The Lines are Not Fine: Measuring Vanadium Abundances in M dwarfs from Hyperfine-Split Lines
| Main Authors: | Shan, Yutong, Reiners, Ansgar, Fabbian, Damian, Marfil, Emilio, Montes, David, Tabernero, Hugo M, Ribas, Ignasi, Caballero, Jose A., Quirrenbach, Andreas, Amado, Pedro J., Aceituno, J., Bejar, Victor J. S., Cortes-Contreras, Miriam, Dreizler, Stefan, Hatzes, Artie P., Henning, Thomas, Jeffers, Sandra V., Kaminski, Adrian, Kürster, Martin, Lafarga, Marina, Morales, Juan Carlos, Nagel, Evangelos, Rodriguez-Lopez, Cristina, Passegger, Vera M., Schweitzer, Andreas, Zechmeister, Mathias |
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| Other Authors: | Wolk, Scott |
| Format: | Proceeding poster Journal |
| Terbitan: |
, 2021
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| Subjects: | |
| Online Access: |
https://zenodo.org/record/4565083 |
Daftar Isi:
- Cool star atmospheres present challenges to chemical abundance studies. To date, only a handful of elements have been quantified for a handful of M dwarfs. In high-resolution spectra from the CARMENES survey, we identify a series of dramatically hyperfine-split vanadium features between 800 and 910 nm, which have strong and clean profiles throughout the early M-dwarf range. These ‘bucket-shaped’ line regions can be well-modeled with standard model atmospheres combined with the latest atomic data from VALD. From these line regions, we measure vanadium abundances for 140 nearby early M dwarfs in the CARMENES GTO sample and confirm that they follow the same trend with metallicity as the FG-type stars in the solar neighborhood, i.e., significantly above predictions from galactic chemical evolution models. Exhibiting a tight correlation with iron, vanadium abundances show promise as a potential metallicity indicator for M dwarfs. We also present evidence that several well-known chemical studies of K dwarfs have systematically overestimated their vanadium abundances largely as a result of neglecting to model hyperfine structure, a bias that worsens with decreasing temperature. Our work highlights opportunities for robust chemical analysis of cool stars afforded by high-quality spectra redward of visible.