J/MNRAS/490/440 Gaia view of Cygnus OB2 and Carina OB1 associations (Lim+, 2019)
A Gaia view of the two OB associations Cygnus OB2 and Carina OB1:
the signature of their formation process.
Lim B., Naze Y., Gosset E., Rauw G.
<Mon. Not. R. Astron. Soc., 490, 440-454 (2019)>
=2019MNRAS.490..440L 2019MNRAS.490..440L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, OB ; Associations, stellar ; Spectral types ;
Parallaxes, trigonometric ; Proper motions ; Positional data ;
Optical
Keywords: stars: formation - stars: kinematics and dynamics -
open clusters and associations: individual: Cygnus OB2 and Carina OB1
Abstract:
OB associations are the prime star-forming sites in galaxies. However,
the detailed formation process of such stellar systems still remains a
mystery. In this context, identifying the presence of substructures
may help in tracing the footprints of their formation process. Here,
we present a kinematic study of the two massive OB associations Cygnus
OB2 and Carina OB1 using the precise astrometry from the Gaia Data
Release 2 and radial velocities. From the parallaxes of stars, these
OB associations are confirmed to be genuine stellar systems. Both
Cygnus OB2 and Carina OB1 are composed of a few dense clusters and a
halo which have different kinematic properties: the clusters occupy
regions of 5-8 parsecs in diameter and display small dispersions in
proper motion, while the haloes spread over tens of parsecs with two
to three times larger dispersions in proper motion. This is
reminiscent of the so-called line width-size relation of molecular
clouds related to turbulence. Considering that the kinematics and
structural features were inherited from those of their natal clouds
would then imply that the formation of OB associations may result from
structure formation driven by supersonic turbulence, rather than from
the dynamical evolution of individual embedded clusters.
Description:
The census of high-mass stars (O-, B-type stars, and Wolf-Rayet stars)
in Cyg OB2 and Car OB1 associations is more complete than those of the
low-mass star population. Such high-mass stars are brighter than
G∼16mag, and the Gaia DR2 provides very high-precision astrometric
data in that magnitude range (Gaia Collaboration, 2018A&A...616A...1G 2018A&A...616A...1G,
Cat. I/345). Therefore, we considered only the high-mass star
population of the associations in this study.
For Cyg OB2, a list of high-mass stars compiled by Wright et al.
(2015MNRAS.449..741W 2015MNRAS.449..741W, Cat. J/MNRAS/449/741) was used. This catalogue
contains the spectral types, the stellar parameters, and the
photometric data of 167 stars earlier than B5 taken from a number of
references (Table 1). For Car OB1, Naze et al. (2011ApJS..194....7N 2011ApJS..194....7N,
Cat. J/ApJS/194/7) studied 200 OB stars [70 O-type and 130 B-type,
compiled from Skiff (2009yCat....1.2023S 2009yCat....1.2023S, Cat. B/mk)]. In addition, we
added 106 OB stars from recent photometric or spectroscopic studies
(Hur, Sung & Bessell 2012AJ....143...41H 2012AJ....143...41H, Cat. J/AJ/143/41; Sota et
al. 2014ApJS..211...10S 2014ApJS..211...10S, Cat. III/274; Alexander et al.
2016AJ....152..190A 2016AJ....152..190A; Damiani et al. 2017A&A...603A..81D 2017A&A...603A..81D, Cat.
J/A+A/603/A81); Hanes, McSwain & Povich 2018AJ....155..190H 2018AJ....155..190H, Cat.
J/AJ/155/190). A total of 306 high-mass stars in Car OB1 were included
in the final list (Table 2).
