A population analysis of Galactic Miras with light-curve asymmetries
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866916840898297856 |
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| author | Uttenthaler, Stefan Merchan-Benitez, Pedro |
| author_facet | Uttenthaler, Stefan Merchan-Benitez, Pedro |
| contents | Context: In a recent publication, we established a close relationship between light-curve asymmetries in Mira variables and indicators of their dust mass-loss rate. The light-curve asymmetries appear to be related to the stars' third dredge-up (3DUP) activity. Aims: We aim to reveal the evolutionary status of M-type Miras with light-curve asymmetries ('bumps') within the spectral sequence M -- S -- C, determine their mass-loss properties, and check possible evolutionary scenarios. Methods: We analysed a sample of 3100 Miras collected from the ASAS database, distinguishing between symmetric and asymmetric light curves. We determined their periods, luminosity functions, and period-luminosity relations, their locations relative to the Galactic midplane, as well as mass-loss rate indicators through the 2MASS-WISE colours and the Gaia-2MASS diagram. Results: The M-type Miras with symmetric light curves are generally found to have shorter periods, lower luminosities, a larger average distance to the Galactic midplane, and lower initial masses than the M-type Miras with asymmetries. In addition, 25 Miras are proposed as candidates for new carbon stars. Conclusions: We propose that the M-type Miras have two distinct populations: M-type Miras with symmetric light curves, which have lower initial mass progenitors than M-type Miras with asymmetries, which show signs of 3DUP activity and are the link to the S-type Miras. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2507_09653 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A population analysis of Galactic Miras with light-curve asymmetries Uttenthaler, Stefan Merchan-Benitez, Pedro Solar and Stellar Astrophysics Astrophysics of Galaxies Context: In a recent publication, we established a close relationship between light-curve asymmetries in Mira variables and indicators of their dust mass-loss rate. The light-curve asymmetries appear to be related to the stars' third dredge-up (3DUP) activity. Aims: We aim to reveal the evolutionary status of M-type Miras with light-curve asymmetries ('bumps') within the spectral sequence M -- S -- C, determine their mass-loss properties, and check possible evolutionary scenarios. Methods: We analysed a sample of 3100 Miras collected from the ASAS database, distinguishing between symmetric and asymmetric light curves. We determined their periods, luminosity functions, and period-luminosity relations, their locations relative to the Galactic midplane, as well as mass-loss rate indicators through the 2MASS-WISE colours and the Gaia-2MASS diagram. Results: The M-type Miras with symmetric light curves are generally found to have shorter periods, lower luminosities, a larger average distance to the Galactic midplane, and lower initial masses than the M-type Miras with asymmetries. In addition, 25 Miras are proposed as candidates for new carbon stars. Conclusions: We propose that the M-type Miras have two distinct populations: M-type Miras with symmetric light curves, which have lower initial mass progenitors than M-type Miras with asymmetries, which show signs of 3DUP activity and are the link to the S-type Miras. |
| title | A population analysis of Galactic Miras with light-curve asymmetries |
| topic | Solar and Stellar Astrophysics Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2507.09653 |