Volume 629, September 2019
|Number of page(s)||9|
|Section||Galactic structure, stellar clusters and populations|
|Published online||13 September 2019|
Stellar population astrophysics (SPA) with the TNG
GIANO-B spectroscopy of red supergiants in Alicante 7 and Alicante 10⋆
INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Gobetti 93/3, 40129 Bologna, Italy
2 INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
3 Dipartimento di Fisica e Astronomia, Universitá degli Studi di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
4 INAF – Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, 34143 Trieste, Italy
5 Dipartimento di Fisica e Astronomia, Universitá degli Studi di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma, Italy
6 INAF – Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monte Porzio Catone, Italy
Accepted: 12 August 2019
Aims. The Scutum complex in the inner disk of the Galaxy hosts a number of young clusters and associations of red supergiant stars that are heavily obscured by dust extinction. These stars are important tracers of the recent star formation and chemical enrichment history in the inner Galaxy.
Methods. Within the SPA Large Programme at the TNG, we secured GIANO-B high-resolution (R ≃ 50 000) YJHK spectra of 11 red supergiants toward the Alicante 7 and Alicante 10 associations near the RSGC3 cluster. Taking advantage of the full YJHK spectral coverage of GIANO in a single exposure, we were able to measure several hundreds of atomic and molecular lines that are suitable for chemical abundance determinations. We also measured a prominent diffuse interstellar band at λ1317.8 nm (vacuum). This provides an independent reddening estimate.
Results. The radial velocities, Gaia proper motions, and extinction of seven red supergiants in Alicante 7 and three in Alicante 10 are consistent with them being members of the associations. One star toward Alicante 10 has kinematics and low extinction that are inconsistent with a membership. By means of spectral synthesis and line equivalent width measurements, we obtained chemical abundances for iron-peak, CNO, alpha, other light, and a few neutron-capture elements. We found average slightly subsolar iron abundances and solar-scaled [X/Fe] abundance patterns for most of the elements, consistent with a thin-disk chemistry. We found depletion of [C/Fe], enhancement of [N/Fe], and relatively low 12C/13C < 15, which is consistent with CN cycled material and possibly some additional mixing in their atmospheres.
Key words: supergiants / stars: abundances / infrared: stars
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 2019
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