Objects:
-----------------------------------------------------------------------
RA (ICRS) DE Designation(s)
-----------------------------------------------------------------------
20 33 11.99 +41 19 00.0 AssCygOB2 = 1E 2031.0+4050 = Ass Cyg OB 2
10 37 59.99 -58 59 59.9 AssCarOB1 = Ass Car OB 1
-----------------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 142 167 Catalogue of high-mass stars in Cygnus OB2
table2.dat 153 306 Catalogue of high-mass stars in Carina OB1
--------------------------------------------------------------------------------
See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/MNRAS/449/741 : The massive star population of Cygnus OB2 (Wright+, 2015)
J/ApJS/194/7 : X-ray properties of O and B stars in Carina (Naze+, 2011)
B/mk : Catalogue of Stellar Spectral Classifications
(Skiff, 2009- )
J/AJ/143/41 : UBVIc CCD photometry of star clusters Tr14 and Tr16
(Hur+, 2012)
III/274 : Galactic O-Star Spectroscopic Survey (GOSSS) (Sota+, 2014)
J/A+A/603/A81 : Trumpler 14 and 16 in the Carina nebula (Damiani+, 2017)
J/AJ/155/190 : Carina Nebula hot stars: stellar parameters and RVs
(Hanes+, 2018)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- ID [1/167] Internal object identifier
5- 6 I2 h RAh Right ascension (J2000)
8- 9 I2 min RAm Right ascension (J2000)
11- 15 F5.2 s RAs Right ascension (J2000)
17 A1 --- DE- Declination sign (J2000)
18- 19 I2 deg DEd Declination (J2000)
21- 22 I2 arcmin DEm Declination (J2000)
24- 27 F4.1 arcsec DEs Declination (J2000)
29- 44 A16 --- SpType Spectral type from
Wright et al. (2015MNRAS.449..741W 2015MNRAS.449..741W,
Cat. J/MNRAS/449/741)
46- 52 F7.4 mas plx ? Parallax from Gaia DR2
54- 59 F6.4 mas e_plx ? Error on plx
61- 67 F7.3 mas/yr pmRA ? Proper motion in right ascension from
Gaia DR2
69- 73 F5.3 mas/yr e_pmRA ? Error on pmRA
75- 81 F7.3 mas/yr pmDE ? Proper motion in declination from Gaia DR2
83- 87 F5.3 mas/yr e_pmDE ? Error on pmDE
89 I1 --- Dup [0/1]? Duplication flag from Gaia DR2
91- 97 F7.4 mag Gmag ? Gaia DR2 G-band magnitude
99-104 F6.4 mag e_Gmag ? Error on Gmag
106-112 F7.4 mag BPmag ? Gaia DR2 BP-band magnitude
114-119 F6.4 mag e_BPmag ? Error on BPmag
121-127 F7.4 mag RPmag ? Gaia DR2 RP-band magnitude
129-134 F6.4 mag e_RPmag ? Error on RPmag
136-142 F7.5 mag BP-RP ? Gaia DR2 BP-RP colour
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- ID [1/306] Internal object identifier
5- 6 I2 h RAh Right ascension (J2000)
8- 9 I2 min RAm Right ascension (J2000)
11- 15 F5.2 s RAs Right ascension (J2000)
17 A1 --- DE- Declination sign (J2000)
18- 19 I2 deg DEd Declination (J2000)
21- 22 I2 arcmin DEm Declination (J2000)
24- 27 F4.1 arcsec DEs Declination (J2000)
29- 53 A25 --- SpType Spectral type
55- 57 A3 --- r_SpType Reference for SpType (1)
59- 65 F7.4 mas plx ? Parallax from Gaia DR2
67- 72 F6.4 mas e_plx ? Error on plx
74- 80 F7.3 mas/yr pmRA ? Proper motion in right ascension from
Gaia DR2
82- 86 F5.3 mas/yr e_pmRA ? Error on pmRA
88- 92 F5.3 mas/yr pmDE ? Proper motion in declination from Gaia DR2
94- 98 F5.3 mas/yr e_pmDE ? Error on pmDE
100 I1 --- Dup [0/1]? Duplication flag from Gaia DR2
102-108 F7.4 mag Gmag ? Gaia DR2 G-band magnitude
110-115 F6.4 mag e_Gmag ? Error on Gmag
117-123 F7.4 mag BPmag ? Gaia DR2 BP-band magnitude
125-130 F6.4 mag e_BPmag ? Error on BPmag
132-138 F7.4 mag RPmag ? Gaia DR2 RP-band magnitude
140-145 F6.4 mag e_RPmag ? Error on RPmag
147-153 F7.4 mag BP-RP ? Gaia DR2 BP-RP colour
--------------------------------------------------------------------------------
Note (1): References as follows:
1 = Naze et al. (2011ApJS..194....7N 2011ApJS..194....7N, Cat. J/ApJS/194/7)
2 = Hur et al. (2012AJ....143...41H 2012AJ....143...41H, Cat. J/AJ/143/41)
3 = Damiani et al. (2017A&A...603A..81D 2017A&A...603A..81D, Cat. J/A+A/603/A81)
4 = Sota et al. (2014ApJS..211...10S 2014ApJS..211...10S, Cat. III/274)
5 = Alexander et al. (2016AJ....152..190A 2016AJ....152..190A)
6 = Hanes et al. (2018AJ....155..190H 2018AJ....155..190H, Cat. J/AJ/155/190)
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 24-Jan-2023