J/AJ/166/97 Radial velocities in W5 YSO groups (Lim+, 2023)
The Kinematics of the Young Stellar Population in the W5 Region of the
Cassiopeia OB6 Association: Implication for the Formation Process of Stellar
Associations.
Lim B., Hong J., Lee J., Yun H.-S., Hwang N., Park B.-G.
<Astron. J., 166, 97 (2023)>
=2023AJ....166...97L 2023AJ....166...97L
ADC_Keywords: Associations, stellar; Star Forming Region; YSOs;
Spectra, optical; Radial velocities
Keywords: Star formation ; Stellar kinematics ; Stellar associations ;
Stellar dynamics ; Open star clusters
Abstract:
The star-forming region W5 is a major part of the Cassiopeia OB6
association. Its internal structure and kinematics may provide hints
of the star formation process in this region. Here, we present a
kinematic study of young stars in W5 using the Gaia data and our
radial velocity data. A total 490 out of 2000 young stars are
confirmed as members. Their spatial distribution shows that W5 is
highly substructured. We identify a total of eight groups using the
k-means clustering algorithm. There are three dense groups in the
cavities of H ii bubbles, and the other five sparse groups are
distributed at the edges of the bubbles. The three dense groups have
almost the same age (5Myr) and show a pattern of expansion. The scale
of their expansion is not large enough to account for the overall
structure of W5. The three northern groups are, in fact, 3Myr younger
than the dense groups, which indicates independent star formation
events. Only one of these groups shows the signature of feedback-
driven star formation as its members move away from the eastern dense
group. The other two groups might have formed in a spontaneous way. On
the other hand, the properties of two southern groups are not
understood as those of a coeval population. Their origins can be
explained by dynamical ejection of stars and multiple star formation.
Our results suggest that the substructures in W5 formed through
multiple star-forming events in a giant molecular cloud.
Description:
We performed multiobject spectroscopic observations of YSO candidates
on 2020 September 3, October 30, and 2021 October 22, 27, and 29 using
the high-resolution (R∼34000) multiobject spectrograph Hectochelle on
the 6.5m telescope of the MMT observatory. All the spectra were taken
with the RV31 filter, which covers the spectral range 5150-5300Å in
a 2x2 binning mode.
Objects:
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RA (2000) DE Designation(s)
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02 51 25.20 +60 25 08.3 W5 = C 0247+602
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 124 490 List of members
table2.dat 75 8 Properties of individual groups
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See also:
B/mk : Catalogue of Stellar Spectral Classifications (Skiff, 2009- )
B/simbad : Simbad objects catalogue (M.Wenger 2000)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
V/125 : Photometry and Spectroscopy for Luminous Stars (Reed 2005)
J/AJ/128/805 : Low-mass stars in Cepheus OB2 region (Sicilia-Aguilar+ 2004)
J/ApJS/160/319 : COUP; observations and source lists (Getman+, 2005)
J/A+A/455/903 : ACIS-I observations of NGC 2264 (Flaccomio+, 2006)
J/ApJ/639/1069 : Radial velocities in the CasOB6 association (Hillwig+, 2006)
J/A+A/472/835 : JHKs and GLIMPSE photometry of RCW 120 (Zavagno+, 2007)
J/ApJ/688/1142 : Star formation in W5; Spitzer observations (Koenig+, 2008)
J/MNRAS/415/1202 : BVI photometry in W5E HII region (Chauhan+, 2011)
