J/MNRAS/515/5993 Spectroscopic study of OB stars in Carina Arm (Drew+, 2022)
Radial velocities from far-red spectra of Carina Arm O and early B stars.
Drew J.E., Blake-Parsons F., Mohr-Smith M.
<Mon. Not. R. Astron. Soc. 515, 5993-6006 (2022)>
=2022MNRAS.515.5993D 2022MNRAS.515.5993D (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, OB ; Spectra, optical ; Positional data ;
Photometry ; Spectroscopy ; Optical ; Effective temperatures ;
Extinction ; Radial velocities ; Rotational velocities ;
Parallaxes, trigonometric ; Proper motions ; Stars, distances ;
Space velocities
Keywords: stars: early-type - stars: kinematics and dynamics - stars: massive -
Galaxy: kinematics and dynamics -
open clusters and associations: general
Abstract:
Massive O and early B stars are important markers of recent star
formation and exert a significant influence on their environments
during their short lives via photoionization and winds and when they
explode as supernovae. In the Milky Way, they can be detected at great
distances but often lie behind large dust columns, making detection at
short wavelengths difficult. In this study, the use of the less
extinguished far-red spectrum (8400-8800 Å) for radial velocity
measurement is examined. Results are reported for a sample of 164
confirmed OB stars within a 2° field positioned on the Carina Arm.
Most stars are at distances between 3 and 6 kpc, and Westerlund 2 is
at the field edge. The measured radial velocities have errors
concentrated in the 3-10 km.s-1 range, with a systematic uncertainty
of 2-3 km.s-1. These are combined with Gaia-mission astrometry to
allow full space motions to be constructed. Up to 22 stars are likely
to be runaways, although 8 of them are as likely to be interloping (so
far undetected) binaries. The mean azimuthal motion of the sample fits
in with recent measurements of Galactic disc rotation. In the
Galactocentric radial direction, the mean motion indicates modest
infall at a speed of ∼10 km.s-1. This experiment shows that weak
Paschen lines in the far-red can yield credible radial velocity
determination, offering the prospect of exploring OB-star kinematics
over much more of the Galactic disc than has hitherto been possible.
Description:
Massive O and early B stars are important determinants of galactic
evolution as providers of both ionizing and bulk kinetic energy. They
are also the pre-eminent markers of recent star formation events,
thanks to their short lifetimes of a few million years. The spectra
measured in this study were obtained as part of an investigation aimed
at confirming the photometric selection techniques behind a new
catalogue of 5915 Carina Arm O-B2 stars (Mohr-Smith et al.
(2017MNRAS.465.1807M 2017MNRAS.465.1807M, Cat. J/MNRAS/465/1807). These given 164 stars
have well-enough exposed spectra to support RV measurement.
Observations were done with the the AAT on 2014 June 18 and July 3. In
section 2.3, we expose astrometric, photometric and spectroscopic
requirements of our sample. Here we provide results as well as the 164
spectra used for result extraction methods. The table1.dat contains
astrometric, photometric and spectroscopic results as RV values.
Objects:
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RA (2000) DE Designation(s)
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10 00 00.00 -60 00 00.0 Car Arm = NAME Car Arm
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 638 164 Parameters and measurements of our stars sample
spectrum/* . 164 Individual far-red spectrum of OB stars
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See also:
J/MNRAS/465/1807 : Deep OB star population in Carina (Mohr-Smith+, 2017)
II/341 : VPHAS+ DR2 survey (Drew+, 2016)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
J/MNRAS/485/2312 : Outer Galactic disk A and F stars space motions
(Harris+, 2019)
J/ApJ/885/131 : ∼200 high-mass SFR plx & proper motion with VLBI
(Reid+, 2019)
J/MNRAS/450/3855 : New OB star candidates in Carina Arm (Mohr-Smith+, 2015)
J/MNRAS/508/4952 : OB stars in Carina Arm (Drew+, 2021)
J/MNRAS/486/1034 : O stars of the Galactic starburst NGC 3603 (Drew+, 2019)
Byte-by-byte Description of file: spectrum/*
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Bytes Format Units Label Explanations
