2020A&A...634A..16M


Query : 2020A&A...634A..16M

2020A&A...634A..16M - Astronomy and Astrophysics, volume 634A, 16-16 (2020/2-1)

The VLT-FLAMES Tarantula Survey. XXXII. Low-luminosity late O-type stars: classification, main physical parameters, and silicon abundances.

MARKOVA N., PULS J., DUFTON P.L., LENNON D.J., EVANS C.J., DE KOTER A., RAMIREZ-AGUDELO O.H., SANA H. and VINK J.S.

Abstract (from CDS):

Analysis of late O-type stars observed in the Large Magellanic Cloud (LMC) by the VLT-FLAMES Tarantula Survey revealed a discrepancy between the physical properties estimated from model-atmosphere analysis and those expected from their morphological classifications. Here we revisit the analysis of 32 of these puzzling objects using new hydrogen-helium-siliconFASTWIND models and a different fitting approach to re-evaluate their physical properties. Our new analysis confirms that these stars indeed have properties that are typical of late O-type dwarfs. We also present the first estimates of silicon abundances for O-type stars in the 30 Dor clusters NGC 2060 and NGC 2070, with a weighted mean abundance for our sample of eSi=7.05±0.03. Our values are ∼0.20dex lower than those previously derived for B-type stars in the LMC clusters N 11 and NGC 2004 usingTLUSTY models. Various possibilities (e.g. differences in the analysis methods, effects of microturbulence, and real differences between stars in different clusters) were considered to account for these results. We also used our grid ofFASTWIND models to reassess the impact of using the Galactic classification criteria for late O-type stars in the LMC by scrutinising their sensitivity to different stellar properties. At the cool edge of the O star regime the HeIIλ4686/HeIλ4713 ratio used to assign luminosity class for Galactic stars can mimic giants or bright giants in the LMC, even for objects with high gravities (logg>4.0dex). We argue that this line ratio is not a reliable luminosity diagnostic for late O-type stars in the LMC, and that the SiIVλ4089/HeIλ4026 ratio is more robust for these types.

Abstract Copyright: © ESO 2020

Journal keyword(s): stars: abundances - stars: early-type - stars: fundamental parameters - stars: mass-loss - Magellanic Clouds

