J/ApJ/868/57 Spectroscopic HR diagram of OB stars in the SMC (Castro+, 2018)
The spectroscopic Hertzsprung-Russell diagram of hot massive stars in the Small
Magellanic Cloud.
Castro N., Oey M.S., Fossati L., Langer N.
<Astrophys. J., 868, 57 (2018)>
=2018ApJ...868...57C 2018ApJ...868...57C
ADC_Keywords: Stars, OB; Magellanic Clouds; Effective temperatures;
Stars, masses
Keywords: galaxies: stellar content; Magellanic Clouds; stars: early-type;
stars : emission-line, Be; stars: fundamental parameters
Abstract:
We present a comprehensive stellar atmosphere analysis of 329 O- and
B-type stars in the Small Magellanic Cloud (SMC) from the RIOTS4
survey. Using spectroscopically derived effective temperature Teff and
surface gravities, we find that classical Be stars appear misplaced to
low Teff and high luminosity in the spectroscopic Hertzsprung-Russell
diagram (sHRD). Together with the most luminous stars in our sample,
the stellar masses derived from the sHRD for these objects are
systematically larger than those obtained from the conventional
Hertzsprung-Russell diagram. This suggests that the well-known,
spectroscopic mass-discrepancy problem may be linked to the fact that
both groups of stars have outer envelopes that are nearly
gravitationally unbound. The non-emission-line stars in our sample
mainly appear on the main sequence, allowing a first estimate of the
terminal-age main sequence (TAMS) in the SMC, which matches the
predicted TAMS between 12 and 40M☉ at SMC metallicity. We
further find a large underabundance of stars above ∼25M☉ near
the zero-age main sequence, reminiscent of such earlier findings in
the Milky Way and Large Magellanic Cloud.
Description:
The catalogue contains parameters for 329 O and B-type stars in the
SMC. The selected sample comprises of 223 stars previously classified
by Lamb+ (2016, J/ApJ/817/113 ; Runaways and Isolated O-Type Star
Spectroscopic Survey of the Small Magellanic Cloud (RIOTS4)) and 106
stars newly observed in the SMC Wing, which were selected from the
catalog of Evans+ (2004, J/MNRAS/353/601 ; 2dF of the SMC) (see also
Bonanos+ 2010, J/AJ/140/416).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 74 329 OB sample in the SMC analyzed in this work
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See also:
II/236 : UBVR CCD survey of the Magellanic clouds (Massey+, 2002)
J/MNRAS/353/601 : 2dF survey of the Small Magellanic Cloud (Evans+, 2004)
J/AJ/127/1632 : UBVR(UIT) photometry of O and OB stars in SMC (Oey+, 2004)
J/ApJ/659/1198 : ARAUCARIA project: NGC 3109 blue supergiants (Evans+, 2007)
J/A+A/471/625 : VLT-FLAMES survey of massive stars (Trundle+, 2007)
J/AJ/140/416 : IR photometry of massive stars in the SMC (Bonanos+, 2010)
J/A+A/530/A115 : Rotating massive MS stars evolutionary models (Brott+, 2011)
J/A+A/532/A147 : HST photometry in extragalactic star clusters (Larsen+, 2011)
J/A+A/537/A146 : Stellar models with rotation. Z=0.014 (Ekstrom+, 2012)
J/A+A/539/A143 : Nearby B-stars stellar param. and abundances (Nieva+, 2012)
J/other/Sci/337.444 : RV curves of Galactic massive O stars (Sana+, 2012)
J/A+A/558/A103 : Stellar models with rotation. Z=0.002 (Georgy+, 2013)
J/MNRAS/442/1680 : Red giants in SMC. Abundances (Dobbie+, 2014)
J/ApJ/780/59 : The Araucaria project: EBs in SMC (Graczyk+, 2014)
J/A+A/591/A11 : SMC BV photometry of 9 star cluster fields (Dias+, 2016)
J/ApJ/817/113 : RIOTS4: spec. survey of SMC field OB stars (Lamb+, 2016)
J/ApJ/816/49 : Spitzer/IRAC observations of SMC Cepheids (Scowcroft+, 2016)
J/A+A/600/A81 : VLTS. 30Dor O giants & supergiants (Ramirez-Agudelo+, 2017)
J/A+A/601/A79 : VLTS. O dwarf in 30 Dor (Sabin-Sanjulian+, 2017)
J/A+A/597/A22 : Massive O- and B-type stars velocities (Simon-Diaz+, 2017)
J/A+A/613/A65 : Spectroscopic parameters of O-type stars (Holgado+, 2018)
J/ApJ/867/L8 : Gaia kinematic data of OB stars in SMC (Oey+, 2018)
J/other/Sci/359.69 : Massive stars in 30 Dor (Schneider+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ID Massey 2002, II/236 identifier;
<[M2002] SMC NNNNN> in Simbad
7- 8 I2 h RAh [0/1] Hour of Right Ascension (J2000)
10- 11 I2 min RAm Minute of Right Ascension (J2000)
13- 17 F5.2 s RAs Second of Right Ascension (J2000)
19 A1 --- DE- [-] Sign of the Declination (J2000)
20- 21 I2 deg DEd [71/73] Degree of Declination (J2000)
23- 24 I2 arcmin DEm Arcminute of Declination (J2000)
26- 29 F4.1 arcsec DEs Arcsecond of Declination (J2000)
31- 34 F4.2 [K] logTeff [4/4.7] log effective temperature
36- 39 F4.2 [K] e_logTeff [0/0.2] Uncertainty in logTeff
41- 44 F4.2 [Lsun] logLs [2.7/4.6] log spectroscopic luminosity (1)
46- 50 F5.2 [Lsun] e_logLs [-0/0.7] Uncertainty in logLs
52- 55 F4.2 [Lsun] logL [0/6] log luminosity
57- 60 F4.2 [Lsun] e_logL [0/0.4] Uncertainty in logL
62- 65 F4.2 [Msun] logMsHRD [0.7/2]? log estimated mass in the
spectroscopic Hertzsprung-Russell
diagram (sHRD)(1)
67- 70 F4.2 [Msun] logMHRD [0.7/1.7]? log estimated mass in the
Hertzsprung-Russell diagram (HRD)
72 A1 --- Em [e] Balmer line emission flag (2)
74 A1 --- Met [m] Metals flag (2)
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Note (1): The spectroscopic luminosity and the spectroscopic
Hertzsprung-Russell diagram (sHRD) are defined in Langer & Kudritzki
(2014A&A...564...52L 2014A&A...564...52L). See also Castro et al. (2014A&A...570...13C 2014A&A...570...13C).
Note (2): Flag as follows:
e = a star with emissions in any of the Balmer lines.
m = a star with Si III 4552A equivalent width larger than 0.15Å.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 22-Oct-2019