J/MNRAS/381/418 Wolf-Rayet population in NGC 1313 (Hadfield+, 2007)
A survey of the Wolf-Rayet population of the barred, spiral galaxy NGC 1313.
Hadfield L.J., Crowther P.A.
<Mon. Not. R. Astron. Soc., 381, 418-432 (2007)>
=2007MNRAS.381..418H 2007MNRAS.381..418H
ADC_Keywords: Galaxies, nearby ; Stars, Wolf-Rayet ; Photometry ; Spectroscopy
Keywords: stars: Wolf-Rayet - galaxies: individual: NGC 1313
Abstract:
We present a VLT/FORS1 survey of Wolf-Rayet (WR) stars in the spiral
galaxy NGC 1313. In total, 94 WR candidate sources have been
identified from narrow-band imaging. Of these, 82 have been
spectroscopically observed, for which WR emission features are
confirmed in 70 cases, one of which also exhibits strong nebular
HeIIλ4686 emission. We also detect strong nebular
HeIIλ4686 emission within two other regions of NGC 1313, one of
which is a possible supernova remnant. Nebular properties confirm that
NGC 1313 has a metal content log(O/H)+12=8.23±0.06, in good
agreement with previous studies. From continuum-subtracted Hα
images we infer a global star formation rate of 0.6M_☉/yr. Using
template LMC WR stars, spectroscopy reveals that NGC 1313 hosts a
minimum of 84 WR stars. Our census comprises 51 WN stars, including a
rare WN/C transition star plus 32 WC stars. In addition, we identify
one WO star which represents the first such case identified beyond the
Local Group. The bright giant HII region PES 1, comparable in Hα
luminosity to NGC 595 in M 33, is found to host a minimum of 17 WR
stars. The remaining photometric candidates generally display
photometric properties consistent with WN stars, such that we
expect a global WR population of ∼115 stars with N(WR)/N(O)∼0.01
and N(WC)/N(WN)∼0.4.
Description:
NGC 1313 has been observed with the ESO Very Large Telescope UT2
(Kueyen) and Focal Reduced/Low-dispersion Spectrograph #1 (FORS1).
The data were obtained using the standard resolution collimator which
covers a 6.8x6.8-arcmin2 field of view, with a plate scale of
0.2arcsec/pixel. Photometric observations of NGC 1313 were obtained
on 2004 October 12, with spectroscopic data following in 2004 November
and 2005 November-December.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea2.dat 120 94 *Catalogue of candidate HeII emission regions
within NGC 1313
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Note on tablea2.dat: We present line properties and spectral types for
those regions which have been classified via follow-up spectroscopy.
Sources believed to host multiple WRs based on the observed line flux
or appearance on the continuum-subtracted λ4684 image have been
identified.
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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- 2 I2 --- [HC2007] [1/94] Sequential number
4- 5 I2 h RAh Right ascension (J2000)
7- 8 I2 min RAm Right ascension (J2000)
10- 13 F4.1 s RAs Right ascension (J2000)
15 A1 --- DE- Declination sign (J2000)
16- 17 I2 deg DEd Declination (J2000)
19- 20 I2 arcmin DEm Declination (J2000)
22- 25 F4.1 arcsec DEs Declination (J2000)
27- 30 F4.2 --- R/R0 Deprojected distance (1)
32- 33 I2 --- [WR97] ? Walsh & Roy (1997MNRAS.288..726W 1997MNRAS.288..726W)
HII association number
34 A1 --- n_[WR97] [)] ) for candidates which reside close to
[WR97] and [PES80] regions
35- 36 I2 --- [PES80] ? Pagel et al. (1980MNRAS.193..219P 1980MNRAS.193..219P)
HII association number
38 A1 --- l_Bmag Limit flag on Bmag
39- 42 F4.1 mag Bmag ?=- B magnitude
43 A1 --- n_Bmag [E] E for extended
46 A1 --- l_m4684 Limit flag on m4684
47- 50 F4.1 mag m4684 ?=- Magnitude at FORS1 narrow-band
λ4684 filter
51 A1 --- u_m4684 Uncertainty flag on m4684
52 A1 --- n_m4684 [E] E for extended
53 A1 --- l_Dmag Limit flag on Dmag
54- 57 F4.1 mag Dmag ?=- Magnitude difference, m4684-Bmag
58 A1 --- n_Dmag [E] E for extended
59 A1 --- f_F(4650+86) [*] * for No data available
60- 66 E7.2 mW/m2 F(4650+86) ? Dereddened line fluxes at 4650Å
and 4686Å (2)
67 A1 --- n_F(4650+86) [n] n for No blue data
68- 74 E7.2 solLum L(4650+86) ? Luminosity of 4650Å and 4686Å lines
76- 82 E7.2 mW/m2 F(5808) ? Dereddened line flux at 5808Å (2)
84- 90 E7.2 solLum L(5808) ? Luminosity of 5808Å line
92-105 A14 --- SpType Spectral type
107-120 A14 --- Rem Remarks (3)
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Note (1): Deprojected distances are expressed as a fraction of the
Holmberg radius R0=4.6arcmin=5.5kpc.
Note (2): Dereddened line fluxes have been derived assuming E(B-V)=0.29mag.
Note (3): Regions which are awaiting follow-up spectroscopy have been
labelled WN? or NON-WR? depending on their photometric excess and
appearance on the continuum-subtracted 4684 image. The number of
WR stars in each source is estimated using the line luminosity
calibrations of Crowther & Hadfield (2006A&A...449..711C 2006A&A...449..711C) and a
distance modulus of 28.08mag (Mendez et al. 2002AJ....124..213M 2002AJ....124..213M)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 11-Feb-2008