51. The Gaia-ESO Survey: Reevaluation of the parameters of the open cluster Trumpler 20 using photometry and spectroscopy
- Author
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Maiorca, E., Lardo, C., Jofre, P., Hourihane, A., Worley, C., Sacco, G., Prisinzano, L., Morbidelli, L., Lewis, J., De Laverny, P., Franciosini, E., Recio-Blanco, A., Pancino, E., Korn, A., Koposov, S., Flaccomio, E., Bensby, T., Randich, S., Gilmore, G., Zaggia, S., Roman, I., Muñoz, C., Mowlavi, N., Klutsch, A., Geisler, D., Costado, M., Blanco-Cuaresma, S., Tautvaišienė, G., Sordo, R., Tosi, M., Vallenari, A., Smiljanic, R., Magrini, L., Friel, E., Bragaglia, A., Cantat-Gaudin, T., Donati, P., Jofré, P., M2A 2014, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB), Department of Astronomy and Space Physics [Uppsala], Uppsala University, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1, Donati P., Cantat Gaudin T., Bragaglia A., Friel E., Magrini L., Smiljanic R., Vallenari A., Tosi M., Sordo R., Tautvaisiene G., Blanco-Cuaresma S., Costado M.T., Geisler D., Klutsch A., Mowlavi N., Munoz C., San Roman I., Zaggia S., Gilmore G., Randich S., Bensby T., Flaccomio E., Koposov S.E., Korn A.J., Pancino E., Recio-Blanco A., Franciosini E., De Laverny P., Lewis J., Morbidelli L., Prisinzano L., Sacco G., Worley C.C., Hourihane A., Jofre P., Lardo C., and Maiorca E.
- Subjects
Physics ,Line-of-sight ,Spiral galaxy ,astro-ph.SR ,[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR] ,Metallicity ,FOS: Physical sciences ,Astronomy and Astrophysics ,Open clusters and associations: general ,Astrophysics ,[PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR] ,Photometry (optics) ,Stars ,Distance modulus ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Hertzsprung-Russell and C-M diagram ,10. No inequality ,Red clump ,Solar and Stellar Astrophysics (astro-ph.SR) ,Open cluster - Abstract
Trumpler 20 is an old open cluster (OC) located toward the Galactic centre, at about 3 kpc from the Sun and $\sim$7 kpc from the Galactic centre. Its position makes this cluster particularly interesting in the framework of the chemical properties of the Galactic disc because very few old OCs reside in the inner part of the disc. For this reason it has been selected as a cluster target of the Gaia-ESO Survey, and spectra of many stars in the main sequence and red clump phases are now available. Moreover, although it has been studied by several authors in the past, no consensus on the evolutionary status of Tr 20 has been reached. The heavy contamination of field stars (the line of sight of Tr 20 crosses the Carina spiral arm) complicates a correct interpretation. Another interesting aspect of the cluster is that it shows a broadened main-sequence turn-off and a prominent and extended red-clump, characteristics that are not easily explained by classical evolutionary models. Exploiting both spectroscopic information from the Gaia-ESO Survey (and the ESO archive) and literature photometry, we obtain a detailed and accurate analysis of the properties of the cluster. We make use of the first accurate metallicity measurement ever obtained from several spectra of red clump stars, and of cluster membership determination using radial velocities. According to the evolutionary models adopted, we find that Tr 20 has an age in the range 1.35-1.66 Gyr, an average reddening $E(B-V)$ in the range 0.31-0.35 mag, and a distance modulus $(m-M)_0$ between 12.64 and 12.72 mag. The spectroscopic metallicity is [Fe/H]=+0.17 dex. We discuss the structural properties of the object and constrain possible hypotheses for its broadened upper main sequence by estimating the effect of differential reddening and its extended red clump., 14 pages, 14 figures - Accepted on 9 Dec. 2013 Reference list updated and minor corrections added to the text
- Published
- 2014