J/MNRAS/508/4952 OB stars in Carina Arm (Drew+, 2021)
Proper motions of OB stars in the far Carina Arm.
Drew J.E., Monguio M., Wright N.J.
<Mon. Not. R. Astron. Soc. 508, 4952-4968>
=2021MNRAS.508.4952D 2021MNRAS.508.4952D (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, OB ; Stars, early-type ; Clusters, open ;
Associations, stellar ; Positional data ; Photometry ; Infrared ;
Optical ; Effective temperatures ; Extinction ; Spectral types ;
Parallaxes, trigonometric ; Proper motions ; Stars, distances ;
Radial velocities
Keywords: stars: early-type -
(Galaxy:) open clusters and associations: NGC 3603 -
Galaxy: structure - surveys
Abstract:
In large-scale maps of the Galactic disc, the Carina Arm stands out as
a clear spiral feature, hosting prominent star clusters and
associations rich in massive stars. We study the proper motions of
4199 O and early B most likely in the far Carina Arm, at distances
mainly in excess of 4 kpc from the Sun, within the sky region,
282°< l < 294° and -3° < b < +1° (Galactic
coordinates). The sample is constructed by extending an existing
blue-selected catalogue, and cross-matching with Gaia EDR3 astrometry.
The observed pattern of proper motions is modulated into a saw-tooth
pattern, with full amplitude approaching 1 mas/yr, recurring roughly
every 2-3 degrees of longitude (200-300 pc at the median OB-star
distance of 5.8 kpc). Kinematic perturbation of underlying circular
rotation is most likely present. The data also reveal a moving group
containing >50 OB stars at l ∼ 286°, b ∼ -1.4° behind the main
run of the far arm. An analysis of relative proper motions is
performed that yields an incidence of runaway O stars of at least 10
per cent (potentially >20 per cent when full space motions become
available). To map where runaways have run away from, we set up
simulations for the region that assume linear trajectories and test
for trajectory impact parameter in order to identify likely ejection
hot spots. We find the method currently gives good results for times
of flight of up to ∼4 Myr. It shows convincingly that only NGC 3603
and Westerlund 2 have ejected OB stars in significant numbers. Indeed,
both clusters have experienced intense spells of ejection between
0.6-0.9 and 0.5-0.8 Myr ago, respectively.
Description:
This study follows on from three pieces of work. The first of them by
Mohr-Smith et al. (2017MNRAS.465.1807M 2017MNRAS.465.1807M, Cat. J/MNRAS/465/1807)
provides a large photometrically identified and spectroscopically
tested catalogue of Carina OB stars that we re-use and add to here.
Since this appeared, we have already made use of it in searching the
environs of the massive young clusters, NGC 3603 and Westerlund 2, for
runaway O stars Drew et al. (2019MNRAS.486.1034D 2019MNRAS.486.1034D, Cat.
J/MNRAS/486/1034); Drew et al. (2018MNRAS.480.2109D 2018MNRAS.480.2109D). Proper motions
from Gaia DR2 astrometry were key to both searches.
The extraction of a far Carina Arm sample of 4199 OB stars from a
cross-match between an extended version of the Mohr-Smith et al.
(2017MNRAS.465.1807M 2017MNRAS.465.1807M, Cat. J/MNRAS/465/1807) catalogue separated
'good' OB star candidates from the more questionable by requiring
Χ2 < 7.82 and Gaia EDR3 as described in section 2 Construction
of the sample. Their physical and positional properties are presented
in the tablea1.dat.
Further in this study, we focus on the far-arm sample focusing on open
clusters like NGC 3603 and Westerlund 2 (i.e see section 3 Overview of
the far-arm sample and section 4 The frequency of high relative proper
motion massive stars). Especially in this investigation, (i.e section
4.3 The most extreme relative proper motion objects) we briefly
comment on the five most extreme objects in their high relative
tangential speeds and extreme relative proper motions. Properties of
these 5 stars are available in the table2.dat.
Hereafter, in the section 5 (Connecting runaway candidates to places
of origin in the far-arm region) we presente analysis method and
simulations based on impact parameter criteria for revisiting the NGC
3603 and Westerlund 2 open clusters previous studies made by Drew et
al. (2019MNRAS.486.1034D 2019MNRAS.486.1034D, Cat. J/MNRAS/486/1034) and Drew et al.
