J/A+A/588/A120 Equivalent widths in 10 open clusters (Cantat-Gaudin+, 2016)
Abundances and kinematics for ten anticentre open clusters. Cantat-Gaudin T., Donati P., Vallenari A., Sordo R., Bragaglia A., Magrini L. <Astron. Astrophys. 588, A120 (2016)> =2016A&A...588A.120C (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Clusters, open ; Equivalent widths Keywords: stars: abundances - Galaxy: disk - open clusters and associations, general Abstract: Open clusters are distributed all across the disk and are convenient tracers of its properties. In particular, outer disk clusters bear a key role for the investigation of the chemical evolution of the Galactic disk. The goal of this study is to derive homogeneous elemental abundances for a sample of ten outer disk OCs, and investigate possible links with disk structures such as the Galactic Anticenter Stellar Structure. We analyse high-resolution spectra of red giants, obtained from the HIRES@Keck and UVES@VLT archives. We derive elemental abundances and stellar atmosphere parameters by means of the classical equivalent width method. We also performed orbit integrations using proper motions. The Fe abundances we derive trace a shallow negative radial metallicity gradient of slope -0.027±0.007dex/kpc in the outer 12kpc of the disk. The [alpha/Fe] gradient appears flat, with a slope of 0.006±0.007dex/kpc. The two outermost clusters (Be 29 and Sau 1) appear to follow elliptical orbits. Be 20 also exhibits a peculiar orbit with a large excursion above the plane. The irregular orbits of the three most metal-poor clusters (two of which are located at the edge of the Galactic disk), if confirmed by more robust astrometric measurements such as those of the Gaia mission, are compatible with an inside-out formation scenario for the Milky Way, in which extragalactic material is accreted onto the outer disk. We cannot determine if Be 20, Be 29, and Sau 1 are of extragalactic origin, as they may be old genuine Galactic clusters whose orbits were perturbed by accretion events or minor mergers in the past 5Gyr, or they may be representants of the thick disk population. The nature of these objects is intriguing and deserves further investigations in the near future. Description: Measured equivalent widths for spectra of 44 stars in 10 open clusters. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 86 10 Summary of main parameters for the ten clusters under study table2.dat 103 44 Summary of observations for 44 stars observed in ten clusters table.dat 50 17263 Equivalent widths
See also: J/A+AS/108/151 : Open clusters CCD photometry. I. (Kaluzny, 1994) J/MNRAS/346/18 : VIc photometry in Saurer A, B and C (Carraro+, 2003) J/MNRAS/360/655 : BVI photometry of 3 open clusters (Carraro+, 2005) J/A+A/442/917 : BVI photometry in Berkeley 73, 75 and 25 (Carraro+, 2005) J/A+A/488/943 : Abundances of giants in 4 Galactic clusters (Sestito+, 2008) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 4 A4 --- Cluster Cluster name 6- 12 F7.3 deg RAdeg Right ascension (J2000) 14- 20 F7.3 deg DEdeg Declination (J2000) 22- 28 F7.3 deg GLON Galactic longitude 30- 36 F7.3 deg GLAT Galactic latitude 38- 41 F4.1 kpc Dsun Heliocentric distance 43- 46 F4.1 kpc RGC Galactocentric distance (1) 48- 51 F4.1 kpc Z Heigth above the plane 53- 57 F5.2 [-] [Fe/H] Metallicity (2) 59- 62 F4.2 [-] e_[Fe/H] rms uncertainty on [Fe/H] 64- 68 F5.2 [-] [alpha/Fe] Abundance [alpha/Fe] (2) 70- 73 F4.2 [-] e_[alpha/Fe] rms uncertainty on [alpha/Fe] 76 I1 --- NMemb Number of members 77 A1 --- --- [/] 78 I1 --- Ntarg Number of targets 80- 82 F3.1 Gyr Age Age 84- 86 A3 --- r_Age Reference for Age (3)
