direction of the
source in ICRS at Ep=2016.0
87- 91 F5.3 mas/yr e_pmDE Standard error of proper motion in
declination direction
93- 99 F7.3 mas/yr pml Proper motion in Galactic longitude
direction at Ep=2016.0
101-105 F5.3 mas/yr e_pml Standard error of proper motion in
Galactic longitude direction
107-112 F6.3 mas/yr pmb Proper motion in Galactic latitude direction
at Ep=2016.0
114-118 F5.3 mas/yr e_pmb Standard error of proper motion in
Galactic latitude direction
120-124 F5.3 [K] logTeff Median logarithm of the SED-fitted
effective temperature
126-130 F5.3 [K] b_logTeff 16th percentile logarithm of the SED-fitted
effective temperature from the
posterior distribution
132-136 F5.3 [K] B_logTeff 84th percentile logarithm of the SED-fitted
effective temperature from the
posterior distribution
138-142 F5.3 [Lsun] logLum Median logarithm of the SED-fitted luminosity
144-148 F5.3 [Lsun] b_logLum 16th percentile logarithm of the SED-fitted
luminosity from the posterior distribution
150-154 F5.3 [Lsun] B_logLum 84th percentile logarithm of the SED-fitted
luminosity from the posterior distribution
156-160 F5.3 [Msun] logMass Median logarithm of the SED-fitted mass
162-167 F6.3 [Msun] b_logMass 16th percentile logarithm of the SED-fitted
mass from the posterior distribution
169-173 F5.3 [Msun] B_logMass 84th percentile logarithm of the SED-fitted
mass from the posterior distribution
175-180 F6.3 mag AV Median extinction in the V-band
182-187 F6.3 mag b_AV 16th percentile of the extinction in the
V-band
189-194 F6.3 mag B_AV 84th percentile of the extinction in the
V-band
196-199 I4 pc Dist Median SED-fitted distance
201-204 I4 pc b_Dist 16th percentile SED-fitted distance from
the posterior distribution
206-209 I4 pc B_Dist 84th percentile SED-fitted distance from
the posterior distribution
211 A1 --- Group Group assigned to each star.
If set to N, the star belongs to no group
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Acknowledgements:
Alexis Quintana, a.l.p.quintana(at)keele.ac.uk
History:
22-Oct-2021: on-line version
24-Jan-2022: Galactic proper motions corrected (from author)
(End) Alexis Quintana [Keele, UK], Patricia Vannier [CDS] 20-Oct-2021