Webbläsaren som du använder stöds inte av denna webbplats. Alla versioner av Internet Explorer stöds inte längre, av oss eller Microsoft (läs mer här: * https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Var god och använd en modern webbläsare för att ta del av denna webbplats, som t.ex. nyaste versioner av Edge, Chrome, Firefox eller Safari osv.

The Gaia-ESO Survey: CNO abundances in the open clusters Trumpler 20, NGC 4815, and NGC 6705

In English

Författare

  • G. Tautvaisiene
  • A. Drazdauskas
  • S. Mikolaitis
  • G. Barisevicius
  • E. Puzeras
  • E. Stonkute
  • Y. Chorniy
  • L. Magrini
  • D. Romano
  • R. Smiljanic
  • A. Bragaglia
  • G. Carraro
  • E. Friel
  • T. Morel
  • E. Pancino
  • P. Donati
  • F. Jimenez-Esteban
  • G. Gilmore
  • S. Randich
  • R. D. Jeffries
  • A. Vallenari
  • Thomas Bensby
  • E. Flaccomio
  • A. Recio-Blanco
  • M. T. Costado
  • V. Hill
  • P. Jofre
  • C. Lardo
  • P. de laverny
  • T. Masseron
  • L. Moribelli
  • S. G. Sousa
  • S. Zaggia
Visa allt

Summary, in English

Context. The Gaia-ESO Public Spectroscopic Survey will observe a large sample of clusters and cluster stars, covering a wide age-distance-metallicity-position-density parameter space. Aims. We aim to determine C, N, and O abundances in stars of Galactic open clusters of the Gaia-ESO survey and to compare the observed abundances with those predicted by current stellar and Galactic evolution models. In this pilot paper, we investigate the first three intermediate-age open clusters. Methods. High-resolution spectra, observed with the FLAMES-UVES spectrograph on the ESO VLT, were analysed using a differential model atmosphere method. Abundances of carbon were derived using the C-2 band heads at 5135 and 5635.5 angstrom. The wavelength interval 6470-6490 angstrom, with CN features, was analysed to determine nitrogen abundances. Oxygen abundances were determined from the [O I] line at 6300 angstrom. Results. The mean values of the elemental abundances in Trumpler 20 as determined from 42 stars are: [Fe/H] = 0.10 +/- 0.08 (s.d.), [C/H] = -0.10 +/- 0.07, [N/H] = 0.50 +/- 0.07, and consequently C = N = 0.98 +/- 0.12. We measure from five giants in NGC4815: [Fe/H] = 0.01 +/- 0.04, [C/H] = -0.17 +/- 0.08, [N/H] = 0.53 +/- 0.07, [O/H] = 0.12 +/- 0.09, and C/N = 0.79 +/- 0.08. We obtain from 27 giants in NGC6705: [Fe/H] = 0.0 +/- 0.05, [C/H] = 0.08 +/- 0.06, [N/H] = 0.61 +/- 0.07, [O/H] = 0.13 +/- 0.05, and C/N = 0.83 +/- 0.19. The C/N ratios of stars in the investigated open clusters were compared with the ratios predicted by stellar evolutionary models. For the corresponding stellar turn-off masses from 1.9 to 3.3 M-circle dot, the observed C/N ratio values are very close to the predictions of standard first dredge-up models as well as to models of thermohaline extra-mixing. They are not decreased as much as predicted by the recent model in which the thermohaline-and rotation-induced extra-mixing act together. The average [O/H] abundance ratios of NGC4815 and NGC6705 are compared with the predictions of two Galactic chemical evolution models. The data are consistent with the evolution at the solar radius within the errors. Conclusions. The first results of CNO determinations in open clusters show the potential of the Gaia-ESO Survey to judge stellar and Galactic chemical evolution models and the validity of their physical assumptions through a homogeneous and detailed spectral analysis.

Publiceringsår

2015

Språk

Engelska

Publikation/Tidskrift/Serie

Astronomy & Astrophysics

Volym

573

Dokumenttyp

Artikel i tidskrift

Förlag

EDP Sciences

Ämne

  • Astronomy, Astrophysics and Cosmology

Nyckelord

  • stars: abundances
  • stars: evolution
  • Galaxy: evolution
  • open clusters
  • and associations: individual: Trumpler 20
  • open clusters and
  • associations: individual: NGC4815
  • open clusters and associations:
  • individual: NGC6705

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0004-6361