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J/ApJ/733/123      The Wolf-Rayet content of M33 (NGC 598)     (Neugent+, 2011)

The Wolf-Rayet content of M33. Neugent K.F., Massey P. <Astrophys. J., 733, 123 (2011)> =2011ApJ...733..123N
ADC_Keywords: Stars, Wolf-Rayet ; Equivalent widths ; Photometry, UBV ; Spectral types ; Cross identifications Keywords: galaxies: individual (M33) - galaxies: stellar content - Local Group - stars: evolution - stars: Wolf-Rayet - supergiants Abstract: Wolf-Rayet (WR) stars are evolved massive stars, and the relative number of WC-type and WN-type WRs should vary with metallicity, providing a sensitive test of stellar evolutionary theory. The observed WC/WN ratio is much higher than that predicted by theory in some galaxies but this could be due to observational incompleteness for WN types, which have weaker lines. Previous studies of M33's WR content show a galactocentric gradient in the relative numbers of WCs and WNs, but only small regions have been surveyed with sufficient sensitivity to detect all of the WNs. Here, we present a sensitive survey for WRs covering all of M33, finding 55 new WRs, mostly of WN type. Our spectroscopy also improves the spectral types of many previously known WRs, establishing in one case that the star is actually a background quasar. The total number of spectroscopically confirmed WRs in M33 is 206, a number we argue is complete to ∼5%, with most WRs residing in OB associations, although ∼2% are truly isolated. Description: For the work here on M33 we used the Kitt Peak 4m Mayall telescope and the Mosaic CCD camera to image through a similar set of filters. The data on M33 were obtained on 2000 September 21, 23, and 24 (and allowed to properly age). In order to determine which of our WR candidates were real, we used the 6.5m MMT with the 300 fiber-fed spectrometer Hectospec. The spectra were taken on UT 2010 October 9 and 11 (program NOAO 2010B-0260) and covered the wavelength range 3700-9000Å, with a spectral resolution of 6Å (5 pixels). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 90 6 Non-Of and non-WR stars with emission table3.dat 109 100 New WR and Of-type spectroscopic results table4.dat 58 5 Stars no longer considered WRs table5.dat 102 206 WR stars in M33 table6.dat 31 4 Isolated WR stars in M33 table8.dat 31 6 Additional WR candidates
See also: J/ApJ/705/1364 : MIR catalog of point sources in M33 (Thompson+, 2009) J/AJ/134/2474 : Halpha emission-line stars in dwarfs galaxies (Massey+, 2007) J/AJ/133/2393 : UBVRI in seven Local Group dwarfs galaxies (Massey+, 2007) J/AJ/131/2478 : M31 and M33 UBVRI photometry (Massey+, 2006) J/MNRAS/371/1405 : Variables in M33 (Hartman+, 2006) J/MNRAS/370/1429 : V photometry of bright stars of M33 (Shporer+, 2006) J/AJ/121/870 : BVI photometry of Variables in M33 (Macri+, 2001) J/PAZh/25/18 : Spectroscopy of Halpha blue stars in M 33 (Sholukhova+, 1999) J/ApJ/505/793 : New WR star in M33 (Massey+, 1998) J/ApJ/469/629 : UV-brightest stars of M33 and its nucleus (Massey+ 1996) J/AJ/110/2739 : H-alpha emitting regions in M33 (Calzetti+ 1995) J/ApJS/89/85 : Blue and red supergiants in M33 (Ivanov+ 1993) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 19 A19 --- Star Star designation (JHHMMSS.ss+DDMMSS.s) 21- 25 F5.2 mag Vmag V-band magnitude 27- 30 F4.2 mag B-V (B-V) color index 32- 36 F5.2 mag U-B (U-B) color index 38- 49 A12 --- Type Object type 51- 90 A40 --- Comm Comment
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 19 A19 --- Star Star designation (JHHMMSS.ss+DDMMSS.s) 21- 29 A9 --- SpT MK spectral type 31- 39 A9 --- SpTp Previous MK spectral type 41- 53 A13 --- ID Previous identification 55 I1 --- r_SpTp ? Reference (G1)(1) 57- 60 F4.1 [0.1nm] logW4 ? HeIIlambda4686 or CIIIlambda4650 equivalent width (2) 62- 63 I2 km/s FWHM4 ? Full width at half maximum (2) 65- 67 F3.1 [0.1nm] logW5 ? CIVlambda5806 equivalent width (3) 69- 71 I3 km/s FWHM5 ? CIVlambda5806 FWHM (3) 73-109 A37 --- Comm Comment
Note (1): Reference for old spectral types are from Massey & Johnson 1998, Cat. J/ApJ/505/793, unless reference given (see note G1). Note (2): We measured the EWs and full widths at half-maxima (FWHMs) of the "discovery" lines, HeIIλ4686 for the WNs, and the CIIIλ4650 and HeIIλ4686 blend in WCs. For WCs, the very strong CIIIλ4650 feature is blended with (and dominates over) HeIIλ4686. Note (3): We also measure the EWs and FWHMs of CIIIλ4650, and CIV5801, CIV5812 feature (hereafter referred to as CIVλ5806) if present.
