2013A&A...559A..72T


Query : 2013A&A...559A..72T

2013A&A...559A..72T - Astronomy and Astrophysics, volume 559A, 72-72 (2013/11-1)

On the nature of WO stars: a quantitative analysis of the WO3 star DR1 in IC 1613.

TRAMPER F., GRAEFENER G., HARTOOG O.E., SANA H., DE KOTER A., VINK J.S., ELLERBROEK L.E., LANGER N., GARCIA M., KAPER L. and DE MINK S.E.

Abstract (from CDS):

Oxygen sequence Wolf-Rayet (WO) stars are thought to represent the final evolutionary stage of the most massive stars. The characteristic strong OVI emission possibly originates from an enhanced oxygen abundance in the stellar wind. Alternatively, the OVI emission can be caused by the high temperature of these stars, in which case the WO stars are the high-temperature extension of the more common carbon sequence Wolf-Rayet (WC) stars. By constraining the physical properties and evolutionary status of DR1, a WO star in the low-metallicity Local Group dwarf galaxy IC 1613 and one of only two objects of its class known in a SMC-like metallicity environment, we aim to investigate the nature of WO stars and their evolutionary connection with WC stars. We use the non-local thermodynamic equilibrium atmosphere code cmfgen to model the observed spectrum of DR1 and to derive its stellar and wind parameters. We compare our values with other studies of WC and WO stars, as well as with the predictions of evolutionary models. We also model the surrounding nebula using the photo-ionization code cloudy. The oxygen and carbon abundances that we obtain are comparable to values found for WC stars. The temperature and luminosity are, however, higher than those of WC stars. DR1 is embedded in the hottest known HII region in the Local Group. The nebular properties can be consistently reproduced by cloudy models adopting DR1 as central ionizing source. Comparison of the abundances and temperature of DR1 with core helium-burning models show that DR1 is currently well into the second half of helium burning. If the properties of DR1 are representative for the WO class, it would imply that WO stars are the high-temperature and high-luminosity extension of the WC stars, and do not necessarily represent a later evolutionary stage.

Abstract Copyright:

Journal keyword(s): stars: Wolf-Rayet - stars: massive - stars: individual: DR1 - galaxies: individual: IC 1613 - HII regions

Simbad objects: 16

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Number of rows : 16
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 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 11950 1
2 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 10392 1
3 IC 1613 GiC 01 04 54.2 +02 08 00   10.42 10.01 9.77   ~ 1175 2
4 [AM85] IC 1613 6 WR* 01 05 01.6177966440 +02 04 19.938198792     20.7     WO3 21 1
5 [HLG90] 37 HII 01 05 03.3 +02 04 24           ~ 19 0
6 LIN 547 WR* 01 31 04.1367366432 -73 25 03.784411524   12.75 12.90     WO4+O4V 92 0
7 [H2013] LMCe 584 * 05 18 11.01 -69 13 11.3 12.88 14.26 13.95     WO4 11 0
8 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16281 1
9 M 42 HII 05 35 17.3 -05 23 28           ~ 3939 0
10 Brey 93 WR* 05 39 34.3017622440 -68 44 09.155562972 14.291 15.626 15.204   15.620 WO3 64 0
11 [MS70] 4 WR* 10 51 38.9063499504 -60 56 34.909328328 13.57 13.80 12.78 12.56   WO4+O5III/V((f)) 50 0
12 WR 93b WR* 17 32 03.3086687328 -35 04 32.620100844           WO3 16 0
13 V* V3893 Sgr WR* 17 45 47.5405102320 -26 10 26.779355616   15.13 14.20 14.23   WR 113 1
14 DR 1 Rad 20 16.6 +41 42           ~ 12 1
15 WR 142 WR* 20 21 44.3438785440 +37 22 30.544989960   14.39 12.99 12.73 11.04 WO2 126 0
16 NAME Local Group GrG ~ ~           ~ 7778 0

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2022.10.06-15:30:30

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