J/ApJ/902/62 WR 121-16: a new Wolf-Rayet WN/C star in the MW (Zhang+, 2020)
A new transition Wolf-Rayet WN/C star in the Milky Way.
Zhang W., Todt H., Wu H., Shi J., Hsia C.-H., Wu Y., Wu C., Zhao Y.,
Zhang T., Hou Y.
<Astrophys. J., 902, 62 (2020)>
=2020ApJ...902...62Z 2020ApJ...902...62Z
ADC_Keywords: Stars, Wolf-Rayet; Spectra, optical; Milky Way
Keywords: Wolf-Rayet stars ; Massive stars ; Stellar distance ;
Galaxy stellar content
Abstract:
We report the discovery of a new transition type Wolf-Rayet (W-R) WN/C
star in the Galaxy. According to its coordinates
RAJ2000=18:51:39.7,DEJ2000=-05:34:51.1, and the distance
(7.11-1.22+1.56kpc away from Earth) inferred from the second Gaia
data release, it is found that W-R 121-16 is located in the Far 3kpc
Arm, and it is 3.75kpc away from the Galactic Center. The optical
spectra obtained by the Large Sky Area Multi-Object Fiber
Spectroscopic Telescope and the 2.16m telescope, both located at the
Xinglong Observatory in China, indicate that this is a W-R star of the
transitional WN7o/WC subtype. A current stellar mass of about
7.1-1.1+1.7M☉, a mass- loss rate of
dM/dt=10-4.97(-0.20+0.16)M☉/yr, a bolometric luminosity of
log L/L☉=4.88-0.15+0.17, and a stellar temperature of
T*=47-5+9kK are derived by fitting the observed spectrum with a
specific Potsdam W-R model. The magnitude in V-band varies between
13.95 and 14.14mag, while no period is found. Based on the optical
spectra, the time domain data, and the indices of the astrometric
solution of the Gaia data, W-R 121-16 is likely a transitional WN/C
single star rather than a WN+WC binary.
Description:
The LAMOST low-resolution (R∼1800) spectrum of WR 121-16 obtained on
2014 September 9, with an exposure time of 1800s, shows strong
nitrogen lines, such as NIIIλ4634-λ4641 blend,
NIVλ4057, λ7109, λ7123. The HeI and HeII lines
are also strong. The CIVλ5808 line is strong, while
CIIIλ5696 line cannot be detected.
We also carried out the followup observations using the BAO Faint
Object Spectrograph and Camera (BFOSC) on the 2.16m telescope at the
Xinglong Observatory in China on 2019 October 30 and 31, with an
exposure time of 1200s on each night (spectral coverage roughly from
3250 to 8850Å with a resolving power R∼1600).
Objects:
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RA (ICRS) DE Designation(s)
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18 51 39.71 -05 34 51.1 WR 121-16 = ASASSN-V J185139.71-053451.1
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
bfosc30.dat 23 2048 BFOSC/2.16m telescope spectrum from 2019-10-30
bfosc31.dat 23 2048 BFOSC/2.16m telescope spectrum from 2019-10-31
lamost.dat 20 3909 LAMOST spectrum from 2014-09-09
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See also:
III/215 : 7th Catalog of Galactic Wolf-Rayet stars (van der Hucht, 2001)
I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/366 : ASAS-SN catalog of variable stars (Jayasinghe+, 2018-2020)
V/146 : LAMOST DR1 catalogs (Luo+, 2015)
J/MNRAS/381/418 : Wolf-Rayet population in NGC 1313 (Hadfield+, 2007)
J/ApJ/764/21 : Stellar evolutionary models with 13-120Msun (Chieffi+, 2013)
Byte-by-byte Description of file: bfosc*.dat
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Bytes Format Units Label Explanations
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1- 9 F9.4 0.1nm lambda [3241.8/8850.6] Wavelength in Angstroms
11- 23 F13.10 10-16W/m2/nm Flux [-2.4/3.4] Flux in 10-14erg/s/cm2/Å
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Byte-by-byte Description of file: lamost.dat
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Bytes Format Units Label Explanations
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1- 9 F9.4 0.1nm lambda [3698.9/9096.7] Wavelength in Angstroms
11- 20 F10.8 10-16W/m2/nm Flux [0.23/6.27]?=0 Flux
in 10-14erg/s/cm2/Å
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-Apr-2022