J/A+A/626/A50 Massive stars in NGC 346 (Dufton+, 2019)
A census of massive stars in NGC 346.
Stellar parameters and rotational velocities.
Dufton P.L., Evans C.J., Hunter I., Lennon D.J., Schneider F.R.N.
<Astron. Astrophys., 626, A50 (2019)>
=2019A&A...626A..50D 2019A&A...626A..50D (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Associations, stellar ;
Rotational velocities ; MK spectral classification
Keywords: stars: early-type - stars: atmospheres - stars: rotation -
stars: evolution - Magellanic Clouds -
open clusters and associations: individual: NGC 346
Abstract:
Spectroscopy for 247 stars towards the young cluster NGC 346 in the
Small Magellanic Cloud has been combined with that for 116 targets
from the VLT-FLAMES Survey of Massive Stars. Spectral classification
yields a sample of 47 O-type and 287 B-type spectra, while
radial-velocity variations and/or spectral multiplicity have been used
to identify 45 candidate single-lined (SB1) systems, 17 double-lined
(SB2) systems, and one triple-lined (SB3) system. Atmospheric
parameters (Teff and log g) and projected rotational velocities
(vesini) have been estimated usingTLUSTY model atmospheres;
independent estimates of vesini were also obtained using a Fourier
Transform method. Luminosities have been inferred from stellar
apparent magnitudes and used in conjunction with the Teff and
vesini estimates to constrain stellar masses and ages using
theBONNSAI package. We find that targets towards the inner region of
NGC 346 have higher median masses and projected rotational velocities,
together with smaller median ages than the rest of the sample. There
appears to be a population of very young targets with ages of less
than 2Myr, which have presumably all formed within the cluster. The
more massive targets are found to have lower projected rotational
velocities consistent with previous studies. No significant evidence
is found for differences with metallicity in the stellar rotational
velocities of early-type stars, although the targets in the Small
Magellanic Cloud may rotate faster than those in young Galactic
clusters. The rotational velocity distribution for single
non-supergiant B-type stars is inferred and implies that a significant
number have low rotational velocity (~=10% with ve<40km/s), together
with a peak in the probability distribution at ve~=300km/s. Larger
projected rotational velocity estimates have been found for our
Be-type sample and imply that most have rotational velocities between
200-450km/s.
Description:
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 115 247 Observational parameters of target stars
notes.dat 80 28 Individual notes
tablea2.dat 76 358 Atmospheric parameters (Teff, log g) and projected
rotational velocities (vesini), luminosities,
current masses and ages for the NGC 346 sample
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See also:
J/PASP/98/1133 : The open cluster NGC 346 (Niemela+, 1986)
J/AJ/98/1305 : Stellar content of NGC 346 (Massey+, 1989)
J/A+A/456/623 : VLT-FLAMES survey of massive stars (Evans+, 2006)
J/ApJS/166/549 : HST/ACS observations of NGC 346 (Gouliermis+, 2006)
J/AJ/133/44 : NGC 346 HST VI photometry (Sabbi+, 2007)
J/ApJ/672/914 : HST photometry in NGC 346 (Hennekemper+, 2008)
J/A+A/515/A56 : NGC 346/N66 JHKs photometry (Gouliermis+, 2010)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Star [1001/1247] Star number
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 16 F5.2 s RAs Right ascension (J2000)
18 A1 --- DE- Declination sign (J2000)
19- 20 I2 deg DEd Declination (J2000)
22- 23 I2 arcmin DEm Declination (J2000)
25- 28 F4.1 arcsec DEs Declination (J2000)
30- 33 F4.2 arcmin rd Radial distance (1)
35- 39 F5.2 mag Vmag V magnitude
41- 45 F5.2 mag B-V B-V colour index
47- 61 A15 --- SpType Spectral Type
63-115 A53 --- Com Comments (2)
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Note (1): Additionally eclipsing binaries (EB) from the OGLE project
(Udalski et al., 1998, Cat. J/AcA/48/563) have been identified.
Radial distances from #1001 (rd, in arcmin) are given for each star
(1' corresponds to a physical distance of ∼17.5pc).
Note (2): Cross-references to previous identifications are given as:
Sanduleak (1968AJ.....73..246S 1968AJ.....73..246S, Sk),
Azzopardi & Vigneau (1975A&AS...19..271A 1975A&AS...19..271A, 1982, AzV),
Walborn & Blades (1986ApJ...304L..17W 1986ApJ...304L..17W, WB),
Niemela et al. (1986, Cat. %q Niemela et al. 1986 (J/PASP/98/1133NMC),
Massey et al. (1989, Cat. J/AJ/98/1305, MPG),
Meyssonnier & Azzopardi (1993, Cat. J/A+AS/102/451, MA93),
Keller et al. (1999, Cat. J/A+AS/134/489, KWB),
Evans et al. (2004, Cat. J/MNRAS/353/6012, dFS).
(+) indicates a note in notes.dat files.
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Star Star number
6- 80 A75 --- Note Note
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Star [1/1247] Star number
5 A1 --- n_Star [*] Note on Star (1)
7- 22 A16 --- SpType Spectral Type
24- 28 I5 K Teff ?=- Effective temperature
30- 32 A3 --- Method Method used to estimate the
effective temperature (2)
34- 37 F4.2 [cm/s2] logg ?=- Surface gravity
39- 40 A2 --- l_vesiniPF [≤ ] Limit flag on vesiniPF
42- 44 I3 km/s vesiniPF ? Projected rotational velocity estimated
with the profile fitting (PF)
46- 47 A2 --- l_vesiniFT [≤ ] Limit flag on vesiniFT
48- 50 I3 km/s vesiniFT ?=- Projected rotational velocity estimated
with the Fourier transform (FT)
52- 55 F4.2 arcmin r Radius
57- 60 F4.2 [Lsun] logL ?=- Luminosity
62- 65 F4.1 Msun Mass ?=- Mass
67- 71 F5.1 Myr Age ?=- Age
73- 76 A4 --- Com Comment (3)
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Note (1): Targets marked with an asterisk appear to be overluminous for an
assumed luminosity class V and their estimates should be treated with caution.
Note (2): Method used to estimate the effective temperature as follows:
H08 = taken from Hunter et al. (2008, Cat. J/A+A/479/541)
M06 = taken from Mokiem et al. (2006A&A...456.1131M 2006A&A...456.1131M)
A = adopted from effective temperature scales of Trundle et al.
(2007, Cat. J/A+A/471/625)
I = interpolated from these temperature scales
E = extrapolated from these temperature scales
M = luminosity class V assumed
Si = silicon ionization balance
He = HeI line at 4026Å
He+ = HeII lines at 4541 and 4686Å
L = literature
Note (3): SB1 indicates that significant radial velocity variables were detected
while the double-lined spectroscopic binaries are designated as SB2 (and one
tripled-lined system as SB3).
Many of the Be-type stars from the FSMS were classified by (Evans et al.,
2006, Cat. J/A+A/456/623) as "(Be-Fe)" to indicate Fe II emission.
This spectral qualifier has not been used further elsewhere (including for the
Survey spectra here) but for completeness cf. the published types,
these suffixes are included below.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 08-Aug-2019