J/A+A/573/A55 Gaia-ESO Survey: Tr 20, NGC4815, NGC6705 (Tautvaisiene+, 2015) ================================================================================ The Gaia-ESO Survey: CNO abundances in the open clusters Trumpler 20, NGC 4815, and NGC 6705. Tautvaisiene G., Drazdauskas A., Mikolaitis S., Barisevicius G., Puzeras E., Stonkute E., Chorniy Y., Magrini L., Romano D., Smiljanic R., Bragaglia A., Carraro G., Friel E., Morel T., Pancino E., Donati P., Jimenez-Esteban F., Gilmore G., Randich S., Jeffries R.D., Vallenari A., Bensby T., Flaccomio E., Recio-Blanco A., Costado M.T., Hill V., Jofre P., Lardo C., De Laverny P., Masseron T., Moribelli L., Sousa S.G., Zaggia S. =2015A&A...573A..55T (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Clusters, open ; Radial velocities ; Rotational velocities Keywords: 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 Abstract: 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. 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. 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{AA}. The wavelength interval 6470-6490{AA}, with CN features, was analysed to determine nitrogen abundances. Oxygen abundances were determined from the [OI] line at 6300{AA}. 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 NGC 4815: [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 NGC 6705: [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 3.3M_{sun}_, 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 NGC 4815 and NGC 6705 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. 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. Description: Observations were conducted with the FLAMES (Fiber Large Array Multi-Element Spectrograph) multi-fiber facility in spring of 2012 and 2013. Spectra of high-resolving power (R~47000) were obtained with UVES (Ultraviolet and Visual Echelle Spectrograph) The spectra were exposed onto two CCDs, resulting in a wavelength coverage of 4700-6840{AA} with a gap of about 50{AA} in the centre. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 81 42 Stellar parameters for target stars in Trumpler 20 table2.dat 81 5 Stellar parameters for target stars in NGC 4815 table3.dat 81 27 Stellar parameters for target stars in NGC 6705 table5.dat 60 42 Main atmospheric parameters and elemental abundances for stars in the open cluster Trumpler 20 table6.dat 60 5 Main atmospheric parameters and elemental abundances for stars in the open cluster NGC 4815 table7.dat 60 27 Main atmospheric parameters and elemental abundances for stars in the open cluster NGC 6705 -------------------------------------------------------------------------------- See also: J/MNRAS/310/982 : UBVI CCD Photometry of M11 - II. (Sung+ 1999) Byte-by-byte Description of file: table1.dat table2.dat table3.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1 I1 --- Ref [1/3] Reference (1) 3- 6 I4 --- ID Identification number from reference 8- 23 A16 --- GES GES ID (HHMMSSss+DDMMSSs), GES JHHMMSSss+DDMMSSs in Simbad 25- 32 F8.4 deg RAdeg Right ascension (J2000) 34- 41 F8.4 deg DEdeg Declination (J2000) 43- 48 F6.3 mag Vmag V magnitude 50- 54 F5.3 mag B-V ? B-V colour index 56- 60 F5.3 mag V-I ? V-I colour index 62- 67 F6.2 km/s RV Radial velocity 69- 71 I3 --- S/N Signal-to-noise ratio 73- 76 F4.2 km/s vinsiG GES database value of rotational velocity 78- 81 F4.1 km/s vsini Rotational velocity determined in this work -------------------------------------------------------------------------------- Note (1): References as follows: 1 = ID and photometric data were taken from Carraro et al. (2010AJ....140..954C) 2 = V and V-I were taken from Prisinzano et al. (2001A&A...369..851P) 3 = ID and photometric data were taken from Sung et al. (1999, Cat. J/MNRAS/310/982, Cl* NGC 6705 SBL NNNNNN in Simbad) -------------------------------------------------------------------------------- Byte-by-byte Description of file: table5.dat table6.dat table7.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 16 A16 --- GES GES designation 17 A1 --- n_GES [*] Note on GES (1) 19- 22 I4 K Teff Effective temperature 24- 27 F4.2 [cm/s2] logg Surface gravity 29- 32 F4.2 km/s vt Microturbulent velocity 34- 38 F5.2 [-] [Fe/H] Metallicity (2) 40- 44 F5.2 [-] [C/H] Abundance [C/H] (2) 46- 49 F4.2 [-] [N/H] ? Abundance [N/H] (2) 51- 55 F5.2 [-] [O/H] ? Abundance [O/H] (2) 57- 60 F4.2 --- C/N ? Abundance C/N (2) -------------------------------------------------------------------------------- Note (1): *: This star is a subgiant located close to the main sequence turn-off and had no CN bands strong enough for the nitrogen abundance determination. Note (2): Mean values: Trumpler 20 NGC 4815 NGC 6705 --------------------------------------------------------------------- [Fe/H] 0.10+/-0.08 -0.01+/-0.04 0.00+/-0.05 [C/H] -0.10+/-0.10 -0.17+/-0.08 -0.08+/-0.06 [N/H] 0.50+/-0.07 0.53+/-0.07 0.61+/-0.07 [O/H] 0.12+/-0.09 0.13+/-0.05 C/N 0.98+/-0.12 0.79+/-0.08 0.83+/-0.19 --------------------------------------------------------------------- -------------------------------------------------------------------------------- History: * 15-Jan-2016: From electronic version of the journal, tables 1-3 * 13-Jun-2016: tables 5-7 added ================================================================================ (End) Patricia Vannier [CDS] 14-Dec-2015