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Gaia-ESO Survey: Analysis of pre-main sequence stellar spectra

Lanzafame, A. C.; Frasca, A.; Damiani, F.; Franciosini, E.; Cottaar, M.; Sousa, S. G.; Tabernero, H. M.; Klutsch, A.; Spina, L. and Biazzo, K., et al. (2015) In Astronomy & Astrophysics 576.
Abstract
Context. The Gaia-ESO Public Spectroscopic Survey is obtaining high-quality spectroscopy of some 100 000 Milky Way stars using the FLAMES spectrograph at the VLT, down to V = 19 mag, systematically covering all the main components of the Milky Way and providing the first homogeneous overview of the distributions of kinematics and chemical element abundances in the Galaxy. Observations of young open clusters, in particular, are giving new insights into their initial structure, kinematics, and their subsequent evolution. Aims. This paper describes the analysis of UVES and GIRAFFE spectra acquired in the fields of young clusters whose population includes pre-main sequence (PMS) stars. The analysis is applied to all stars in such fields,... (More)
Context. The Gaia-ESO Public Spectroscopic Survey is obtaining high-quality spectroscopy of some 100 000 Milky Way stars using the FLAMES spectrograph at the VLT, down to V = 19 mag, systematically covering all the main components of the Milky Way and providing the first homogeneous overview of the distributions of kinematics and chemical element abundances in the Galaxy. Observations of young open clusters, in particular, are giving new insights into their initial structure, kinematics, and their subsequent evolution. Aims. This paper describes the analysis of UVES and GIRAFFE spectra acquired in the fields of young clusters whose population includes pre-main sequence (PMS) stars. The analysis is applied to all stars in such fields, regardless of any prior information on membership, and provides fundamental stellar atmospheric parameters, elemental abundances, and PMS-specific parameters such as veiling, accretion, and chromospheric activity. Methods. When feasible,different methods were used to derive raw parameters (e. g. line equivalent widths) fundamental atmospheric parameters and derived parameters (e. g. abundances). To derive some of these parameters, we used methods that have been extensively used in the past and new ones developed in the context of the Gaia-ESO survey enterprise. The internal precision of these quantities was estimated by inter-comparing the results obtained by these different methods, while the accuracy was estimated by comparison with independent external data, such as effective temperature and surface gravity derived from angular diameter measurements, on a sample of benchmarks stars. A validation procedure based on these comparisons was applied to discard spurious or doubtful results and produce recommended parameters. Specific strategies were implemented to resolve problems of fast rotation, accretion signatures, chromospheric activity, and veiling. Results. The analysis carried out on spectra acquired in young cluster fields during the first 18 months of observations, up to June 2013, is presented in preparation of the first release of advanced data products. These include targets in the fields of the rho Oph, Cha I, NGC2264, gamma Vel, and NGC 2547 clusters. Stellar parameters obtained with the higher resolution and larger wavelength coverage from UVES are reproduced with comparable accuracy and precision using the smaller wavelength range and lower resolution of the GIRAFFE setup adopted for young stars, which allows us to provide stellar parameters with confidence for the much larger GIRAFFE sample. Precisions are estimated to be approximate to 120 K rms in T-eff, approximate to 0.3 dex rms in log g, and approximate to 0.15 dex rms in [Fe/H] for the UVES and GIRAFFE setups. (Less)
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open clusters and associations: general, surveys, methods: data, analysis, stars: pre-main sequence, stars: fundamental parameters
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Astronomy & Astrophysics
volume
576
publisher
EDP Sciences
external identifiers
  • wos:000357274600015
  • scopus:84926474514
ISSN
0004-6361
DOI
10.1051/0004-6361/201424759
language
English
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015f5c7c-8b11-4fb0-a6ac-a679a9192d34 (old id 7790488)
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2015-09-04 09:31:54
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@article{015f5c7c-8b11-4fb0-a6ac-a679a9192d34,
