Li-rich giant stars under scrutiny: binarity, magnetic activity, and the evolutionary status after Gaia DR2
We present a study of the evolutionary state of a few lithium-rich giant stars based on the Gaia Data Release 2 (DR2) parallaxes and photometry. We also investigate the chromospheric activity, the presence of a surface magnetic field, and the radial velocity for our sample stars. We analysed both ar...
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ri-123456789-310052020-12-20T07:59:21Z Li-rich giant stars under scrutiny: binarity, magnetic activity, and the evolutionary status after Gaia DR2 Costa, Jefferson Soares da Almeida, Leandro de Castro, Matthieu Sebastien Nascimento Júnior, José Dias do Gonçalves, B. F. O Techniques: radial velocities – techniques Spectroscopic – stars Abundances – stars Evolution – stars Late-type – stars Magnetic field We present a study of the evolutionary state of a few lithium-rich giant stars based on the Gaia Data Release 2 (DR2) parallaxes and photometry. We also investigate the chromospheric activity, the presence of a surface magnetic field, and the radial velocity for our sample stars. We analysed both archive and new data. We gathered archive spectra from several instruments, mainly ELODIE and NARVAL, and we added new data acquired with the spectrograph MUSICOS. We applied the least-squares deconvolution technique to obtain Stokes V and I mean profiles to compute longitudinal magnetic field for a subset. Moreover, for the same subset, we analysed the Ca II H&K emission lines to calculate the S-index. We also derived atmospheric parameters and Li abundances for all 18 stars of our sample. We found that stars previously classified as red giant branch (RGB) may actually be at a different evolutionary state. Furthermore, we identified that most stars in our sample with detection of surface magnetic field show at least moderate rotation velocities, but none the less, we could not detect a magnetic field in two fast rotators. Because of our small sample of magnetic giants, it is difficult to determine if the presence of surface magnetic field and the Li-rich giant phenomena could be somehow linked. The large variation of the radial velocity of part of our sample indicates that some of them might have a binary companion, which may change the way we look at the Li problem in giant stars 2020-12-15T19:44:08Z 2020-12-15T19:44:08Z 2020-09-02 article GONÇALVES, B F O; DA COSTA, J. S.; ALMEIDA, L; CASTRO, M; NASCIMENTO, J. D. Li-rich giant stars under scrutiny: binarity, magnetic activity, and the evolutionary status after gaia dr2. Monthly Notices of the Royal Astronomical Society, [S.L.], v. 498, n. 2, p. 2295-2308, 2 set. 2020. Disponível em: https://academic.oup.com/mnras/article-abstract/498/2/2295/5900561?redirectedFrom=fulltext. Acesso em: 07 out. 2020. http://dx.doi.org/10.1093/mnras/staa2408. 0035-8711 1365-2966 https://repositorio.ufrn.br/handle/123456789/31005 10.1093/mnras/staa2408 en application/pdf Oxford University Press |
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RI - UFRN |
| language |
English |
| topic |
Techniques: radial velocities – techniques Spectroscopic – stars Abundances – stars Evolution – stars Late-type – stars Magnetic field |
| spellingShingle |
Techniques: radial velocities – techniques Spectroscopic – stars Abundances – stars Evolution – stars Late-type – stars Magnetic field Costa, Jefferson Soares da Almeida, Leandro de Castro, Matthieu Sebastien Nascimento Júnior, José Dias do Gonçalves, B. F. O Li-rich giant stars under scrutiny: binarity, magnetic activity, and the evolutionary status after Gaia DR2 |
| description |
We present a study of the evolutionary state of a few lithium-rich giant stars based on the Gaia Data Release 2 (DR2) parallaxes and photometry. We also investigate the chromospheric activity, the presence of a surface magnetic field, and the radial velocity for our sample stars. We analysed both archive and new data. We gathered archive spectra from several instruments, mainly ELODIE and NARVAL, and we added new data acquired with the spectrograph MUSICOS. We applied the least-squares deconvolution technique to obtain Stokes V and I mean profiles to compute longitudinal magnetic field for a subset. Moreover, for the same subset, we analysed the Ca II H&K emission lines to calculate the S-index. We also derived atmospheric parameters and Li abundances for all 18 stars of our sample. We found that stars previously classified as red giant branch (RGB) may actually be at a different evolutionary state. Furthermore, we identified that most stars in our sample with detection of surface magnetic field show at least moderate rotation velocities, but none the less, we could not detect a magnetic field in two fast rotators. Because of our small sample of magnetic giants, it is difficult to determine if the presence of surface magnetic field and the Li-rich giant phenomena could be somehow linked. The large variation of the radial velocity of part of our sample indicates that some of them might have a binary companion, which may change the way we look at the Li problem in giant stars |
| format |
article |
| author |
Costa, Jefferson Soares da Almeida, Leandro de Castro, Matthieu Sebastien Nascimento Júnior, José Dias do Gonçalves, B. F. O |
| author_facet |
Costa, Jefferson Soares da Almeida, Leandro de Castro, Matthieu Sebastien Nascimento Júnior, José Dias do Gonçalves, B. F. O |
| author_sort |
Costa, Jefferson Soares da |
| title |
Li-rich giant stars under scrutiny: binarity, magnetic activity, and the evolutionary status after Gaia DR2 |
| title_short |
Li-rich giant stars under scrutiny: binarity, magnetic activity, and the evolutionary status after Gaia DR2 |
| title_full |
Li-rich giant stars under scrutiny: binarity, magnetic activity, and the evolutionary status after Gaia DR2 |
| title_fullStr |
Li-rich giant stars under scrutiny: binarity, magnetic activity, and the evolutionary status after Gaia DR2 |
| title_full_unstemmed |
Li-rich giant stars under scrutiny: binarity, magnetic activity, and the evolutionary status after Gaia DR2 |
| title_sort |
li-rich giant stars under scrutiny: binarity, magnetic activity, and the evolutionary status after gaia dr2 |
| publisher |
Oxford University Press |
| publishDate |
2020 |
| url |
https://repositorio.ufrn.br/handle/123456789/31005 |
| work_keys_str_mv |
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| _version_ |
1773967166820843520 |