Simbad objects: 47

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Number of rows : 47
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9944 1
2 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 6045 1
3 LHA 120-N 11 HII 04 56 51.4 -66 24 24           ~ 241 0
4 NGC 1818 GlC 05 04 13.300 -66 26 05.47           ~ 243 0
5 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 15597 1
6 NGC 2004 Cl* 05 30 41.340 -67 17 21.83   9.6       ~ 267 0
7 VFTS 70 * 05 37 33.8838149800 -69 08 58.256780996   17.13 16.85     O9.7II 9 0
8 2MASS6X J05373512-6909411 * 05 37 35.1304003120 -69 09 41.198254581 16.016 16.729 16.635   16.552 O9.5:IIIn 10 0
9 [ST92] 1-23 * 05 37 35.7370178256 -69 08 07.471520536 15.739 16.528 16.297   15.927 O9.7II-III((n)) 12 0
10 [ST92] 1-27 * 05 37 37.5281291158 -69 08 20.457303894 15.424 16.202 16.068   15.692 O9.5IIIn 10 0
11 IRSF J05373989-6905468 * 05 37 40.036 -69 05 47.41   16.19 16.20     O9.7II-III((n)) 9 0
12 2MASS J05374092-6908442 SB* 05 37 40.8981993449 -69 08 44.203046852 16.052 16.829 16.633   16.491 O9/B0 12 0
13 VFTS 119 * 05 37 41.7166252359 -69 07 28.144290769   16.43 16.36     B0.7V 7 0
14 [M2002] LMC 169061 * 05 37 43.4022399966 -69 09 58.997881295   16.32 16.5     O9.5III:((n)) 11 0
15 VFTS 131 * 05 37 43.7432639772 -69 10 22.135175385   16.88 16.77     O9.7 8 0
16 VFTS 141 * 05 37 45.740 -69 09 13.33   15.36 15.32     O9.5II-III((n)) 11 0
17 NGC 2060 SNR 05 37 51.4470067818 -69 10 23.957283532   9.69 9.59     ~ 330 2
18 VFTS 188 * 05 37 52.3994305420 -69 10 51.202380930   17.12 16.82     O9.7:III: 9 0
19 [ST92] 1-85 * 05 37 53.6407 -69 10 12.488   16.22 16.3     O9/B0 11 0
20 [M2002] LMC 169602 * 05 37 55.3907310444 -69 10 20.796212803   15.9 16.1     O9/B0 11 0
21 [M2002] LMC 169636 * 05 37 56.0837949249 -69 10 38.931397722   16.31 16.4     O9.7II((n)) 11 0
22 UCAC2 1803310 * 05 37 56.9565885355 -69 08 21.163171095   15.6 15.8 15.95   O9.7II-III((n)) 10 0
23 NAME 30 Dor Region reg 05 38.0 -69 06           ~ 191 0
24 VFTS 226 * 05 38 00.9961404318 -69 14 21.677187154   15.89 15.92     O9.7III 9 0
25 VFTS 313 * 05 38 20.3763922076 -69 06 22.761624858   16.39 16.32     B0IV 8 0
26 VFTS 328 * 05 38 22.3265603628 -69 13 15.222824718   15.79 15.90     O9.5III(n) 9 0
27 VFTS 346 * 05 38 27.7586473142 -69 06 06.725267960   16.37 16.30     O9.7III 9 0
28 [P93] 222 * 05 38 30.740 -69 08 27.13   15.69 15.74     O9.7III 11 0
29 OGLE LMC-LPV-76549 LP* 05 38 34.76 -69 04 50.3   16.93 17.039   15.316 O9.7 11 0
30 NAME 30 Dor Nebula SFR 05 38 36.0 -69 05 11           ~ 1075 2
31 Cl* NGC 2070 SMB 233 * 05 38 38.020 -69 05 08.58   16.04 16.13   16.41 O9.7 11 0
32 2MASS J05384109-6901458 * 05 38 41.093 -69 01 45.88 14.684 15.333 15.556   15.477 O9.7II-IIIn 10 0
33 NGC 2070 Cl* 05 38 42 -69 06.0     7.25     ~ 342 1
34 [P93] 956 * 05 38 42.3779 -69 04 24.743   15.58 15.58     O9.7(n) 13 0
35 RMC 136 Cl* 05 38 42.396 -69 06 03.36           ~ 1823 1
36 Cl* NGC 2070 SMB 259 * 05 38 44.6850 -69 05 13.907   16.16 16.09   16.52 O9.2III: 13 0
37 Cl* NGC 2070 MH 917 * 05 38 44.700 -69 05 41.01   17.1 16.92   17.09 O9.5II-III(n) 11 0
38 VFTS 574 * 05 38 44.8250043019 -68 57 34.602413050   15.77 15.89     O9.5IIIn 9 0
39 Cl* NGC 2070 SMB 294 * 05 38 46.760 -69 05 48.75   16.42 16.34   16.40 O9.7III 13 0
40 Cl* NGC 2070 SMB 218 * 05 38 47.330 -69 06 17.70   15.91 15.89   15.89 O9.5IIInn 11 0
41 [P93] 1416 * 05 38 47.9176164478 -69 05 32.963356648   16.64 16.61   16.90 O9.7III(n) 12 0
42 Cl* NGC 2070 SMB 333 SB* 05 38 48.024 -69 06 12.27   16.61 16.56   16.63 O9.7III 11 0
43 2MASS J05384814-6907415 * 05 38 48.1362189672 -69 07 41.601771699 15.250 15.874 15.516   15.772 B0.2V 11 0
44 IRSF J05390915-6912104 * 05 39 09.145 -69 12 10.45   16.88 16.46     O9.7II-III 10 0
45 VFTS 787 SB* 05 39 24.7892052504 -69 05 51.614562760   16.68 16.53     O9.7III 8 0
46 VFTS 843 * 05 39 43.3792130201 -69 01 22.371080276   15.83 15.88     O9.5IIIn 9 0
47 NAME Local Group GrG ~ ~           ~ 7395 0

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2021.10.26-05:43:45

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