(2018MNRAS.480.2109D 2018MNRAS.480.2109D). In the table4.dat, we regroup data on candidate
OB-star ejections from these 2 cluters. These candidates has been
selected throughout criteria on position, impact parameter, time of
flight and relative proper motions.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 771 4199 *Our fits-formatted OB-candidates list of
the 4199 stars
table2.dat 91 5 The five most extreme objects in the sample
with extreme |µrel|, high vt,rel>100 km/s,
good parallaxes π/σ < 5 and trustworthy
SED fits Χ2 < 7.82
table4.dat 119 34 Data on candidate OB-star ejections from
NGC 3603 and Westerlund 2
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Note on tablea1.dat: We use properties from Gaia EDR3 (Gaia Collaboration
2021A&A...649A...1G 2021A&A...649A...1G, Cat. I/350), 2MASS Cutri et al. (2003, Cat. II/246) and
VPHAS+ DR2 survey Drew et al. (2016, Cat. II/341).
--------------------------------------------------------------------------------
See also:
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/MNRAS/465/1807 : Deep OB star population in Carina (Mohr-Smith+, 2017)
II/341 : VPHAS+ DR2 survey (Drew+, 2016)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/MNRAS/486/1034 : O stars of the Galactic starburst NGC 3603 (Drew+,2019)
J/A+A/624/A66 : Massive runaway and walkaway stars models (Renzo+,2019)
J/A+A/530/A108 : VLT-FLAMES Tarantula Survey (Evans+, 2011)
J/ApJ/867/108 : Stellar masses and rest-frame u-g colors of SNIa
(Jones+, 2018)
J/ApJ/903/43 : Kinematic & fundamental parameters; OB stars
(Dorigo Jones+, 2020)
J/other/NewAR/90.1549 : Catalogue of OB Associations (Wright, 2020)
J/A+A/650/A112 : Mapping hot luminous stars in the Galaxy (Zari+, 2021)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- ID VPHAS-OBM-NNNNN, where NNNNN is ordered by
Galactic longitude and M is 1 or 2 (ID)
17- 32 F16.12 deg RAdeg Right Ascension VPHAS+ (J2000) (RA)
34- 50 F17.13 deg DEdeg Declination VPHAS+ (J2000) (DEC)
52- 67 F16.12 deg GLON Galactic longitude (GAL_LONG)
69- 86 F18.15 deg GLAT Galactic latitude (GAL_LAT)
88-103 F16.13 mag umag u-band magnitude (Vega) from VPHAS+ (u)
105-121 F17.15 mag e_umag u-band photometric uncertainty VPHAS+ (u_err)
123-138 F16.13 mag gmag g-band magnitude (Vega) from VPHAS+ (g)
140-156 F17.15 mag e_gmag g-band photometric uncertainty VPHAS+ (g_err)
158-173 F16.13 mag rmag r-band magnitude (Vega) from VPHAS+ (r)
175-191 F17.15 mag e_rmag r-band photometric uncertainty VPHAS+ (r_err)
193-208 F16.13 mag imag i-band magnitude (Vega) from VPHAS+ (i)
210-226 F17.15 mag e_imag i-band photometric uncertainty VPHAS+ (i_err)
228-233 F6.3 mag Jmag J-band 2MASS magnitude (Vega) (J)
235-239 F5.3 mag e_Jmag J-band photometric uncertainty 2MASS (J_err)
241-246 F6.3 mag Hmag H-band 2MASS magnitude (Vega) (H)
248-252 F5.3 mag e_Hmag H-band photometric uncertainty 2MASS (H_err)
254-259 F6.3 mag Kmag K-band 2MASS magnitude (Vega) (K)
261-265 F5.3 mag e_Kmag K-band photometric uncertainty 2MASS (K_err)
267-282 F16.14 [K] logTeff Effective temperature from photometric fits
(median of posterior) (logTeff)
284-300 F17.15 [K] logTeff84 Upper uncertainty on logTeff 84th percentile
of posterior (logteffeuc)
302-318 F17.15 [K] logTeff16 Upper uncertainty on logTeff 16th percentile
of posterior (logteffelc)
320-336 F17.14 mag A0 Estimated extinction, A0, from photometric
fits (median of posterior) (A0)
338-354 F17.14 mag A0err84 Upper uncertainty on A0 84th percentile
of posterior (A0_eu)
356-371 F16.14 mag A0err16 Upper uncertainty on A0 16th percentile
of posterior (A0_el)
