V363 Cassiopeiae: a new lithium-rich Galactic Cepheid
Journal
Date Issued
2020
Abstract
Context. Classical Cepheids (DCEPs) are important astrophysical objects not only as standard candles in the determination of the cosmic distance ladder, but also as a testbed for the stellar evolution theory. This is based on the strict connection between their pulsation (period(s) and amplitudes) and stellar parameters (luminosity, mass, effective temperature, and metallicity).
Aims: We examine the nature of the Galactic DCEP V363 Cas and other DCEPs that show cosmic abundances of lithium in their atmospheres.
Methods: We collected three epochs of high-resolution spectroscopy for V363 Cas with HARPS-N at the TNG. We measured accurate stellar parameters: the effective temperatures, gravities, microturbulences, radial velocities, and metal abundances.
Results: We detected a lithium abundance of A(Li) = 2.86 ± 0.10 dex, along with iron, carbon, and oxygen abundances of [Fe/H] = -0.30 ± 0.12 dex, [C/H] = -0.06 ± 0.15 dex, and [O/H] = 0.00 ± 0.12 dex. V363 Cas is the fifth of the Milky Way DCEPs to exhibit a Li-rich feature. An analysis of historical time-series spanning a 100-year interval shows that the period of V363 Cas is increasing, with a sharp acceleration after HJD = 2 453 000 days. This is a clear indication of a first crossing of the instability strip.
Conclusions: Our results favour the scenario in which the five Galactic Li-rich DCEPs are on their first crossing of the instability strip and have had slowly rotating progenitors during their main-sequence phase.
Aims: We examine the nature of the Galactic DCEP V363 Cas and other DCEPs that show cosmic abundances of lithium in their atmospheres.
Methods: We collected three epochs of high-resolution spectroscopy for V363 Cas with HARPS-N at the TNG. We measured accurate stellar parameters: the effective temperatures, gravities, microturbulences, radial velocities, and metal abundances.
Results: We detected a lithium abundance of A(Li) = 2.86 ± 0.10 dex, along with iron, carbon, and oxygen abundances of [Fe/H] = -0.30 ± 0.12 dex, [C/H] = -0.06 ± 0.15 dex, and [O/H] = 0.00 ± 0.12 dex. V363 Cas is the fifth of the Milky Way DCEPs to exhibit a Li-rich feature. An analysis of historical time-series spanning a 100-year interval shows that the period of V363 Cas is increasing, with a sharp acceleration after HJD = 2 453 000 days. This is a clear indication of a first crossing of the instability strip.
Conclusions: Our results favour the scenario in which the five Galactic Li-rich DCEPs are on their first crossing of the instability strip and have had slowly rotating progenitors during their main-sequence phase.
Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated by the Fundación Galileo Galilei (FGG) of the Istituto Nazionale di Astrofisica (INAF) at the Observatorio del Roque de los Muchachos (La Palma, Canary Islands, Spain).
Volume
639
Start page
L4
Issn Identifier
0004-6361
Ads BibCode
2020A&A...639L...4C
Rights
open.access
File(s)![Thumbnail Image]()
Loading...
Name
aa38486-20.pdf
Description
Pdf editoriale
Size
690.16 KB
Format
Adobe PDF
Checksum (MD5)
ea4c7913f0f8885ba1d8a8ab429ae4e6