2009ApJ...704.1120U

Query : 2009ApJ...704.1120U

2009ApJ...704.1120U - Astrophys. J., 704, 1120-1134 (2009/October-3)

A new distance to M33 using blue supergiants and the FGLR method.

U V., URBANEJA M.A., KUDRITZKI R.-P., JACOBS B.A., BRESOLIN F. and PRZYBILLA N.

Abstract (from CDS):

The quantitative spectral analysis of medium resolution optical spectra of A and B supergiants obtained with DEIMOS and ESI at the Keck Telescopes is used to determine a distance modulus of 24.93±0.11 mag (968±50 kpc) for the Triangulum Galaxy M33. The analysis yields stellar effective temperatures, gravities, interstellar reddening, and extinction, the combination of which provides a distance estimate via the flux-weighted gravity-luminosity relationship (FGLR). This result is based on an FGLR calibration that is continually being polished. An average reddening of ∼ 0.08 mag is found, with a large variation ranging from 0.01 to 0.16 mag, however, demonstrating the importance of accurate individual reddening measurements for stellar distance indicators in galaxies with evident signatures of interstellar absorption. The large-distance modulus found is in good agreement with recent work on eclipsing binaries, planetary nebulae, long-period variables, RR Lyrae stars, and also with Hubble Space Telescope (HST) observations of Cepheids, if reasonable reddening assumptions are made for the Cepheids. Since distances based on the tip of the red giant branch (TRGB) method found in the literature give conflicting results, we have used HST Advanced Camera for Surveys V- and I-band images of outer regions of M33 to determine a TRGB distance of 24.84 ±0.10 mag, in basic agreement with the FGLR result. We have also determined stellar metallicities and discussed the metallicity gradient in the disk of M33. We find metallicity of Z☉ at the center and 0.3 Z☉ in the outskirts at a distance of one isophotal radius. The average logarithmic metallicity gradient is -0.07±0.01 dex/kpc. However, there is a large scatter around this average value, very similar to what has been found for the H II regions in M33.

Abstract Copyright: ∼

Journal keyword(s): galaxies: distances and redshifts - galaxies: individual: M33 - stars: abundances - stars: early-type - supergiants

CDS comments: Tables 1-2: Numbering NN (col. 1) not used in Simbad.

Simbad objects: 35

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Number of rows : 35
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 12317 1
2 NGC 300 GiG 00 54 53.4465638304 -37 41 03.168402396 8.83 8.69 8.13 7.46   ~ 1614 2
3 LGGS J013229.61+303513.3 sg* 01 32 29.5573998678 +30 35 13.074116544           A0I 1 0
4 [HS80] 117A sg* 01 33 00.1866085080 +30 23 23.471056572 15.964 16.582 16.440 16.373 16.301 A0I 13 0
5 [HS80] B38 s*b 01 33 00.8233999800 +30 35 04.723949616 16.111 17.204 17.322 17.362 17.378 B1I 18 0
6 [HS80] B84 s*b 01 33 15.5842435968 +30 29 49.093096884 16.580 17.181 17.120 17.061 17.013 B9I 7 0
7 LGGS J013327.35+310056.4 s*b 01 33 27.3113658096 +31 00 56.379298572   17.78 17.88     B0.7I 6 0
8 [HS80] B133 s*b 01 33 28.9563601920 +30 47 44.000454012 15.715 16.677 16.742 16.737 16.756 B2.5Ia 34 0
9 [MBH96] 122 s*b 01 33 33.6801730416 +30 47 19.941877176 16.628 17.691 17.754 17.758 17.764 B0.5I 6 0
10 [HS80] B157 s*b 01 33 35.7296159520 +31 00 46.882990260 16.723 17.754 17.898 17.914 17.976 B0.5I 12 0
11 [HS80] B182 sg* 01 33 37.0559278800 +30 35 21.395480784 17.7 18.00 17.94 17.9 17.8 A2 8 0
12 LGGS J013339.08+302010.7 s*b 01 33 39.0569491188 +30 20 10.572006240 16.25 17.13 17.051 17.21 17.24 B3I 4 1
13 IFM-B 755 sg* 01 33 40.2564137236 +30 21 43.966388504   17.79 17.84     A0I 7 0
14 LAMOST J013340.47+303503.3 s*b 01 33 40.4386563904 +30 35 03.101093416   18.022 17.997     B9I 3 0
15 IFM-B 767 s*b 01 33 40.5021211765 +30 31 58.595626820 17.212 18.008 18.047 18.043 18.011 B3I 8 0
16 LAMOST J013340.84+303822.5 sg* 01 33 40.8038580080 +30 38 22.491954452   18.407 18.235     A2I 3 0
17 [HS80] 110A s*b 01 33 41.2375209576 +30 22 37.077649428 15.181 16.236 16.285 16.279 16.321 B1Ia 23 0
18 LAMOST J013341.36+303629.6 sg* 01 33 41.3259814011 +30 36 29.392169440   18.019 17.913     A2I 2 0
19 [HS80] B287 s*b 01 33 42.0212826840 +30 21 42.110672976 16.759 17.810 17.989 18.052 18.170 B0I 12 0
20 [HS80] B241 sg* 01 33 43.2114426899 +30 31 53.618556816   17.267 17.221     A0I 5 0
21 LGGS J013344.26+303148.0 s*b 01 33 44.2084607847 +30 31 47.876638872 16.162 17.229 17.315 17.334 17.352 B1Ia+ 7 0
22 LAMOST J013344.27+304247.2 s*b 01 33 44.2335150259 +30 42 47.097721336   18.22 18.209     B3I 4 0
23 [MC83] 45 WR* 01 33 44.3906340072 +30 38 43.871534232 17.541 17.467 21.040 18.065 17.789 WC4 16 0
24 [HS80] B215 a sg* 01 33 44.6258259338 +30 36 31.455406536   16.935 16.904     A0I 2 0
25 [HS80] B245 s*b 01 33 44.7681881983 +30 32 17.582887256   18.04 17.94     B8I 9 0
26 [HS80] 217a * 01 33 44.8 +30 36 18     17.40     ~ 7 0
27 D33 J013346.2+304439.9 EB* 01 33 46.17 +30 44 39.9   19.28 19.39   19.70 ~ 6 0
28 [MBH96] 215 EB* 01 33 50.3952186571 +30 38 33.733830325 15.922 15.944 16.335 15.751 15.610 B2Ib 12 0
29 M 33 GiG 01 33 50.8965749232 +30 39 36.630403128 6.17 6.27 5.72     ~ 6226 1
30 LAMOST J013351.20+303224.5 Ce* 01 33 51.1618064161 +30 32 24.327522156   21.75 21.16     B9I 5 0
31 [MBH96] 222 s*b 01 33 51.5214900409 +30 40 05.136826920 16.462 17.141 17.102 17.059 16.938 B9I 6 0
32 [HS80] B354 * 01 33 53.2114301008 +30 35 25.894729405 16.353 17.109 17.153 17.145 17.092 B1III: 9 0
33 Ass Per OB 1 As* 02 21 +57.6           ~ 181 1
34 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 19090 0
35 NAME Local Group GrG ~ ~           ~ 9325 0

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