373-388 F16.14 --- Rv Photometric estimation for the extinction
law parameter (RV)
390-405 F16.14 --- Rverr84 Upper uncertainty on RV 84th percentile
of posterior (Rv_eu)
407-422 F16.14 --- Rverr16 Upper uncertainty on RV 16th percentile
of posterior (Rv_el)
424-440 F17.14 --- Chi2 Χ2 value for photometric fit as
a measure of fit quality (Χ2)
442 I1 --- EMstar Indicates if star is selected
as an emission line object (EM_star)
444-477 A34 --- Notes Alternate names of objects already
in the literature (Notes)
479-507 A29 --- GaiaEDR3 Gaia EDR3 identifier (EDR3Name)
509-526 F18.15 mas Plx Gaia EDR3 absolute parallax
at the Ep=2016.0 (Plx)
528-535 F8.6 mas e_Plx Uncertainty in parallax
at the Ep=2016.0 (e_Plx)
537-554 F18.14 mas/yr pmRA Proper motion in right ascension pmRA*cosDE
of the source in ICRS at Ep=2016.0 (pmRA)
556-563 F8.6 mas/yr e_pmRA Uncertainty in proper motion in right
ascension direction (e_pmRA)
565-581 F17.14 mas/yr pmDE Proper motion in declination
direction (pmDE)
583-590 F8.6 mas/yr e_pmDE Uncertainty proper motion
in declination direction (e_pmDE)
592-603 F12.9 mas/yr pmRApmDEc Cross-correlation term between proper motion
in right ascension and proper motion
in declination (pmRApmDEcor)
605-614 F10.8 --- RUWE Renormalized unit weight error
from Gaia EDR3 (RUWE)
616-625 F10.7 mag Gmag Gaia G band in Vega system (Gmag)
627-643 F17.15 mag e_Gmag Gaia G-band photometric uncertainty
in Vega system (e_Gmag)
645-661 F17.14 pc D2.0 Estimated distance (D_2.0) (1)
663-679 F17.14 pc D2.0low Lower bound on distance
5th percentile of posterior (D2.0p5)
681-697 F17.14 pc D2.0high Upper bound on distance
95th percentile of posterior (D2.0p95)
699-716 F18.14 mas/yr pmGLON Longitudinal proper motion (pml)
718-734 F17.15 mas/yr e_pmGLON Uncertainty in longitudinal
proper motion (e_pml)
736-753 F18.15 mas/yr pmGLAT Latitudinal proper motion (pmb)
755-771 F17.15 mas/yr e_pmGLAT Uncertainty in latitudinal
proper motion (e_pmb)
--------------------------------------------------------------------------------
Note (1): We compute these via the EDSD method presented by Luri et al.
(2018A&A...616A...9L 2018A&A...616A...9L, Cat. I/345). EDSD inversion offset 0.03 mas,
length scale 2000 pc.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- ID VPHAS-OBM-NNNNN where NNNNN is Galactic
longitude ordered sequence number taken
from M17 and Gaia EDR3 (Cat) (1)
17- 25 F9.5 deg GLON Galactic longitude (GAL_LONG)
27- 34 F8.5 deg GLAT Galactic latitude (GAL_LAT)
36- 40 F5.3 [K] logTeff Effective temperature from photometric fits
(median of posterior) (logTeff)
42- 45 F4.2 --- Chi2 Χ2 value for photometric fit as
a measure of fit quality (Χ2)
47- 53 F7.5 mas Plx Absolute parallax π (π)
55- 59 F5.2 --- Plxratio Ratio π/σ (π/σ)
61- 64 F4.2 kpc D2.0 Estimated distance (D_2.0) (2)
66- 68 F3.1 kpc D2.0low Lower bound on distance 16th percentile
of posterior (D2.0p16)
70- 72 F3.1 kpc D2.0high Upper bound on distance 84th percentile
of posterior (D2.0p84)
74- 78 F5.2 mas/yr pmrel Relative to the median proper motion
(|µrel|)
80- 83 F4.2 mas/yr e_pmrel Mean error on relative to the median
proper motion (|µrel|err)
85- 87 I3 km/s Vtrel Relative tangential velocities (vt,rel)
89- 91 I3 km/s Vtrelmin Lower limit of the relative tangential
velocities (vt,relmin)
--------------------------------------------------------------------------------
Note (1): The first catalogue is Mohr-Smith et al. (2017MNRAS.465.1807M 2017MNRAS.465.1807M,
Cat. J/MNRAS/465/1807) and the second is Gaia EDR3 (Gaia Collaboration
2021A&A...649A...1G 2021A&A...649A...1G, Cat. I/350).
