| Issue |
A&A
Volume 645, January 2021
|
|
|---|---|---|
| Article Number | A19 | |
| Number of page(s) | 14 | |
| Section | Stellar atmospheres | |
| DOI | https://doi.org/10.1051/0004-6361/202039397 | |
| Published online | 22 December 2020 | |
Stellar population astrophysics (SPA) with the TNG★,★★
The Arcturus Lab
1
Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna,
via Piero Gobetti 93/2,
40129
Bologna, Italy
e-mail: cristiano.fanelli3@unibo.it
2
INAF-Osservatorio di Astrofisica e Scienza dello Spazio,
via Piero Gobetti 93/3,
40129
Bologna, Italy
3
INAF-Osservatorio Astrofisico di Arcetri,
Largo Enrico Fermi 5,
50125
Firenze, Italy
Received:
11
September
2020
Accepted:
30
October
2020
Context. High-resolution spectroscopy in the near-infrared (NIR) is a powerful tool for characterising the physical and chemical properties of cool-star atmospheres. The current generation of NIR echelle spectrographs enables the sampling of many spectral features over the full 0.9–2.4 μm range for a detailed chemical tagging.
Aims. Within the Stellar Population Astrophysics Large Program at the TNG, we used a high-resolution (R = 50 000) NIR spectrum of Arcturus acquired with the GIANO-B echelle spectrograph as a laboratory to define and calibrate an optimal line list and new diagnostic tools to derive accurate stellar parameters and chemical abundances.
Methods. We inspected several hundred NIR atomic and molecular lines to derive abundances of 26 different chemical species, including CNO, iron-group, alpha, Z-odd, and neutron-capture elements. We then performed a similar analysis in the optical using Arcturus VLT-UVES spectra.
Results. Through the combined NIR and optical analysis we defined a new thermometer and a new gravitometer for giant stars, based on the comparison of carbon (for the thermometer) and oxygen (for the gravitometer) abundances, as derived from atomic and molecular lines. We then derived self-consistent stellar parameters and chemical abundances of Arcturus over the full 4800–24 500 Å spectral range and compared them with previous studies in the literature. We finally discuss a number of problematic lines that may be affected by deviations from thermal equilibrium and/or chromospheric activity, as traced by the observed variability of He I at 10 830 Å.
Key words: techniques: spectroscopic / stars: abundances / stars: individual: Arcturus / stars: late-type
Tables A.1–A.4 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/645/A19
Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. This study is part of the Large Program titled SPA – Stellar Population Astrophysics: the detailed, age-resolved chemistry of the Milky Way disk (PI: L. Origlia), granted observing time with HARPS-N and GIANO-B echelle spectrographs at the TNG.
© ESO 2020
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