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The Gaia -ESO Survey : A new approach to chemically characterising young open clusters: I. Stellar parameters, and iron-peak, α -, and proton-capture elements

Baratella, M. ; D'Orazi, V. ; Carraro, G. ; Desidera, S. ; Randich, S. ; Magrini, L. ; Adibekyan, V. ; Smiljanic, R. ; Spina, L. and Tsantaki, M. , et al. (2020) In Astronomy and Astrophysics 634.
Abstract

Context. Open clusters are recognised as excellent tracers of Galactic thin-disc properties. At variance with intermediate-age and old open clusters, for which a significant number of studies is now available, clusters younger than ≲ 150 Myr have been mostly overlooked in terms of their chemical composition until recently (with few exceptions). On the other hand, previous investigations seem to indicate an anomalous behaviour of young clusters, which includes (but is not limited to) slightly sub-solar iron (Fe) abundances and extreme, unexpectedly high barium (Ba) enhancements. Aims. In a series of papers, we plan to expand our understanding of this topic and investigate whether these chemical peculiarities are instead related to... (More)

Context. Open clusters are recognised as excellent tracers of Galactic thin-disc properties. At variance with intermediate-age and old open clusters, for which a significant number of studies is now available, clusters younger than ≲ 150 Myr have been mostly overlooked in terms of their chemical composition until recently (with few exceptions). On the other hand, previous investigations seem to indicate an anomalous behaviour of young clusters, which includes (but is not limited to) slightly sub-solar iron (Fe) abundances and extreme, unexpectedly high barium (Ba) enhancements. Aims. In a series of papers, we plan to expand our understanding of this topic and investigate whether these chemical peculiarities are instead related to abundance analysis techniques. Methods. We present a new determination of the atmospheric parameters for 23 dwarf stars observed by the Gaia-ESO survey in five young open clusters (τ < 150 Myr) and one star-forming region (NGC 2264). We exploit a new method based on titanium (Ti) lines to derive the spectroscopic surface gravity, and most importantly, the microturbulence parameter. A combination of Ti and Fe lines is used to obtain effective temperatures. We also infer the abundances of Fe » I, Fe » II, Ti » I, Ti » II, Na » I, Mg » I, Al » I, Si » I, Ca » I, Cr » I, and Ni » I. Results. Our findings are in fair agreement with Gaia-ESO iDR5 results for effective temperatures and surface gravities, but suggest that for very young stars, the microturbulence parameter is over-estimated when Fe lines are employed. This affects the derived chemical composition and causes the metal content of very young clusters to be under-estimated. Conclusions. Our clusters display a metallicity [Fe/H] between +0.04 ± 0.01 and +0.12 ± 0.02; they are not more metal poor than the Sun. Although based on a relatively small sample size, our explorative study suggests that we may not need to call for ad hoc explanations to reconcile the chemical composition of young open clusters with Galactic chemical evolution models.

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type
Contribution to journal
publication status
published
subject
keywords
Open clusters and associations: general, Stars: abundances, Stars: fundamental parameters, Stars: solar-type
in
Astronomy and Astrophysics
volume
634
article number
A34
publisher
EDP Sciences
external identifiers
  • scopus:85086566772
ISSN
0004-6361
DOI
10.1051/0004-6361/201937055
project
Gaia-ESO Survey
language
English
LU publication?
yes
id
8cef80a4-ce15-4327-852f-e398dd172272
date added to LUP
2021-01-07 10:53:29
date last changed
2024-03-05 17:05:13
@article{8cef80a4-ce15-4327-852f-e398dd172272,
  abstract     = {{<p>Context. Open clusters are recognised as excellent tracers of Galactic thin-disc properties. At variance with intermediate-age and old open clusters, for which a significant number of studies is now available, clusters younger than ≲ 150 Myr have been mostly overlooked in terms of their chemical composition until recently (with few exceptions). On the other hand, previous investigations seem to indicate an anomalous behaviour of young clusters, which includes (but is not limited to) slightly sub-solar iron (Fe) abundances and extreme, unexpectedly high barium (Ba) enhancements. Aims. In a series of papers, we plan to expand our understanding of this topic and investigate whether these chemical peculiarities are instead related to abundance analysis techniques. Methods. We present a new determination of the atmospheric parameters for 23 dwarf stars observed by the Gaia-ESO survey in five young open clusters (τ &lt; 150 Myr) and one star-forming region (NGC 2264). We exploit a new method based on titanium (Ti) lines to derive the spectroscopic surface gravity, and most importantly, the microturbulence parameter. A combination of Ti and Fe lines is used to obtain effective temperatures. We also infer the abundances of Fe » I, Fe » II, Ti » I, Ti » II, Na » I, Mg » I, Al » I, Si » I, Ca » I, Cr » I, and Ni » I. Results. Our findings are in fair agreement with Gaia-ESO iDR5 results for effective temperatures and surface gravities, but suggest that for very young stars, the microturbulence parameter is over-estimated when Fe lines are employed. This affects the derived chemical composition and causes the metal content of very young clusters to be under-estimated. Conclusions. Our clusters display a metallicity [Fe/H] between +0.04 ± 0.01 and +0.12 ± 0.02; they are not more metal poor than the Sun. Although based on a relatively small sample size, our explorative study suggests that we may not need to call for ad hoc explanations to reconcile the chemical composition of young open clusters with Galactic chemical evolution models.</p>}},
  author       = {{Baratella, M. and D'Orazi, V. and Carraro, G. and Desidera, S. and Randich, S. and Magrini, L. and Adibekyan, V. and Smiljanic, R. and Spina, L. and Tsantaki, M. and Tautvaišienė, G. and Sousa, S. G. and Jofré, P. and Jiménez-Esteban, F. M. and Delgado-Mena, E. and Martell, S. and Van Der Swaelmen, M. and Roccatagliata, V. and Gilmore, G. and Alfaro, E. J. and Bayo, A. and Bensby, T. and Bragaglia, A. and Franciosini, E. and Gonneau, A. and Heiter, U. and Hourihane, A. and Jeffries, R. D. and Koposov, S. E. and Morbidelli, L. and Prisinzano, L. and Sacco, G. and Sbordone, L. and Worley, C. and Zaggia, S. and Lewis, J.}},
  issn         = {{0004-6361}},
  keywords     = {{Open clusters and associations: general; Stars: abundances; Stars: fundamental parameters; Stars: solar-type}},
  language     = {{eng}},
  publisher    = {{EDP Sciences}},
  series       = {{Astronomy and Astrophysics}},
  title        = {{The Gaia -ESO Survey : A new approach to chemically characterising young open clusters: I. Stellar parameters, and iron-peak, α -, and proton-capture elements}},
  url          = {{http://dx.doi.org/10.1051/0004-6361/201937055}},
  doi          = {{10.1051/0004-6361/201937055}},
  volume       = {{634}},
  year         = {{2020}},
}