2013ApJ...768....6M


Query : 2013ApJ...768....6M

2013ApJ...768....6M - Astrophys. J., 768, 6 (2013/May-1)

A bake-off between CMFGEN and FASTWIND: modeling the physical properties of SMC and LMC O-type stars.

MASSEY P., NEUGENT K.F., HILLIER D.J. and PULS J.

Abstract (from CDS):

The model atmosphere programs FASTWIND and CMFGEN are both elegantly designed to perform non-LTE analyses of the spectra of hot massive stars, and include sphericity and mass-loss. The two codes differ primarily in their approach toward line blanketing, with CMFGEN treating all of the lines in the co-moving frame and FASTWIND taking an approximate approach which speeds up execution times considerably. Although both have been extensively used to model the spectra of O-type stars, no studies have used the codes to independently model the same spectra of the same stars and compare the derived physical properties. We perform this task on 10 O-type stars in the Magellanic Clouds. For the late-type O supergiants, both CMFGEN and FASTWIND have trouble fitting some of the He I lines, and we discuss causes and cures. We find that there is no difference in the average effective temperatures found by the two codes for the stars in our sample, although the dispersion is large, due primarily to the various difficulties each code has with He I. The surface gravities determined using FASTWIND are systematically lower by 0.12 dex compared to CMFGEN, a result we attribute to the better treatment of electron scattering by CMFGEN. This has implications for the interpretation of the origin of the so-called mass discrepancy, as the masses derived by FASTWIND are on average lower than inferred from stellar evolutionary models, while those found by CMFGEN are in better agreement.

Abstract Copyright:

Journal keyword(s): stars: atmospheres - stars: early-type - stars: fundamental parameters

Simbad objects: 21

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Number of rows : 21
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 BBB SMC 266 s*b 00 47 50.0484011088 -73 08 21.054056928   12.35 12.55 12.36   O6I(f) 65 0
2 BBB SMC 1 * 00 50 17.2067283312 -72 53 30.259838832 12.093 13.144 13.326 13.39 13.47 OC7.5III((f)) 41 0
3 LIN 156 s*b 00 50 32.4050818488 -72 52 36.441355908 11.553 12.604 12.756   12.89 O5.5I(f) 48 0
4 AzV 83 s*b 00 50 52.0015192368 -72 42 14.940550980 12.233 13.244 13.366   13.67 O7Iaf+ 45 0
5 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 10367 1
6 AzV 177 * 00 56 44.1036082560 -72 03 31.678578504 13.22 14.39 14.62   14.90 O4Vz 24 0
7 AzV 223 * 00 59 13.4277067392 -72 39 02.635288236 12.36 13.47 13.67   13.95 O9.5II 15 0
8 Cl* NGC 346 ELS 22 * 00 59 18.6176208672 -72 11 09.887619084   14.65 14.91     O9V 19 0
9 AzV 233 * 00 59 34.8662246952 -72 42 54.628286400 13.47 14.43 14.64   14.86 B0 6 0
10 IC 1613 GiC 01 04 54.2 +02 08 00   10.42 10.01 9.77   ~ 1175 2
11 AzV 388 * 01 05 39.5306276568 -72 29 26.938329540 12.79 13.86 14.12   14.37 O5V 39 0
12 M 33 GiG 01 33 50.8965749232 +30 39 36.630403128 6.17 6.27 5.72     ~ 5538 1
13 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 6412 1
14 SK -70 69 * 05 05 18.6717716496 -70 25 49.874974104 12.586 13.616 13.854   14.074 O3V(f) 39 0
15 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16252 1
16 SK -69 124 * 05 25 18.2515805760 -69 03 11.489785740 11.583 12.664 12.826   12.791 OB 24 0
17 BI 170 * 05 26 47.6917783584 -69 06 12.016345140 11.823 12.914 13.116   12.975 O9.5Ib 25 0
18 W61 28-23 * 05 34 50.1539297904 -69 46 32.544537024 12.698 13.596 13.702   13.752 O3.5V(f+) 12 0
19 V* AG Car WR* 10 56 11.5781414448 -60 27 12.810673260 7.00 7.57 6.96 7.73   WN11h 614 0
20 Ass Cyg OB 2 As* 20 33.2 +41 19           ~ 881 0
21 NAME Local Group GrG ~ ~           ~ 7768 0

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2022.09.28-08:34:14

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