J/A+A/561/A94 Velocities and photometry in Trumpler 20 (Donati+, 2014)
Gaia-ESO Survey: reevaluation of the parameters of the open cluster Trumpler 20
using photometry and spectroscopy.
Donati P., Gaudin Cantat , 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., Maiorca E.
<Astron. Astrophys. 561, A94 (2014)>
=2014A&A...561A..94D 2014A&A...561A..94D
ADC_Keywords: Clusters, open ; Photometry, UBV ; Radial velocities
Keywords: open clusters and associations: general -
Hertzsprung-Russell and C-M diagrams
Abstract:
Trumpler 20 is an old open cluster (OC) located toward the Galactic
centre, at about 3kpc from the Sun and ∼7kpc 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 the 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 1.35-1.66Gyr, an average reddening E(B-V) in the range
0.31-0.35mag, a distance modulus (m-M)0 between 12.64 and 12.72mag.
The spectroscopic metallicity is [Fe/H]=+0.17dex. 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.
Description:
We combined high quality photometry available in literature (Carraro
et al., 2010AJ....140..954C 2010AJ....140..954C, hereafter C10, and Platais et al., 2008,
Cat. J/MNRAS/391/1482, hereafter P08) and the spectroscopic
observations of the Gaia-ESO Survey to reevaluate the parameters of
the open cluster Trumpler 20.
1370 star spectra, taken with UVES and GIRAFFE spectrograph at
VLT/UT2, of both main sequence and red clump stars were exploited to
estimate the radial velocity distribution of the cluster stars and
select the most probable cluster members.
13 red clump stars observed with UVES were used to determine the
cluster metallicity.
With the improved information on metallicity and membership we used
the photometric catalogues to estimate age, distance and average
galactic reddening by means of the isochrone fitting method. We
estimated the differential reddening on the cluster face and found to
play a not negligible role on the CMD morphology.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 108 1370 Radial velocity table of GES targets
catalog.dat 135 14193 BVI photometry and differential reddening (DR)
corrections
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See also:
J/MNRAS/391/1482 : BVIc photometry of Trumpler 20 (Platais+, 2008)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- idC10 [1/15617]? Identification index of C10
catalogue (Carraro et al., 2010AJ....140..954C 2010AJ....140..954C)
7- 11 I5 --- idP08 [1/7202]? Identification index of P08 catalogue
(Platais et al. 2008, J/MNRAS/391/1482),
<Cl* Trumpler 20 PMF NNNN> in Simbad
13- 28 A16 --- idGES Identification index of the Gaia-ESO Survey
(HHMMSSss+DDMMSSs, ICRS)
30- 34 F5.2 mag Vmag V magnitude from C10 or P08
36- 40 F5.2 mag Bmag B magnitude from C10 or P08
42- 52 F11.7 deg RAdeg Right Ascension coordinate J2000
54- 64 F11.7 deg DEdeg Declination coordinate J2000
66- 72 F7.2 km/s RV1 ? Radial velocity from Giraffe-HR09b spectra
(514.3-535.6nm)
74- 79 F6.2 km/s e_RV1 ? Error on RV2
81- 87 F7.2 km/s RV2 ? Radial velocity from Giraffe-HR15n spectra
(476-684nm)
89- 94 F6.2 km/s e_RV2 ? Error on RV2
96-102 F7.2 km/s RV3 ? Radial velocity from UVES spectra (647-679nm)
104-108 F5.2 km/s e_RV3 ? Error on RV3
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Byte-by-byte Description of file: catalog.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- ID [1/14193]+ Identification index
8- 12 I5 --- idC10 [1/15617]?=99999 Identification index of C10
catalogue (Carraro et al., 2010AJ....140..954C 2010AJ....140..954C)
15- 19 I5 --- idP08 [1/7202]?=99999 Identification index of P08
catalogue (Platais et al. 2008, J/MNRAS/391/1482
<Cl* Trumpler 20 PMF NNNN> in Simbad
21- 28 F8.5 arcmin Dist Distance from the cluster centre
30- 40 F11.7 deg RAdeg Right Ascension coordinate J2000
42- 52 F11.7 deg DEdeg Declination coordinate J2000
55- 60 F6.3 mag Vmag1 ?=99.999 V magnitude from C10 catalogue
63- 68 F6.3 mag (B-V)1 ?=9.999 B-V colour index from C10 catalogue
75- 79 F5.3 mag (V-I)1 ?=9.999 V-I colour index from C10 catalogue
82- 87 F6.3 mag (U-V)1 ?=9.999 U-V colour index from C10 catalogue
90- 95 F6.3 mag Vmag2 ?=99.999 V magnitude from P08 catalogue
99-103 F5.3 mag (B-V)2 ?=9.999 B-V colour index from P08 catalogue
107-111 F5.3 mag (V-I)2 ?=9.999 V-I colour index from P08 catalogue
113-119 F7.3 mag E(B-V) ?=9.999 Differential reddening (DR) correction
in E(B-V)
122-127 F6.3 mag Vmag1c ?=99.999 Vmag1 (from C10) corrected for DR
130-135 F6.3 mag (B-V)1c ?=9.999 (B-V)1 (from C10) corrected for DR
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Acknowledgements:
Paolo Donati, paolo.donati4(at)unibo.it
(End) Paolo Donati [UNIBO, Italy], Patricia Vannier [CDS] 10-Dec-2013