J/MNRAS/396/1895 MgI and sTiO index definitions (Cenarro+, 2009) ================================================================================ Mg and TiO spectral features at the near-IR: spectrophotometric index definitions and empirical calibrations. Cenarro A.J., Cardiel N., Vazdekis A., Gorgas J. =2009MNRAS.396.1895C ================================================================================ ADC_Keywords: Clusters, globular ; Spectroscopy Keywords: stars: abundances - stars: fundamental parameters - globular clusters: general - galaxies: stellar content Abstract: Using the near-infrared spectral stellar library of Cenarro et al. (J/MNRAS/326/959), the behaviour of the MgI line at 8807{AA} and nearby TiO bands is analyzed in terms of the effective temperature, surface gravity and metallicity of the library stars. New spectroscopic indices for both spectral features - namely MgI and sTiO - are defined, and their sensitivities to different signal-to-noise ratios, spectral resolutions, flux calibrations and sky emission-line residuals are characterized. The two new indices exhibit interesting properties. In particular, MgI is a good indicator of the Mg abundance, whereas sTiO is a powerful dwarf-to-giant discriminator for cold spectral types. Empirical fitting polynomials that reproduce the strength of the new indices as a function of the stellar atmospheric parameters are computed, and a fortran routine with the fitting function predictions is made available. A thorough study of several error sources, non-solar [Mg/Fe] ratios and their influence on the fitting function residuals is also presented. From this analysis, an [Mg/Fe] underabundance of ~-0.04 is derived for the Galactic open cluster M67. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 96 5 Definition of previous and new indices for the near-IR MgI line ({lambda} 8807{AA}) and TiO bands ({lambda}{lambda} 8432, 8442, 8452{AA}; {lambda}{lambda} 8860, 8868{AA}) table10.dat 103 706 *MgI and sTiO index measurements -------------------------------------------------------------------------------- Note on table10.dat: Additional information for the library stars (e.g. atmospheric parameters, [Ca/Fe] abundances, CaT, PaT, and CaT* index values, their errors and fitting function residuals, B and V apparent magnitudes, signal-to-noise ratios per angstrom, and other names) can be found at Cenarro et al., (2001, Cat. J/MNRAS, 326, 959 and 2001MNRAS.326..981C) and at http://www.ucm.es/info/Astrof/ellipt/MgIsTiO.html -------------------------------------------------------------------------------- See also: J/MNRAS/326/959 : Near-IR Ca triplet empirical calibration (Cenarro+ 2001) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- Index Index name 6- 8 A3 --- Ref Reference code (1) 10- 12 A3 --- Type Type (2) 14- 26 A13 0.1nm lambda Central bandpass 28- 40 A13 0.1nm lambdaCont1 Continuum bandpass 42- 54 A13 0.1nm lambdaCont2 Continuum bandpass 56- 68 A13 0.1nm lambdaCont3 Continuum bandpass 70- 82 A13 0.1nm lambdaCont4 Continuum bandpass 84- 96 A13 0.1nm lambdaCont5 Continuum bandpass -------------------------------------------------------------------------------- Note (1): Codes for the references are as follow: CVP = Carter et al., 1986ApJ...311..637C DTT = Diaz et al. 1989MNRAS.239..325D TW = this work Note (2): Types as follows: c-a = classical-atomic index c-m = classical-molecular index g-s = generic-atomic and generic-slope-like indices -------------------------------------------------------------------------------- Byte-by-byte Description of file: table10.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 I3 --- Seq Sequential number 5- 18 A14 --- Name Star name 20- 21 I2 h RAh Right ascension (J2000) 23- 24 I2 min RAm Right ascension (J2000) 26- 29 F4.1 s RAs Right ascension (J2000) 31 A1 --- DE- Declination sign (J2000) 32- 33 I2 deg DEd Declination (J2000) 35- 36 I2 arcmin DEm Declination (J2000) 38- 39 I2 arcsec DEs Declination (J2000) 40 A1 --- r [*S] Remark on the position (1) 42- 54 A13 --- SpType MK spectral type 57- 62 F6.3 0.1nm MgI MgI index measurement 64- 68 F5.3 0.1nm e_MgI rms uncertainty on MgI (2) 70- 75 F6.3 0.1nm dMgI ? Fitting function residual for MgI 77- 81 F5.3 0.1nm sTiO sTiO index measurement 83- 87 F5.3 0.1nm e_sTiO rms uncertainty on sTiO (2) 89- 94 F6.3 0.1nm dsTiO ? Fitting function residual for IsTiO 96-101 F6.3 [-] [Mg/Fe] ? [Mg/Fe] abundances (when available) 103 I1 --- r_[Mg/Fe] ? Reference for [Mg/Fe] (3) -------------------------------------------------------------------------------- Note (1): Note on position as follows: * = original position in B1950, transformed into J2000 by CDS S = position from Simbad Database Note (2): accounting for photon noise and typical uncertainties in radial velocity Note (3): Sources for [Mg/Fe] values as follows: 1 = the catalogue of spectroscopic abundances in stars (Borkova & Marsakov, 2005, Cat. J/AZh/82/453) 2 = the catalogue of chemical abundances in late-type stars (Thevenin 1998, Cat. III/193) corrected to the Borkova & Marsakov (2005, Cat. J/AZh/82/453) system 3 = Pilachowski, Sneden & Kraft (1996AJ....111.1689P) 4 = Gratton & Sneden (1987A&A...178..179G) -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Patricia Vannier [CDS] 01-Apr-2011