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J/A+A/610/A66      Equivalent widths of 7 stars in NGC 6705 (Casamiquela+, 2018)

NGC6705 a young alpha-enhanced open cluster from OCCASO data. Casamiquela L., Carrera R., Balaguer-Nunez L., Jordi C., Chiappini C., Anders F., Antoja T., Miret-Roig N., Romero-Gomez M., Blanco-Cuaresma S., Pancino E., Aguado D.S., del Pino A., Diaz-Perez L., Gallart C. <Astron. Astrophys. 610, A66 (2018)> =2018A&A...610A..66C (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Abundances ; Equivalent widths Keywords: stars: abundances - open clusters and associations: individual: NGC 6705 (M 11) Abstract: The stellar [α/Fe] abundance is sometimes used as a proxy for stellar age, following standard chemical evolution models for the Galaxy, as seen by different observational results. In this work we show that the Open Cluster NGC6705/M11 has a significant α-enhancement [α/Fe]>0.1dex, despite its young age (∼300Myr), challenging the current paradigm.{We use high resolution (R$>65,000$) high signal-to-noise (∼70) spectra of 8 Red Clump stars, acquired within the OCCASO survey. We determine very accurate chemical abundances of several α elements, using an equivalent width methodology (Si, Ca and Ti), and spectral synthesis fits (Mg and O). We obtain [Si/Fe]=0.13±0.05, [Mg/Fe]=0.14±0.07, [O/Fe]=0.17±0.07, [Ca/Fe]=0.06±0.05 and [Ti/Fe]=0.03±0.03. Our results place these cluster within the group of young [α/Fe]-enhanced field stars recently found by several authors in the literature. The ages of our stars have an uncertainty of around 50Myr, much more precise than for field stars. By integrating the cluster's orbit in several non-axisymmetric Galactic potentials, we establish the M11's most likely birth radius to lie between 6.8-7.5kpc from the Galactic center, not far from its current position. With the robust Open Cluster age scale, our results prove that a moderate [α/Fe]-enhancement is no guarantee for a star to be old, and that not all α-enhanced stars can be explained with an evolved blue straggler scenario. Based on our orbit calculations, we further argue against a Galactic bar origin of M11. Description: We present a high-resolution spectroscopic study centered in the abundances of alpha elements of 7 member stars in NGC 6705. We include the equivalent widths of CaI, SiI and TiI lines derived for 14 spectra. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 120 11 Details of the observed stars table2.dat 68 79 *Equivalent widths of CaI, SiI and TiI lines
Note on table2.dat: -99 indicates that the equivalent width of the line could not be measured.
See also: J/A+A/513/A29 : RACE-OC project: M11 (NGC6705) (Messina+, 2010) J/A+A/569/A17 : Gaia-ESO Survey: NGC6705 (Cantat-Gaudin+, 2014) J/A+A/573/A55 : Gaia-ESO Survey: Tr 20, NGC4815, NGC6705 (Tautvaisiene+, 2015) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 5 A5 --- Name Star name from WEBDA (WNNNN) 7- 8 I2 h RAh Right ascension (J2000) 10- 11 I2 min RAm Right ascension (J2000) 13- 18 F6.3 s RAs Right ascension (J2000) 20 A1 --- DE- Declination sign (J2000) 21- 22 I2 deg DEd Declination (J2000) 24- 25 I2 arcmin DEm Declination (J2000) 27- 31 F5.2 arcsec DEs Declination (J2000) 33- 36 F4.1 mag Vmag V magnitude from literature (from literature) 38- 41 F4.2 --- Pmemb Probability of membership from proper motion (from McNamara et al., 1977A&AS...27..117M) 43- 44 A2 --- Class1 [M SM] Classification from radial velocity (1) 45 A1 --- r_Class1 Reference for Class1 (2) 46 A1 --- --- [,] 48- 49 A2 --- Class2 [M SM] Classification from radial velocity (1) 50 A1 --- r_Class2 Reference for Class2 (2) 51 A1 --- --- [,] 53 A1 --- Class3 [M SM] Classification from radial velocity (1) 54 A1 --- r_Class3 Reference for Class3 (2) 56- 61 A6 --- Inst Instrument 63- 64 I2 --- SNR Signal-to-noise ratio of the spectrum 66- 69 I4 K Teff Effective temperature from spectroscopic analysis 71- 73 I3 K e_Teff rms uncertainty on Teff 75- 78 F4.2 [cm/s2] logg Surface gravity from spectroscopic analysis 80- 83 F4.2 [cm/s2] e_logg rms uncertainty on logg 85- 88 F4.2 km/s vt Microturbulent velocity from EW 90- 93 F4.2 km/s e_vt rms uncertainty on vt 95- 98 F4.1 km/s RV Radial velocity from spectroscopic analysis 100-102 F3.1 km/s e_RV rms uncertainty on RV 104-107 F4.2 [-] [Fe/H] Metallicity from EW 109-112 F4.2 [-] e_[Fe/H] rms uncertainty on [Fe/H] 114-120 A7 --- Label Name of the column in table2 with equivalent width data
Note (1): Classification as follows: M = member SM = single member Note (2): References as follows: a = Cantat-Gaudin et al. (2014, Cat. J/A+A/569/A17) and Tautvaisiene et al. (2015, Cat. J/A+A/573/A55), b = Mathieu et al. (1986AJ.....92.1100M), c = Mermilliod et al. (2008, Cat. J/A+A/485/303)
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 8 F8.3 0.1nm Lambda Wavelength of the line 10- 12 A3 --- Element Name of the chemical species 14- 19 F6.3 [-] loggf Logarithm of the oscillation strength 21- 24 F4.2 eV EP Excitation potential 26- 28 I3 0.1pm EW0660H ?=-99 Equivalent width of the spectrum W0660_HER 30- 32 I3 0.1pm EW0669H ?=-99 Equivalent width of the spectrum W0669_HER 34- 36 I3 0.1pm EW0686H ?=-99 Equivalent width of the spectrum W0686_HER 38- 40 I3 0.1pm EW0779H ?=-99 Equivalent width of the spectrum W0779_HER 42- 44 I3 0.1pm EW0779F ?=-99 Equivalent width of the spectrum W0779_FIE 46- 48 I3 0.1pm EW0916H ?=-99 Equivalent width of the spectrum W0916_HER 50- 52 I3 0.1pm EW1184H ?=-99 Equivalent width of the spectrum W1184_HER 54- 56 I3 0.1pm EW1184F ?=-99 Equivalent width of the spectrum W1184_FIE 58- 60 I3 0.1pm EW1256H ?=-99 Equivalent width of the spectrum W1256_HER 62- 64 I3 0.1pm EW1423H ?=-99 Equivalent width of the spectrum W1423_HER 66- 68 I3 0.1pm EW1423F ?=-99 Equivalent width of the spectrum W1423_FIE
Acknowledgements: Laia Casamiquela, laiacf(at)
(End) Laia Casamiquela [Univ. Barcelona], Patricia Vannier [CDS] 06-Nov-2017
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