Optical spectroscopic signatures of the red giant evolutionary state
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arXiv
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| Autores principales: | , , , , , , , , , , , , , , , , , , , |
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| Formato: | Preprint |
| Publicado: |
2025
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| author | Wang, Ella Xi Ness, Melissa Nordlander, Thomas Casey, Andrew R. Martell, Sarah Pinsonneault, Marc Fu, Xiaoting Stello, Dennis Reyes, Claudia Hon, Marc McKenzie, Madeleine Jian, Mingjie Yu, Jie Buder, Sven Lind, Karin Bland-Hawthorn, Joss Zucker, Daniel B. Das, Pradosh Barun de Grijs, Richard Hayden, Michael |
| author_facet | Wang, Ella Xi Ness, Melissa Nordlander, Thomas Casey, Andrew R. Martell, Sarah Pinsonneault, Marc Fu, Xiaoting Stello, Dennis Reyes, Claudia Hon, Marc McKenzie, Madeleine Jian, Mingjie Yu, Jie Buder, Sven Lind, Karin Bland-Hawthorn, Joss Zucker, Daniel B. Das, Pradosh Barun de Grijs, Richard Hayden, Michael |
| contents | Modern spectroscopic surveys output large data volumes. Theoretical models provide a means to transform the information encoded in these data to measurements of physical stellar properties. However, in detail the models are incomplete and simplified, and prohibit interpretation of the fine details in spectra. Instead, the available data provide an opportunity to use data-driven, differential analysis techniques, as a means towards understanding spectral signatures. We deploy such an analysis to examine core helium-fusing red clump (RC) and shell hydrogen-fusing red giant branch (RGB) stars, to uncover signatures of evolutionary state imprinted in optical stellar spectra. We exploit 786 pairs of RC and RGB stars from the GALAH survey, chosen to minimise spectral differences, with evolutionary state classifications from TESS and K2 asteroseismology. We report sub-percent residual, systematic spectral differences between the two classes of stars, and show that these residuals are significant compared to a reference sample of RC$-$RC and RGB$-$RGB pairs selected using the same criteria. First, we report systematic differences in the Swan ($\rm{C}_2$) band and CN bands caused by stellar evolution and a difference in mass, where RGB stars at similar stellar parameters have higher masses than RC stars. Secondly, we observe systematic differences in the line-width of the H$_α$ and H$_β$ lines caused by a difference in microturbulence, as measured by GALAH, where we measure higher microturbulence in RC stars than RGB stars. This work demonstrates the ability of large surveys to uncover the subtle spectroscopic signatures of stellar evolution using model-free, data-driven methods. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_02889 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Optical spectroscopic signatures of the red giant evolutionary state Wang, Ella Xi Ness, Melissa Nordlander, Thomas Casey, Andrew R. Martell, Sarah Pinsonneault, Marc Fu, Xiaoting Stello, Dennis Reyes, Claudia Hon, Marc McKenzie, Madeleine Jian, Mingjie Yu, Jie Buder, Sven Lind, Karin Bland-Hawthorn, Joss Zucker, Daniel B. Das, Pradosh Barun de Grijs, Richard Hayden, Michael Solar and Stellar Astrophysics Astrophysics of Galaxies Modern spectroscopic surveys output large data volumes. Theoretical models provide a means to transform the information encoded in these data to measurements of physical stellar properties. However, in detail the models are incomplete and simplified, and prohibit interpretation of the fine details in spectra. Instead, the available data provide an opportunity to use data-driven, differential analysis techniques, as a means towards understanding spectral signatures. We deploy such an analysis to examine core helium-fusing red clump (RC) and shell hydrogen-fusing red giant branch (RGB) stars, to uncover signatures of evolutionary state imprinted in optical stellar spectra. We exploit 786 pairs of RC and RGB stars from the GALAH survey, chosen to minimise spectral differences, with evolutionary state classifications from TESS and K2 asteroseismology. We report sub-percent residual, systematic spectral differences between the two classes of stars, and show that these residuals are significant compared to a reference sample of RC$-$RC and RGB$-$RGB pairs selected using the same criteria. First, we report systematic differences in the Swan ($\rm{C}_2$) band and CN bands caused by stellar evolution and a difference in mass, where RGB stars at similar stellar parameters have higher masses than RC stars. Secondly, we observe systematic differences in the line-width of the H$_α$ and H$_β$ lines caused by a difference in microturbulence, as measured by GALAH, where we measure higher microturbulence in RC stars than RGB stars. This work demonstrates the ability of large surveys to uncover the subtle spectroscopic signatures of stellar evolution using model-free, data-driven methods. |
| title | Optical spectroscopic signatures of the red giant evolutionary state |
| topic | Solar and Stellar Astrophysics Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2506.02889 |