  abstract     = {Context. The Gaia-ESO Public Spectroscopic Survey is obtaining high-quality spectroscopy of some 100 000 Milky Way stars using the FLAMES spectrograph at the VLT, down to V = 19 mag, systematically covering all the main components of the Milky Way and providing the first homogeneous overview of the distributions of kinematics and chemical element abundances in the Galaxy. Observations of young open clusters, in particular, are giving new insights into their initial structure, kinematics, and their subsequent evolution. Aims. This paper describes the analysis of UVES and GIRAFFE spectra acquired in the fields of young clusters whose population includes pre-main sequence (PMS) stars. The analysis is applied to all stars in such fields, regardless of any prior information on membership, and provides fundamental stellar atmospheric parameters, elemental abundances, and PMS-specific parameters such as veiling, accretion, and chromospheric activity. Methods. When feasible,different methods were used to derive raw parameters (e. g. line equivalent widths) fundamental atmospheric parameters and derived parameters (e. g. abundances). To derive some of these parameters, we used methods that have been extensively used in the past and new ones developed in the context of the Gaia-ESO survey enterprise. The internal precision of these quantities was estimated by inter-comparing the results obtained by these different methods, while the accuracy was estimated by comparison with independent external data, such as effective temperature and surface gravity derived from angular diameter measurements, on a sample of benchmarks stars. A validation procedure based on these comparisons was applied to discard spurious or doubtful results and produce recommended parameters. Specific strategies were implemented to resolve problems of fast rotation, accretion signatures, chromospheric activity, and veiling. Results. The analysis carried out on spectra acquired in young cluster fields during the first 18 months of observations, up to June 2013, is presented in preparation of the first release of advanced data products. These include targets in the fields of the rho Oph, Cha I, NGC2264, gamma Vel, and NGC 2547 clusters. Stellar parameters obtained with the higher resolution and larger wavelength coverage from UVES are reproduced with comparable accuracy and precision using the smaller wavelength range and lower resolution of the GIRAFFE setup adopted for young stars, which allows us to provide stellar parameters with confidence for the much larger GIRAFFE sample. Precisions are estimated to be approximate to 120 K rms in T-eff, approximate to 0.3 dex rms in log g, and approximate to 0.15 dex rms in [Fe/H] for the UVES and GIRAFFE setups.},
  articleno    = {A80},
  author       = {Lanzafame, A. C. and Frasca, A. and Damiani, F. and Franciosini, E. and Cottaar, M. and Sousa, S. G. and Tabernero, H. M. and Klutsch, A. and Spina, L. and Biazzo, K. and Prisinzano, L. and Sacco, G. G. and Randich, S. and Brugaletta, E. and Delgado Mena, E. and Adibekyan, V. and Montes, D. and Bonito, R. and Gameiro, J. F. and Alcala, J. M. and Gonzalez Hernandez, J. I. and Jeffries, R. and Messina, S. and Meyer, M. and Gilmore, G. and Asplund, M. and Binney, J. and Bonifacio, P. and Drew, J. E. and Feltzing, Sofia and Ferguson, A. M. N. and Micela, G. and Negueruela, I. and Prusti, T. and Rix, H. -W. and Vallenari, A. and Alfaro, E. J. and Allende Prieto, C. and Babusiaux, C. and Bensby, Thomas and Blomme, R. and Bragaglia, A. and Flaccomio, E. and Francois, P. and Hambly, N. and Irwin, M. and Koposov, S. E. and Korn, A. J. and Smiljanic, R. and Van Eck, S. and Walton, N. and Bayo, A. and Bergemann, M. and Carraro, G. and Costado, M. T. and Edvardsson, B. and Heiter, U. and Hill, V. and Hourihane, A. and Jackson, R. J. and Jofre, P. and Lardo, C. and Lewis, J. and Lind, K. and Magrini, L. and Marconi, G. and Martayan, C. and Masseron, T. and Monaco, L. and Morbidelli, L. and Sbordone, L. and Worley, C. C. and Zaggia, S.},
  issn         = {0004-6361},
  keyword      = {open clusters and associations: general,surveys,methods: data,analysis,stars: pre-main sequence,stars: fundamental parameters},
  language     = {eng},
  publisher    = {EDP Sciences},
  series       = {Astronomy & Astrophysics},
  title        = {Gaia-ESO Survey: Analysis of pre-main sequence stellar spectra},
  url          = {http://dx.doi.org/10.1051/0004-6361/201424759},
  volume       = {576},
  year         = {2015},
}