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 19 A19 --- Star Star designation (JHHMMSS.ss+DDMMSS.s) 21- 24 A4 --- SpTo Old MK spectral type 26 I1 --- r_SpTo Old spectral type reference (G1) 28- 36 A9 --- SpT New type 38- 39 I2 --- r_SpT New type reference (G1) 41- 58 A18 --- oID Other identification(s)
Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 19 A19 --- Star Star designation (JHHMMSS.ss+DDMMSS.s) 21- 24 F4.2 --- rho Normalized distance from the center within the plane of M33 (1) 26- 35 A10 --- SpT MK spectral type 36 A1 --- f_SpT [i] Variable spectrum for J013332.64+304127.2 (2) 38 I1 --- r_SpT Reference for spectral type (G1) 40- 44 F5.2 mag Vmag V-band magnitude from Massey et al. (2006, Cat. J/AJ/131/2478) 46- 50 F5.2 mag m4750 4750AA AB magnitude (3) 52- 55 F4.1 mag VMag Absolute visual magnitude (4) 57- 60 F4.1 mag M4750 4750AA absolute magnitude (4) 62- 64 A3 --- OB OB association (5) 66 A1 --- f_OB [fo] Field star, or Outside association (6) 68- 72 A5 --- [MJ98] Massey & Johnson (1998, Cat. J/ApJ/505/793) WR designation (<[MJ98] WR NNNA> in Simbad) 74- 86 A13 --- ID Other identification (7) 88-102 A15 --- Comm Comment
Note (1): Distance from the center within the plane of M33, normalized to the D25 isophotoal radius of 30.8' assuming RAJ2000=01:33:50.89, DECJ2000=30:39:36.8, an inclination of 56°, and a position angle of the major axis of 23°, following Kwitter & Aller (1981MNRAS.195..939K) and Zaritsky et al. (1989AJ.....97...97Z). Note (2): i = J013332.64+304127.2 was shown to be a late-type WN star by Massey & Conti (1983ApJ...273..576M; [MC83] 28), and later identified by HeIIλ4686 imaging by Armandroff & Massey (1985ApJ...291..685A), where it is listed as AM 2 ([AM85] M 33 2). However, Massey et al. (2006, Cat. J/AJ/131/2478) found that the spectrum has since changed dramatically, resembling a hot luminous blue variable (LBV). Note (3): AB magnitude through continuum ("CT") filter centered at 4750Å and calibrated using the values from Massey & Johnson (1998, Cat. J/ApJ/505/79). Note (4): Absolute magnitudes computed assuming a true distance modulus of 24.60 (830Mpc) and adopting an average reddening of E(B-V)=0.12 based on Massey et al. (2007, Cat. J/AJ/133/2393). Adopting RV=3.1 leads to an AV=0.37mag and Am4750=0.45mag. Note (5): OB association as defined by Humphreys & Sandage (1980ApJS...44..319H; <[HS80] NNNa> in Simbad). Note (6): Flag as follows: f = field star, not in a cataloged OB association. o = the star is just outside the boundaries of the association Note (7): IDs are from Massey & Johnson (1998, Cat. J/ApJ/505/793, <[MJ98] ANN> in Simbad) and references therein; or N592- and N604- = other than the HII regions designations by Drissen et al. (2008MNRAS.389.1033D; <DMS NGC NNN NN> in Simbad) K10 = Kehrig et al. (2011A&A...526A.128K) MC = Massey & Conti (1983ApJ...273..576M, <[MC83] NN> in Simbad) UIT = Massey et al. 1996, Cat. J/ApJ/469/629, <[MBH96] NNN> in Simbad OB = Massey et al. 1995AJ....110.2715M, <[MAP95] M 33 OBNN NN> in Simbad MCA = Massey et al. 1987PASP...99..816M AM = Armandoff & Massey 1985ApJ...291..685A; <[AM85] M 33 NN> in Simbad
Byte-by-byte Description of file: table6.dat
Bytes Format Units Label Explanations
1- 19 A19 --- Star Star designation (JHHMMSS.ss+DDMMSS.s) 21- 24 F4.2 --- rho Distance from the center within the plane of M33 26- 31 A6 --- SpT MK spectral type
Byte-by-byte Description of file: table8.dat
Bytes Format Units Label Explanations
1- 19 A19 --- Star Star designation (JHHMMSS.ss+DDMMSS.s) 21- 25 F5.2 mag Vmag V-band magnitude 27- 31 F5.2 mag m4650 4650Å magnitude
Global notes: Note (G1): Reference as follows: 1 = This work; 2 = Massey & Johnson 1998, Cat. J/ApJ/505/793; 3 = Kehrig et al. 2011A&A...526A.128K; 4 = Massey et al. 2007, Cat. J/AJ/134/2474; 5 = Drissen et al. 2008MNRAS.389.1033D; 6 = Abbott et al. 2004MNRAS.350..552A 7 = Massey & Conti 1983ApJ...273..576M; 8 = Crowther et al. 1997A&A...318..543C; 9 = Massey et al. 1996, Cat. J/ApJ/469/629; 10 = Abbott et al. 2004MNRAS.350..552A
History: From electronic version of the journal
(End) Emmanuelle Perret [CDS] 15-Nov-2012
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