A Multiwavelength Survey of Wolf–Rayet Nebulae in the Large Magellanic Cloud

Hung, Clara Shang; Ou, Po-Sheng; Chu, You‐Hua; Gruendl, R. A.; Li, Chuan-Jui

doi:10.3847/1538-4365/abcc00

“…The stars with WN/C characteristics were discovered as in M33 (Schild et al 1990), as well as in other galaxies, e.g., in the Large Magellanic Cloud (Breysacher et al 1999;Shenar et al 2019;Hung et al 2021), in the nearby spiral galaxy M81 (Gómez-González et al 2016, 2020, and in our Galaxy (Zhang et al 2020b). Recently, the first transition WN/C star was discovered in M31 (Shara et al 2016).…”

Section: Ngc 595mentioning

confidence: 93%

Spectroscopic Study of M33 with the LAMOST Survey. I. Chemical Gradients from Nebulae

Alexeeva¹,

Zhao

²

2022

ApJ

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Morphological and chemical structures of M33 are investigated with the LAMOST DR7 survey. Physical parameters; extinction; chemical composition of He, N, O, Ne, S, Cl, and Ar (where available); and radial velocities were determined for 110 nebulae (95 H ii regions and 15 planetary nebulae) in M33. Among them, 8 planetary nebulae and 55 H ii regions in M33 are newly discovered. We obtained the following O abundance gradients: − 0.199 − 0.030 + 0.030 dex R 25 − 1 (based on 95 H ii regions), − 0.124 − 0.036 + 0.036 dex R 25 − 1 (based on 93 H ii regions), and − 0.207 − 0.174 + 0.160 dex R 25 − 1 (based on 21 H ii regions), utilizing abundances from N2 at O3N2 diagnostics and the T e -sensitive method, respectively. The He, N, Ne, S, and Ar gradients resulted in slopes of − 0.179 − 0.146 + 0.145 , − 0.431 − 0.281 + 0.282 , − 0.171 − 0.239 + 0.234 , − 0.417 − 0.182 + 0.174 , and − 0.340 − 0.157 + 0.156 , respectively, utilizing abundances from the T e -sensitive method. Our results confirm the existence of the negative axisymmetric global metallicity distribution that is assumed in the literature. We noticed one new WC star candidate and one transition W-R WN/C candidate. The grand-design pattern of the spiral structure of M33 is presented.

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“…The mid-IR spectrum of LHA 120-S 134, obtained with the Spitzer Space Telescope, shows intense 10 µm and weak 20 µm emission features of amorphous silicate dust, and a faint and wispy nebulosity around the IR bright star was found with the telescope's imaging facilities [93]. Follow-up optical imaging revealed that LHA 120-S 134 is located on the northeast rim of the superbubble of DEM L269 and on the western rim of the H II region SGS LMC-2 [98]. Therefore, it is unclear if and how much of the optical and IR nebulosity might be related to LHA 120-S 134 itself.…”

Section: Lha 120-s 134 (=Hd 38489 Sk −69 259 Mwc 126)mentioning

confidence: 93%

Dense Molecular Environments of B[e] Supergiants and Yellow Hypergiants

Kraus

¹

,

Kourniotis

²

,

Arias

³

et al. 2023

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Massive stars expel large amounts of mass during their late evolutionary phases. We aim to unveil the physical conditions within the warm molecular environments of B[e] supergiants (B[e]SGs) and yellow hypergiants (YHGs), which are known to be embedded in circumstellar shells and disks. We present K-band spectra of two B[e]SGs from the Large Magellanic Cloud and four Galactic YHGs. The CO band emission detected from the B[e]SGs LHA 120-S 12 and LHA 120-S 134 suggests that these stars are surrounded by stable rotating molecular rings. The spectra of the YHGs display a rather diverse appearance. The objects 6 Cas and V509 Cas lack any molecular features. The star [FMR2006] 15 displays blue-shifted CO bands in emission, which might be explained by a possible close to pole-on oriented bipolar outflow. In contrast, HD 179821 shows blue-shifted CO bands in absorption. While the star itself is too hot to form molecules in its outer atmosphere, we propose that it might have experienced a recent outburst. We speculate that we currently can only see the approaching part of the expelled matter because the star itself might still block the receding parts of a (possibly) expanding gas shell.

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“…The size of a stellar windblown bubble directly correlates with its age (Weaver et al 1977;Freyer et al 2003Freyer et al , 2006, suggesting that the younger N76 nebula will be smaller than NGC 6888. Observations of WR nebulae in the LMC show the traditional bubble structure, i.e., a large cavity with a thin, photoionized shell of material in the majority of nebulae (Hung et al 2021).…”

Section: Comparison With Other Wr Nebulaementioning

confidence: 99%

Modeling Ionized Gas in the Small Magellanic Cloud: The Wolf–Rayet Nebula N76

Tarantino,

Bolatto,

Indebetouw

et al. 2024

ApJ

0

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We present Cloudy modeling of infrared emission lines in the Wolf–Rayet (WR) nebula N76 caused by one of the most luminous and hottest WR stars in the low metallicity Small Magellanic Cloud. We use spatially resolved mid-infrared Spitzer/InfRared Spectrograph and far-infrared Herschel/PACS spectroscopy to establish the physical conditions of the ionized gas. The spatially resolved distribution of the emission allows us to constrain properties much more accurately than using spatially integrated quantities. We construct models with a range of constant hydrogen densities between nH = 4–10 cm−3 and a stellar wind-blown cavity of 10 pc, which reproduces the intensity and shape of most ionized gas emission lines, including the high ionization lines [O iv] and [Ne v], as well as [S iii], [S iv], [O iii], and [Ne iii]. Our models suggest that the majority of [Si ii] emission (91%) is produced at the edge of the H ii region around the transition between ionized and atomic gas while very little of the [C ii] (<5%) is associated with the ionized gas. The physical conditions of N76 are characterized by a hot HII region with a maximum electron temperature of T e ∼ 24,000 K, electron densities that range from n e ∼ 4 to 12 cm−3, and high ionization parameters of log ( U ) ∼ − 1.15 to − 1.77 . By analyzing a low-metallicity WR nebula with a single ionization source, this work gives valuable insights into the impact WR stars have on the galaxy-integrated ionized gas properties in nearby dwarf galaxies.

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A Multiwavelength Survey of Wolf–Rayet Nebulae in the Large Magellanic Cloud

Cited by 10 publications

References 59 publications

Spectroscopic Study of M33 with the LAMOST Survey. I. Chemical Gradients from Nebulae

Spectroscopic Study of M33 with the LAMOST Survey. I. Chemical Gradients from Nebulae

Dense Molecular Environments of B[e] Supergiants and Yellow Hypergiants

Modeling Ionized Gas in the Small Magellanic Cloud: The Wolf–Rayet Nebula N76

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