J/A+A/439/265 Wolf-Rayet population in M83 (Hadfield+, 2005)
A spectroscopic search for the non-nuclear Wolf-Rayet population of the
metal-rich spiral galaxy M83.
Hadfield L.J., Crowther P.A., Schild H., Schmutz W.
<Astron. Astrophys., 439, 265-277 (2005)>
=2005A&A...439..265H 2005A&A...439..265H
ADC_Keywords: Galaxies, spectra ; Equivalent widths ; Stars, variable
Keywords: galaxies: individual: M 83 - stars: Wolf-Rayet
Abstract:
We present a catalogue of non-nuclear regions containing Wolf-Rayet
stars in the metal-rich spiral galaxy M 83 (NGC 5236). From a total
of 283 candidate regions identified using He II λ4686 imaging
with VLT-FORS2, Multi Object Spectroscopy of 198 regions was carried
out, confirming 132 WR sources. From this sub-sample, an exceptional
content of ∼1035±300 WR stars is inferred, with N(WC)/N(WN) ∼ 1.2,
continuing the trend to larger values at higher metallicity amongst
Local Group galaxies, and greatly exceeding current evolutionary
predictions at high metallicity.
Description:
We have observed M83 with the ESO Very Large Telescope UT4 (Yepun)
and Focal Reduced/Low Dispersion Spectrograph #2 (FORS2). The detector
consists of a mosaic of two 2048x1024 MIT/LL CCDs which in conjunction
with the standard collimator provides a field-of-view 6.8'x6.8' and an
image scale of 0.126"/pixel. Photometric observations of M83 were
made between May-June 2002 with follow-up spectroscopic data being
acquired during April-June 2003.
FORS2 was used on 2 June 2002 to obtain narrow-band images with
central wavelengths 4684Å, 4781Å and band widths of 66Å and
68Å respectively. These were obtained consecutively for each Field
in seeing conditions between 0.6-0.8" with individual exposures of
1800s. The λ4684 filter is coincident with the strong WR
emission features which incorporates the N III (λ4640Å),
C III (λ4650Å) and He II (λ4686Å) emission lines,
whereas the latter samples a wavelength region relatively free from
emission, providing a measure of the continuum level.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 33 18 FORS2 Multi Object Spectroscopy (MOS)
observing log for M83.
tablea1.dat 202 132 Catalogue of sources with confirmed WR
spectroscopic signatures in M83.
tablea2.dat 48 89 Catalogue of sources with candidate WR signatures
in M83, either from narrow-band imaging or for
which MOS spectroscopy was ambiguous.
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 "YYYY-MM-DD" Date Observation date
12- 17 A6 --- MOD MOD mask
19- 24 A6 s Exp Exposure time(s)
26- 28 F3.1 arcsec Seeing1 DIMM seeing
29 A1 --- --- [,]
31- 33 F3.1 arcsec Seeing2 ? DIMM seeing
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [HCS2005] Sequential number of the source
4 A1 --- n_[HCS2005] [a] Note on [HCS2005] (1)
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 ---- rho/rho0 De-projected distances are expressed as a
fraction of the Holmberg radius
rho0=7.3'=9.56kpc
35 A1 --- l_m4686 Limit flag on m4686
36- 39 F4.1 mag m4686 ? He II (4686Å) band magnitude
40 A1 --- n_m4686 [)c] Note on m4686 (G2)
43- 46 F4.1 mag Dm ? Magnitude difference, m4684-m4781 (G3)
47 A1 --- n_Dm [)] ): spectroscopic photometry
49- 52 F4.2 mag E(B-V) ? Reddening
53 A1 --- n_E(B-V) [b] b: average E(B-V) value has been assumed
54 A1 --- l_BMAG Limit flag on BMAG
55- 59 F5.1 mag BMAG ? Absolute B magnitude
60 A1 --- n_BMAG [)] ): spectroscopic photometry