Note (1): computed using the literature value for d and RGC☉=8.3kpc. Note (2): [Fe/H] and [alpha/Fe] values are those derived in Sect. 4.1 of this study. Note (3): References as follows: C04 = Carraro et al., 2004AJ....128.1676C V05 = Villanova et al., 2005, Cat. J/AJ/130/652 C07 = Carraro et al., 2007, Cat. J/A+A/476/217 A11 = Andreuzzi et al., 2011, Cat. J/MNRAS/412/1265 F08 = Frinchaboy et al., 2008MNRAS.391...39F
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 4 A4 --- Cluster Cluster name 6- 12 A7 --- Star Star name (1) 14- 15 I2 h RAh Star right ascension (J2000) 17- 18 I2 min RAm Star right ascension (J2000) 20- 25 F6.3 s RAs Star right ascension (J2000) 27 A1 --- DE- Star declination sign (J2000) 28- 29 I2 deg DEd Star declination (J2000) 31- 32 I2 arcmin DEm Star declination (J2000) 34- 38 F5.2 arcsec DEs Star declination (J2000) 40- 45 F6.3 mag Vmag V magnitude 47- 51 F5.3 mag V-I V-I colour index 54- 63 A10 --- Obs.Date Date of observation (2) 65- 75 A11 --- ExpTime Exposure time(s) (in second unit) 78- 80 I3 --- S/N Signal-to-noise ratio 82- 86 F5.1 km/s RV Radial velocity 88- 90 F3.1 km/s e_RV rms uncertainty on RV 92- 96 A5 --- Inst Instrument 98-103 I06 --- StarID Star ID within the cluster (this paper)
Note (1): Origin of star names: Be20 SNNNNNN: Sestito et al. (2008, Cat. J/A+A/488/943), <Cl* Berkeley 20 SBR NNNN> Be22 KNNNN: Kaluzny (1994, Cat. J/A+AS/108/151), <Cl* Berkeley 22 K NNN> Be29 KNNNN: Kaluzny (1994, Cat. J/A+AS/108/151), <Cl* Berkeley 29 K NNN> Be29 TNNNN: Tosi et al. (2004MNRAS.354..225T), <Cl* Berkeley 29 BHT NNN> Be66 PJNNN: Phelps & Janes (1996AJ....111.1604P), <Cl* Berkeley 66 GC NNN> Be73 CCNN: Carraro et al. (2005, Cat. J/A+A/442/917), <Cl* Berkeley 73 CGM NNN> Be75 CCNN: Carraro et al. (2005, Cat. J/A+A/442/917), <Cl* Berkeley 75 CGM NNN> Rup4 CCNN: Carraro et al. (2005, Cat. J/MNRAS/360/655), <Cl* Ruprecht 4 CGB NN> Rup7 CCNN: Carraro et al. (2005, Cat. J/MNRAS/360/655), <Cl* Ruprecht 7 CGB NN>, Sau1 CIII: ID from Carraro & Baume (2003, Cat. J/MNRAS/346/18), <[CB2003] 1-NNNN> Tom2 PIII: Phelps et al. (1994AJ....107.1079P), <Cl* Tombaugh 2 PJM NNN> Note (2): Only the month (or year) is given for stars observed during multiple nights. One star in Be 29 (K801=T398) was observed with both HIRES and UVES.
Byte-by-byte Description of file: table.dat
Bytes Format Units Label Explanations
1- 4 A4 --- Cluster Cluster name 7- 12 I06 --- StarID Star ID within the cluster (this paper) 15- 22 F8.3 0.1nm lambda Wavelength 25- 28 F4.1 --- El Element 31- 35 F5.3 eV Ep Excitation potential 38- 43 F6.3 [-] loggf Oscillator strength 46- 50 F5.1 0.1pm EW Equivalent width
Acknowledgements: Tristan Cantat-Gaudin, tristan.cantat(at)oapd.inaf.it
(End) Patricia Vannier [CDS] 29-Feb-2016
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