J/ApJ/726/18 : Young intermediate-mass stars in W5 (Koenig+, 2011)
J/A+A/539/A74 : NGC1893 Chandra X-ray catalog (Caramazza+, 2012)
J/ApJ/787/107 : Spatial structure of young stellar clusters I. (Kuhn+, 2014)
J/MNRAS/438/1451 : UBVIHα photometry of IC 1848 (Lim+, 2014)
J/MNRAS/443/454 : UBVIHα photometry in NGC 1893 (Lim+, 2014)
J/MNRAS/477/1993 : NGC 1893 stars LSR velocities (Lim+, 2018)
J/ApJS/236/51 : PGCCs in lambda Orionis complex. II. Cores 850um (Yi+, 2018)
J/ApJ/870/32 : Kinematics young star clusters & associations (Kuhn+, 2019)
J/MNRAS/490/440 : Gaia view of Cygnus OB2 & Carina OB1 assoc (Lim+, 2019)
J/ApJS/244/28 : The 3rd MSFRs Omnibus X-ray Catalog (Townsley+, 2019)
J/ApJ/899/121 : 127 early type & pre-main-sequence stars in W4 (Lim+, 2020)
J/MNRAS/495/663 : Gaia DR2 OB associations (Ward+, 2020)
J/AJ/162/56 : Radial velocity of 240 YSO with MMT/Hectochelle (Lim+, 2021)
J/ApJS/254/14 : Planck Cold Clumps lambda Orionis complex. III. (Yi+, 2021)
J/AJ/163/266 : IGRINS & Gaia; star formation Monoceros OB1 &R1 (Lim+, 2022)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/490] Sequential identifier
5- 13 F9.6 deg RAdeg [41/46] Right Ascension (J2000)
15- 23 F9.6 deg DEdeg [59/62] Declination (J2000)
25- 30 F6.4 mas plx [0.28/0.99] Gaia EDR3 parallax
32- 37 F6.4 mas e_plx [0.01/0.4] Uncertainty in plx
39- 44 F6.3 mas/yr pmRA [-2.1/1.45] Gaia EDR3 proper motion in RA
46- 50 F5.3 mas/yr e_pmRA [0.01/0.3] Uncertainty in pmRA
52- 57 F6.3 mas/yr pmDE [-2.13/1.44]? Gaia EDR3 proper motion in DE
59- 63 F5.3 mas/yr e_pmDE [0.01/0.4] Uncertainty in pmDE
65- 71 F7.3 km/s RVel [-54.1/-5.06]? Heliocentric radial velocity
73- 79 F7.3 km/s RV-LSR [-51.1/-1.99]? Radial velocity in the local
standard of rest frame
81- 85 F5.3 km/s e_RVel [0.2/5]? Uncertainty in Radial Velocity
87- 93 F7.4 mag Gmag [7.81/19.2] Gaia EDR3 G-band magnitude
95-101 F7.4 mag BPmag [7.99/20.9] Gaia EDR3 BP-band magnitude
103-109 F7.4 mag RPmag [7.46/18] Gaia EDR3 RP-band magnitude
111-116 F6.4 mag BP-RP [0.48/4.32] Gaia EDR3 BP-RP color
118-122 A5 --- Remark Remarks (1)
124-124 A1 --- Group Group (Table 2)
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Note (1): Classification of young stars ; 'E' represents O- or B-type
stars obtained from the data bases of MK classification. 'H' and 'h'
are Hα emission stars and Hα emission star candidates,
respectively. '1', '2', and 'T' denote Class I, Class II, and YSOs
with a transitional disk, respectively.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 1 A1 --- Group Group
3- 11 F9.6 deg RAdeg [41/46] Median group Right Ascension (J2000)
13- 21 F9.6 deg DEdeg [59/61] Median group Declination (J2000)
23- 28 F6.3 mas/yr pmRA [-0.62/0.21] Median group proper motion in RA
30- 35 F6.3 mas/yr pmDE [-0.64/-0.03] Median group proper motion in DE
37- 40 F4.1 km/s VT-RA [-6.1/2] Median tangential velocity in RA
42- 45 F4.1 km/s VT-DE [-6.3/-0.4] Median tangential velocity in DE
47- 51 F5.1 km/s RV-LSR [-39.2/-29.1]? Median Radial velocity in the
local standard of rest frame
53- 55 F3.1 km/s sigVT-RA [2.4/6.9] Dispersion of tangential velocity
along RA
57- 59 F3.1 km/s sigVT-DE [2/8.7] Dispersion of tangential velocity
along DE
61- 63 F3.1 km/s sigRV-LSR [0.6/3.5]? Dispersion of RV-LSR
65- 67 I3 --- Ngrp [10/159] number of group members
69- 70 I2 --- Nrv [0/25] number of group members with RV
72- 75 F4.2 --- MST [0.62/1.73] minimum spanning tree
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 20-Mar-2024