62- 63 I2 --- [DPD83] ? HII region in de Vaucouleurs et al.,
1983ApJS...53...17D 1983ApJS...53...17D, [DPD83] NN, number
65 A1 --- l_EWC/He Limit flag on EWCIII/HeII
66- 69 I4 0.1nm EWC/He ? Equivalent width of CIII(4650)/HeII(4686)
71- 73 I3 0.1nm FWHMC/He ? FWHM of CIII/HeII
74- 75 A2 --- n_FWHMC/He [ND] ND for No data
77- 83 E7.2 mW/m2 FC/He ? Observed line flux of CIII/HeII
85- 86 A2 --- n_EWC/He [ND] ND for No data
89 A1 --- l_EWCIII Limit flag on EWCIII
90- 92 I3 0.1nm EWCIII ? Equivalent width of CIII(5696)
94 A1 --- l_FWHMCIII Limit flag on FWHMCIII
95- 96 I2 0.1nm FWHMCIII ? FWHM of CIII
98-104 E7.2 mW/m2 FCIII ? Observed line flux of CIII
106 A1 --- l_EWCIV Limit flag on CIV
107-110 I4 0.1nm EWCIV ? Equivalent width of CIV(5808)
112-114 I3 0.1nm FWHMCIV ? FWHM of CIV
116-122 E7.2 mW/m2 FCIV ? Observed line flux of CIV
124-125 I2 --- WN2-5 ? Number of WN2-5 type stars in the source (4)
127-128 I2 --- WN6-10 ? Number of WN6-10 type stars in the source (4)
130 I1 --- WC4-6 ? Number of WC4-6 type stars in the source (4)
132-133 I2 --- WC7 ? Number of WC7 type stars in the source (4)
135-137 I3 --- WC8-9 ? Number of WC8-9 type stars in the source (4)
139-146 A8 ---- MOS Multi Object Spectroscopy (MOS) mask used
148-150 F3.1 mag e_m4686 ? rms uncertainty on m4686
152-154 F3.1 mag e_Dm ? rms uncertainty on Dm
156-159 F4.2 mag e_E(B-V) ? rms uncertainty on E(B-V)
161-163 F3.1 mag e_BMAG ? rms uncertainty on BMAG
165-171 E7.2 0.1nm e_FWHMC/He ? rms uncertainty on FWHMC/He
173-179 E7.2 0.1nm e_FWHMCIII ? rms uncertainty on FWHMCIII
181-187 E7.2 0.1nm e_FWHMCIV ? rms uncertainty on FWHMCIV
189-190 I2 --- e_WN2-5 ? rms uncertainty on WN2-5
192-193 I2 --- e_WN6-10 ? rms uncertainty on WN6-10
195 I1 --- e_WC4-6 ? rms uncertainty on WC4-6
197-198 I2 --- e_WC7 ? rms uncertainty on WC7
200-202 I3 --- e_WC8-9 ? rms uncertainty on WC8-9
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Note (1): 'a' f He II PSF or spectroscopic photometry was unavailable
and the average slit loss correction factor has been assumed.
Note (4): The number of, and error in, WR stars in each source are
estimated from the line luminosities indicated in Sect. 3.2 and
a distance of 4.5±0.3Mpc
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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- 3 I3 --- [HCS2005] Sequential number of the source
4 A1 --- n_[HCS2005] [pl] Note on [HCS2005] (1)
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 ---- rho/rho0 De-projected distances are expressed as a
fraction of the Holmberg radius
rho0=7.3'=9.56kpc
35 A1 --- l_m4686 Limit flag on m4686
36- 39 F4.1 mag m4686 ?=- He II (4686Å) band magnitude
40 A1 --- n_m4686 [c] Note on m4686 (G2)
42- 45 F4.1 mag Dm ?=- Magnitude difference, m4684-m4781 (G3)
47- 48 I2 --- [DPD83] ? HII region in de Vaucouleurs et al.,
1983ApJS...53...17D 1983ApJS...53...17D, [DPD83] NN, number
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Note (1): Note on [HCS2005] as follows:
p = Insufficient S/N for classification
l = insufficient spectral coverage for WN identification
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Global notes:
Note (G2): Notes as follows:
c = photometry corresponds to a lower limit as the region is extended
) = spectroscopic photometry
Note (G3): Dm corresponds to the HeII/CIII excess emission (at 4684Å)
relative to the continuum (4781Å),
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 23-Mar-2006