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1- 18 F18.11 0.1nm Wavelength Spectroscopic measured wavelength
(Wavelength)
20- 37 F18.11 ct Count ? Number of counts (Count)
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Star name designation as (VPHASOENNNNN)
(Starname)
17- 26 F10.6 deg RAdeg Right Ascension (J2000) (RA_J2000)
28- 37 F10.6 deg DEdeg Declination (J2000) (DEC_J2000)
39- 48 F10.6 deg GLON Galactic longitude in IAU 1958 system
(GLON)
50- 58 F9.6 deg GLAT Galactic latitude in IAU 1958 system
(GLAT)
60- 65 F6.3 mag gmag The g band AB magnitude from VPHAS OB
star catalogue of Mohr-Smith
(2017MNRAS.465.1807M 2017MNRAS.465.1807M,
Cat. J/MNRAS/465/1807) (g)
67- 71 F5.3 mag e_gmag Mean random error of gmag (e_g)
73- 88 F16.14 [K] log(Teff) Estimated median 50th percentile
effective temperature from photometry
(logTeff)
90-106 F17.15 [K] E_log(Teff) Upper uncertainty 84th percentile of
log (Teff) (eu_logTeff)
108-124 F17.15 [K] e_log(Teff) Lower uncertainty 16th percentile of
log (Teff) (el_logTeff)
126-130 F5.3 mag A0 Estimated median 50th percentile
extinction from photometry (A0)
132-136 F5.3 mag E_A0 Upper uncertainty 84th percentile of
A0 (eu_A0)
138-142 F5.3 mag e_A0 Lower uncertainty 16th percentile of
A0 (el_A0)
144-148 F5.3 --- Rv Estimated median 50th percentile
extinction law paremeter from photometry
(Rv)
150-154 F5.3 --- E_Rv Upper uncertainty 84th percentile of
Rv (eu_Rv)
156-160 F5.3 --- e_Rv Lower uncertainty 16th percentile of
Rv (el_Rv)
162-177 F16.14 [K] log(Teff)sp ? Estimated median 50th percentile
effective temperature from spectroscopy
(speclogTeff)
179-195 F17.15 [K] E_log(Teff)sp ? Upper uncertainty 84th percentile of
log(Teff)sp (eu_speclogTeff)
197-213 F17.15 [K] e_log(Teff)sp ? Lower uncertainty 16th percentile of
log(Teff)sp (el_speclogTeff)
215-230 F16.14 [cm/s2] log(g)sp ? Estimated median 50th percentile
surface gravity from spectroscopy (logg)
232-248 F17.15 [cm/s2] E_log(g)sp ? Upper uncertainty 84th percentile of
log(g)sp (eu_logg)
250-266 F17.15 [cm/s2] e_log(g)sp ? Lower uncertainty 16th percentile of
log(g)sp (el_logg)
268-270 I3 km/s vsini ? Estimated median 50th percentile
projected rotation speed (vsini)
272-274 I3 km/s E_vsini ? Upper uncertainty 84th percentile of
vsini (eu_vsini)
276-278 I3 km/s e_vsini ? Lower uncertainty 16th percentile of
vsini (el_vsini)
280-287 F8.3 0.1nm LambdaPa12 Spectroscopic measured Paschen 12 line
from combined Pa12 and Pa13 fits
(Pa_lambda)
289-293 F5.3 0.1nm e_LambdaPa12 Fit uncertainty of LambdaPa12
(ePalambda)
295-313 F19.15 km/s RVPa Heliocentric radial velocity from
LambdaPa12 measurements (Pavelhc)
315-331 F17.14 km/s e_RVPa Mean error of RVPa (ePavel_hc)
333-351 I19 --- GaiaEDR3 Gaia EDR3 source identifier number
(EDR3Name)
353-358 F6.4 mas Plx Parallax from Gaia EDR3 (Plx)
360-365 F6.4 mas e_Plx Uncertainty of Plx (e_Plx)
367-373 F7.4 --- Plx/e_Plx Parallax to uncertainty ratio (RPlx)
375-380 F6.3 mas/yr pmRA Proper motion in right ascension from
Gaia EDR3 (pmRA)
382-386 F5.3 mas/yr e_pmRA Uncertainty of pmRA (e_pmRA)
388-392 F5.3 mas/yr pmDE Proper motion in declination from
Gaia EDR3 (pmDE)
394-398 F5.3 mas/yr e_pmDE Uncertainty of pmDE (e_pmDE)
400-416 F17.14 mas/yr pml Galactic longitudinal proper motion (pml)
418-434 F17.15 mas/yr e_pml Uncertainty of pml (e_pml)
436-453 F18.15 mas/yr pmb Galactic latitudinal proper motion (pmb)
455-471 F17.15 mas/yr e_pmb Uncertainty of pmb (e_pmb)
473-489 F17.14 kpc D Estimated median 50th distance from EDSD
method with an offset 0.030 mas and a
length scale of 2.0 kpc (D_2.0) (1)
491-507 F17.15 kpc E_D Upper uncertainty 84th percentile of
D (euD2.0)
509-526 F18.15 kpc e_D [] Lower uncertainty 16th percentile of
D (elD2.0)
528-546 F19.15 km/s vR Galactocentric radial velocity (v_R)
548-564 F17.14 km/s e_vR Error of vR (evr)
566-581 F16.12 km/s vphi Galactocentric azimuthal velocity (v_phi)
583-599 F17.14 km/s e_vphi Error of vphi (evphi)
601-619 F19.15 km/s vz Galactocentric out of the galactic plane
velocity (v_z)
621-638 F18.15 km/s e_vz Error of vz (evz)
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Note (1): As described by Luri et al. (2018A&A...616A...9L 2018A&A...616A...9L).
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History:
From electronic version of the journal
(End) Luc Trabelsi [CDS] 09-Jul-2025