Note (2): We compute these via the EDSD method presented by Luri et al.
(2018A&A...616A...9L 2018A&A...616A...9L, Cat. I/345). EDSD inversion offset 0.03 mas,
length scale 2000 pc.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Cluster Open cluster name (Cluster)
14- 28 A15 --- ID VPHAS-OBM-NNNNN where NNNNN is Galactic
longitude ordered sequence number taken
from M17 and Gaia EDR3 (Cat) (1)
30- 48 I19 --- GaiaEDR3 ID Gaia EDR3 (GaiaEDR3_ID)
50- 56 F7.3 deg GLON Galactic longitude (GAL_LONG)
58- 63 F6.3 deg GLAT Galactic latitude (GAL_LAT)
65- 69 F5.1 arcmin |r| Modulus of the position vector between
the star and adopted centre in the plane
of the sky (|r|)
71- 74 F4.2 arcmin p The impact parameter (p) (2)
76- 79 F4.2 arcmin e_p Mean error on p (e_p)
81- 85 F5.2 mas/yr pmrel Relative to the median proper motion
(|µrel|) (3)
87- 90 F4.2 mas/yr e_pmrel Mean error on relative to the median
proper motion (|µrel|err)
92- 95 F4.2 Myr Deltat Estimated time of flight (Δt) (4)
97-100 F4.2 Myr e_Deltat Mean error on Δt (e_Δt) (4)
102-105 F4.2 kpc D2.0 Estimated distance (D_2.0) (5)
107-109 F3.1 kpc D2.0low Lower bound on distance 16th percentile
of posterior (D2.0p16)
111-114 F4.1 kpc D2.0high Upper bound on distance 84th percentile
of posterior (D2.0p84)
116-117 A2 --- SpType Spectral type (Type) (6)
119 A1 --- Run [Y/N] Object already identified as
a likely runaway (Runaway) (7)
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Note (1): The first catalogue is Mohr-Smith et al. (2017MNRAS.465.1807M 2017MNRAS.465.1807M,
Cat. J/MNRAS/465/1807) and the second is Gaia EDR3 (Gaia Collaboration
2021A&A...649A...1G 2021A&A...649A...1G, Cat. I/350).
Note (2): For every star in the selection of higher |µrel| objects,
the impact parameter, p, of the on-sky trajectory with respect to the
reference position is determined from |r|*sin(θ), where r is the
position vector between the star and adopted centre in the plane of
the sky, while θ is the angle between vector µrel and
vector r in radians.
Note (3): For NGC 3603 (D2.0 = 6.91 kpc), the minimum relative proper
motion |µrel| required of ejection candidates is 0.6 mas/yr.
This was increased to 0.9 mas/yr.
Note (4): A further quantity collected in the simulations is the time of flight,
Δt, for each candidate runaway from its point of origin. We set
an upper limit on it, and include it as a constraint alongside the
constraints on p and |µrel|. Querying for time of flight proxies
in a more astronomically-relevant way for the angular range searched
on sky. The Δt limits we favour are 2 and 4 Myr, the former
being a rough upper bound on the ages of NGC 3603, and also
Westerlund 2. The errors on Δt include contributions from the
uncertainty in |µrel| and a generous fixed error of 1.0 arcmin
in |r| that acknowledges our ignorance of the exact point of ejection
within either cluster.
Note (5): We compute these via the EDSD method presented by Luri et al.
(2018A&A...616A...9L 2018A&A...616A...9L, Cat. I/345). EDSD inversion offset 0.03 mas,
length scale 2000 pc.
Note (6): The spectral type are as follows:
O = O stars
B = B stars
EM = Emission line objects
Note (7): Indicates whether the object was already identified previously as a
likely runaway by either Drew et al. (2018MNRAS.480.2109D 2018MNRAS.480.2109D) for
Westerlund 2 or by Drew et al. (2019MNRAS.486.1034D 2019MNRAS.486.1034D,
Cat. J/MNRAS/486/1034) for NGC 3603.
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(End) Luc Trabelsi [CDS] 03-Sep-2024