The Wolf-Rayet Content of M33

Neugent, Kathryn F.; Massey, Philip

doi:10.1088/0004-637x/733/2/123

Cited by 76 publications

(171 citation statements)

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“…However, unlike our newly-found WR of WO-type, the majority (11 out of 12) of the new stars presented in BAT99 are of WN-type. This is to be expected since, as discussed in Neugent & Massey (2011), the strongest emission feature in WCs is nearly 4× stronger than the strongest line in WNs (Conti & Massey 1989), making WNs much more difficult to detect. Therefore before BAT99, the ratio of un-detected WRs in the LMC was previously skewed towards WNs.…”

Section: Wolf-rayet Stars In the Large Magellanic Cloudmentioning

confidence: 75%

The Discovery of a Rare Wo-Type Wolf–rayet Star in the Large Magellanic Cloud

Neugent¹,

Massey²,

Morrell³

2012

The Astronomical Journal

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While observing OB stars within the most crowded regions of the Large Magellanic Cloud, we happened upon a new Wolf-Rayet star in Lucke-Hodge 41, the rich OB association that contains S Doradus and numerous other massive stars. At first glance the spectrum resembled that of a WC4 star, but closer examination showed strong OVI λλ 3811, 34 lines, leading us to classify it as a WO4. This is only the second known WO in the LMC, and the first known WO4 (the other being a WO3). This rarity is to be expected due to these stars' short lifespans as they represent the most advanced evolutionary stage in a massive star's lifetime before exploding as SNe. This discovery shows that while the majority of WRs within the LMC have been discovered, there may be a few WRs left to be found.

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Section: Wolf-rayet Stars In the Large Magellanic Cloudmentioning

confidence: 75%

The Discovery of a Rare Wo-Type Wolf–rayet Star in the Large Magellanic Cloud

Neugent¹,

Massey²,

Morrell³

2012

The Astronomical Journal

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“…While WN and WNh stars are expected to be systematically different (Crowther 2007;Smith & Conti 2008), this approach eases the comparison between the two galaxies. In M33, the Neugent & Massey (2011) catalogue only contains one WNh star. However, Hamann, Gräfener & Liermann (2006) listed many WNh stars in the Milky Way, providing circumstantial evidence that they should also exist in larger numbers in M33; one star in the Neugent & Massey (2011) catalogue is labeled "H-rich" but not classified WNh; one of the classification sources (Abbott et al 2004) intentionally omitted the Smith, Shara & Moffat (1996) WNh criteria; and one WN7h star from another source (Drissen et al 2008) is simply reported as a WN7 in Neugent & Massey (2011).…”

Section: Resultsmentioning

confidence: 99%

Core-collapse supernova progenitor constraints using the spatial distributions of massive stars in local galaxies

Kangas

Portinari

Mattila

et al. 2017

A&A

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We study the spatial correlations between the H α emission and different types of massive stars in two local galaxies, the Large Magellanic Cloud (LMC) and Messier 33. We compare these to correlations derived for core-collapse supernovae (CCSNe) in the literature to connect CCSNe of different types with the initial masses of their progenitors and to test the validity of progenitor mass estimates which use the pixel statistics method. We obtain samples of evolved massive stars in both galaxies from catalogues with good spatial coverage and/or completeness, and combine them with coordinates of main-sequence stars in the LMC from the SIMBAD database. We calculate the spatial correlation of stars of different classes and spectral types with H α emission. We also investigate the effects of distance, noise and positional errors on the pixel statistics method. A higher correlation with H α emission is found to correspond to a shorter stellar lifespan, and we conclude that the method can be used as an indicator of the ages, and therefore initial masses, of SN progenitors. We find that the spatial distributions of type II-P SNe and red supergiants of appropriate initial mass ( 9 M ) are consistent with each other. We also find the distributions of type Ic SNe and WN stars with initial masses 20 M consistent, while supergiants with initial masses around 15 M are a better match for type IIb and II-L SNe. The type Ib distribution corresponds to the same stellar types as type II-P, which suggests an origin in interacting binaries. On the other hand, we find that luminous blue variable stars show a much stronger correlation with H α emission than do type IIn SNe.

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“…It takes more time to reach deeper layers, and consequently these layers bear the imprint of the nucleosynthesis occurring at later stages of evolution. Neugent & Massey (2011) showed that the ratio WC/WN is correctly reproduced by the models of Meynet & Maeder (2003) at low metallicity. This is not the case at higher metallicity (see also Neugent et al 2012) where evolutionary models predict too few WC stars.…”

Section: Introductionmentioning

confidence: 82%

A comparison of evolutionary tracks for single Galactic massive stars

Martins

Palacios

2013

A&A

136

121

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Context. The evolution of massive stars is not fully understood. The relation between different types of evolved massive stars is not clear, and the role of factors such as binarity, rotation or magnetism needs to be quantified. Aims. Several groups make available the results of 1D single stellar evolution calculations in the form of evolutionary tracks and isochrones. They use different stellar evolution codes for which the input physics and its implementation varies. In this paper, we aim at comparing the currently available evolutionary tracks for massive stars. We focus on calculations aiming at reproducing the evolution of Galactic stars. Our main goal is to highlight the uncertainties on the predicted evolutionary paths. Methods. We compute stellar evolution models with the codes MESA and STAREVOL. We compare our results with those of four published grids of massive stellar evolution models (Geneva, STERN, Padova and FRANEC codes). We first investigate the effects of overshooting, mass loss, metallicity, chemical composition. We subsequently focus on rotation. Finally, we compare the predictions of published evolutionary models with the observed properties of a large sample of Galactic stars. Results. We find that all models agree well for the main sequence evolution. Large differences in luminosity and temperatures appear for the post main sequence evolution, especially in the cool part of the Hertzsprung-Russell (HR) diagram. Depending on the physical ingredients, tracks of different initial masses can overlap, rendering any mass estimate doubtful. For masses between 7 and 20 M , we find that the main sequence width is slightly too narrow in the Geneva models including rotation. It is (much) too wide for the (STERN) FRANEC models. This conclusion is reached from the investigation of the HR diagram and from the evolution of the surface velocity as a function of surface gravity. An overshooting parameter α between 0.1 and 0.2 in models with rotation is preferred to reproduce the main sequence width. Determinations of surface abundances of carbon and nitrogen are partly inconsistent and cannot be used at present to discriminate between the predictions of published tracks. For stars with initial masses larger than about 60 M , the FRANEC models with rotation can reproduce the observations of luminous O supergiants and WNh stars, while the Geneva models remain too hot.

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The Wolf-Rayet Content of M33

Cited by 76 publications

References 76 publications

The Discovery of a Rare Wo-Type Wolf–rayet Star in the Large Magellanic Cloud

The Discovery of a Rare Wo-Type Wolf–rayet Star in the Large Magellanic Cloud

Core-collapse supernova progenitor constraints using the spatial distributions of massive stars in local galaxies

A comparison of evolutionary tracks for single Galactic massive stars

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