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| Autores principales: | , , , , , |
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| Formato: | Preprint |
| Publicado: |
2025
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| Acceso en línea: | https://arxiv.org/abs/2507.19249 |
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| _version_ | 1866909705259974656 |
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| author | Kraus, Michaela Arias, Maria Laura Kourniotis, Michalis Torres, Andrea Cidale, Lydia S. Fernandes, Marcelo Borges |
| author_facet | Kraus, Michaela Arias, Maria Laura Kourniotis, Michalis Torres, Andrea Cidale, Lydia S. Fernandes, Marcelo Borges |
| contents | The upper region of the Hertzsprung-Russell diagram is populated by massive stars in a diversity of evolutionary stages, and the classification of these stars is often based on observed characteristics exclusively in the optical spectral range. The near-infrared regime provides useful complementary information that can help resolving ambiguities in stellar classification and add valuable information about circumstellar envelopes or late-type companions. We present new, near-infrared medium-resolution K-band spectra for a sample of six evolved massive stars, four in M31 and two in M33. The spectra are obtained with the Gemini Near-Infrared Spectrograph (GNIRS) at the Gemini North telescope. We detect CO band emission from the environment of two M31 objects, J004320.97+414039.6 and J004621.08+421308.2, which we classify as B[e] supergiants, with J004320.97+414039.6 being most likely in a post-red supergiant stage. Two objects have pure emission from the hydrogen Pfund series. Of these, we propose that J004415.00+420156.2 in M31 could also be a B[e] supergiant while J013410.93+303437.6 (Var 83) is a well-known luminous blue variable (LBV) in M33. The M31 star J004229.87+410551.8 has a featureless spectrum and its evolutionary stage remains inconclusive; it could be an LBV undergoing an S Dor cycle. The object J013242.26+302114.1 in M33 displays a pure absorption spectrum, including CO bands, consistent with its identification as a cool star. Radial velocity measurements of this red component, combined with modelling of the spectral energy distribution, suggest that J013242.26+302114.1 may be a binary system consisting of an LBV or B[e] supergiant primary and a red supergiant secondary. If confirmed, it would represent the first of its kind. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_19249 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Near-infrared characterization of evolved massive stars in M31 and M33 Kraus, Michaela Arias, Maria Laura Kourniotis, Michalis Torres, Andrea Cidale, Lydia S. Fernandes, Marcelo Borges Solar and Stellar Astrophysics Astrophysics of Galaxies The upper region of the Hertzsprung-Russell diagram is populated by massive stars in a diversity of evolutionary stages, and the classification of these stars is often based on observed characteristics exclusively in the optical spectral range. The near-infrared regime provides useful complementary information that can help resolving ambiguities in stellar classification and add valuable information about circumstellar envelopes or late-type companions. We present new, near-infrared medium-resolution K-band spectra for a sample of six evolved massive stars, four in M31 and two in M33. The spectra are obtained with the Gemini Near-Infrared Spectrograph (GNIRS) at the Gemini North telescope. We detect CO band emission from the environment of two M31 objects, J004320.97+414039.6 and J004621.08+421308.2, which we classify as B[e] supergiants, with J004320.97+414039.6 being most likely in a post-red supergiant stage. Two objects have pure emission from the hydrogen Pfund series. Of these, we propose that J004415.00+420156.2 in M31 could also be a B[e] supergiant while J013410.93+303437.6 (Var 83) is a well-known luminous blue variable (LBV) in M33. The M31 star J004229.87+410551.8 has a featureless spectrum and its evolutionary stage remains inconclusive; it could be an LBV undergoing an S Dor cycle. The object J013242.26+302114.1 in M33 displays a pure absorption spectrum, including CO bands, consistent with its identification as a cool star. Radial velocity measurements of this red component, combined with modelling of the spectral energy distribution, suggest that J013242.26+302114.1 may be a binary system consisting of an LBV or B[e] supergiant primary and a red supergiant secondary. If confirmed, it would represent the first of its kind. |
| title | Near-infrared characterization of evolved massive stars in M31 and M33 |
| topic | Solar and Stellar Astrophysics Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2507.19249 |