2014A&A...563A.117F


C.D.S. - SIMBAD4 rel 1.7 - 2019.12.12CET02:16:34

2014A&A...563A.117F - Astronomy and Astrophysics, volume 563A, 117-117 (2014/3-1)

Gaia-ESO Survey: Properties of the intermediate age open cluster NGC 4815.

FRIEL E.D., DONATI P., BRAGAGLIA A., JACOBSON H.R., MAGRINI L., PRISINZANO L., RANDICH S., TOSI M., CANTAT-GAUDIN T., VALLENARI A., SMILJANIC R., CARRARO G., SORDO R., MAIORCA E., TAUTVAISIENE G., SESTITO P., ZAGGIA S., JIMENEZ-ESTEBAN F.M., GILMORE G., JEFFRIES R.D., ALFARO E., BENSBY T., KOPOSOV S.E., KORN A.J., PANCINO E., RECIO-BLANCO A., FRANCIOSINI E., HILL V., JACKSON R.J., DE LAVERNY P., MORBIDELLI L., SACCO G.G., WORLEY C.C., HOURIHANE A., COSTADO M.T., JOFRE P. and LIND K.

Abstract (from CDS):

NGC 4815 is a populous ∼500Myr open cluster at Rgc∼7kpc observed in the first six months of the Gaia-ESO Survey. Located in the inner Galactic disk, NGC 4815 is an important potential tracer of the abundance gradient, where relatively few intermediate age open clusters are found. The Gaia-ESO Survey data can provide an improved characterization of the cluster properties, such as age, distance, reddening, and abundance profile. We use the survey derived radial velocities, stellar atmospheric parameters, metallicity, and elemental abundances for stars targeted as potential members of this cluster to carry out an analysis of cluster properties. The radial velocity distribution of stars in the cluster field is used to define the cluster systemic velocity and derive likely cluster membership for stars observed by the Gaia-ESO Survey. We investigate the distributions of Fe and Fe-peak elements, alpha-elements, and the light elements Na and Al and characterize the cluster's internal chemical homogeneity comparing it to the properties of radial velocity non-member stars. Utilizing these cluster properties, the cluster color-magnitude diagram is analyzed and theoretical isochrones are fit to derive cluster reddening, distance, and age. NGC 4815 is found to have a mean metallicity of [Fe/H]=+0.03±0.05dex (s.d.). Elemental abundances of cluster members show typically very small internal variation, with internal dispersions of ∼0.05dex. The alpha-elements [Ca/Fe] and [Si/Fe] show solar ratios, but [Mg/Fe] is moderately enhanced, while [Ti/Fe] appears slightly deficient. As with many open clusters, the light elements [Na/Fe] and [Al/Fe] are enhanced, [Na/Fe] significantly so, although the role of internal mixing and the assumption of local thermodynamical equilibrium in the analysis remain to be investigated. From isochrone fits to color-magnitude diagrams, we find a cluster age of 0.5 to 0.63Gyr, a reddening of E(B-V)=0.59 to 0.65, and a distance modulus (m-M)0=11.95 to 12.20, depending on the choice of theoretical models, leading to a Galactocentric distance of 6.9kpc.

Abstract Copyright:

Journal keyword(s): open clusters and associations: individual: NGC 4815 - stars: abundances - Hertzsprung-Russell and C-M diagrams

Simbad objects: 23

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Number of rows : 23

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 Cl Melotte 25 OpC 04 26 54.00 +15 52 00.0           ~ 2588 0
2 Ass Vel OB 2 As* 08 09 22.478 -47 21 03.46           ~ 200 0
3 Cl Collinder 261 OpC 12 38 11.5 -68 22 01     10.7     ~ 152 0
4 Cl Trumpler 20 OpC 12 39 45 -60 38.1     10.1     ~ 68 0
5 GES J12571312-6456090 * 12 57 13.12007 -64 56 08.9990   16.482 14.811     ~ 2 0
6 GES J12572442-6455173 * 12 57 24.42 -64 55 17.3   15.373 13.482   11.209 ~ 5 0
7 GES J12573217-6455167 * 12 57 32.17007 -64 55 16.7020   15.799 14.190   12.370 ~ 2 0
8 GES J12574080-6455572 * 12 57 40.80000 -64 55 57.2000   15.681 14.186   12.417 ~ 1 0
9 GES J12574328-6457386 * 12 57 43.28 -64 57 38.6   15.405 13.703   11.757 ~ 5 0
10 GES J12574341-6458045 * 12 57 43.41000 -64 58 04.5010   16.108 14.564   12.759 ~ 2 0
11 GES J12574457-6459398 * 12 57 44.56993 -64 59 39.8000   15.795 14.376   12.795 ~ 2 0
12 GES J12574905-6458511 * 12 57 49.05000 -64 58 51.1000     14.709   12.926 ~ 3 0
13 GES J12575308-6457182 * 12 57 53.08007 -64 57 18.2020   15.812 14.429   12.666 ~ 2 0
14 GES J12575511-6458483 * 12 57 55.11 -64 58 48.3   15.692 14.043   12.202 ~ 6 0
15 GES J12575529-6456536 * 12 57 55.29 -64 56 53.6   15.718 14.128   12.398 ~ 6 0
16 GES J12575531-6500412 * 12 57 55.30993 -65 00 41.1980     14.015   12.474 ~ 2 0
17 NGC 4815 OpC 12 58 01 -64 57.6   9.61 8.6     ~ 66 0
18 GES J12580262-6456492 * 12 58 02.62 -64 56 49.2   15.771 14.158   12.262 ~ 6 0
19 GES J12581939-6453533 * 12 58 19.39001 -64 53 53.3000   17.184 14.874   13.214 ~ 2 0
20 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11083 0
21 NGC 6705 OpC 18 51 05 -06 16.2   6.32 5.8     ~ 350 0
22 NAME Sgr Arm PoG 19 00 -30.0           ~ 496 1
23 NGC 6791 OpC 19 20 53 +37 46.3   10.52 9.5     ~ 847 0

    Equat.    Gal    SGal    Ecl

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2019.12.12-02:16:34

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