J/ApJ/719/996 Effects of binarity in SEGUE pipeline (Schlesinger+, 2010)
Binary contamination in the SEGUE sample: effects on SSPP determinations of stellar atmospheric parameters. Schlesinger K.J., Johnson J.A., Lee Y.S., Masseron T., Yanny B., Rockosi C.M., Gaudi B.S., Beers T.C. <Astrophys. J., 719, 996-1020 (2010)> =2010ApJ...719..996S
ADC_Keywords: Stars, double and multiple ; Abundances ; Photometry, SDSS ; Stars, masses ; Surveys ; Models Keywords: astronomical databases: miscellaneous - binaries: general - surveys - stars: abundances - stars: luminosity function, mass function Abstract: We examine the effects that unresolved binaries have on the determination of various stellar atmospheric parameters for targets from the Sloan Extension for Galactic Understanding and Exploration (SEGUE) using numerical modeling, a grid of synthetic spectra, and the SEGUE Stellar Parameter Pipeline (SSPP). The SEGUE survey, a component of the Sloan Digital Sky Survey-II (SDSS-II) project focusing on Galactic structure, provides medium resolution spectroscopy for over 200000 stars of various spectral types over a large area on the sky. To model undetected binaries that may be in this sample, we use a variety of mass distributions for the primary and secondary stars in conjunction with empirically determined relationships for orbital parameters to determine the fraction of G-K dwarf stars, defined by SDSS color cuts as having 0.48≤(g-r)0≤0.75, that will be blended with a secondary companion. We focus on the G-K dwarf sample in SEGUE as it records the history of chemical enrichment in our galaxy. To determine the effect of the secondary on the spectroscopic parameters, specifically effective temperature, surface gravity, metallicity, and [α/Fe], we synthesize a grid of model spectra from 3275 to 7850K and [Fe/H]=-0.5 to -2.5 from MARCS model atmospheres using TurboSpectrum. These temperature and metallicity ranges roughly correspond to a stellar mass range of 0.1-1.0M☉. We assume that both stars in the pair have the same metallicity. We analyze both "infinite" signal-to-noise ratio (S/N) models and degraded versions of the spectra, at median S/N of 50, 25, and 10. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table4.dat 86 770 Properties of the blended binaries analyzed by the SEGUE Stellar Parameter Pipeline (SSPP) table5.dat 90 770 Differences between the blended binaries and control group primaries
See also: J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009) J/AJ/136/2070 : SEGUE stellar parameter pipeline. III. (Allende Prieto+, 2008) J/AJ/136/2050 : SEGUE stellar parameter pipeline. II. (Lee+, 2008) Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 4 F4.2 Msun M1 [0.5/1.0] Model primary mass 6- 9 F4.2 Msun M2 [0.1/1.0] Model secondary mass 11- 14 F4.1 [-] [Fe/H]m [-2.5/-0.5] Model [Fe/H] metallicity 16- 19 I4 K Teff [4166/8176]? SSPP effective temperature (1) 21- 23 I3 K e_Teff ? Uncertainty in Teff (1) 25- 29 F5.2 [-] [Fe/H] ? SSPP [Fe/H] metallicity (1) 31- 34 F4.2 [-] e_[Fe/H] ? Uncertainty in [Fe/H] (1) 36- 39 F4.2 [cm/s2] log(g) ? SSPP log surface gravity (1) 41- 44 F4.2 [cm/s2] e_log(g) ? Uncertainty in log(g) (1) 46- 50 F5.2 [-] [a/Fe] ? SSPP [alpha/Fe] metallicity (1) 52- 55 F4.2 [-] e_[a/Fe] ? Uncertainty in [a/Fe] (1) 57- 61 F5.2 mag umag The u band magnitude 63- 66 F4.2 mag gmag The g band magnitude 68- 71 F4.2 mag rmag The r band magnitude 73- 76 F4.2 mag imag The i band magnitude 78- 81 F4.2 mag zmag The z band magnitude 83- 86 F4.2 mag g-r The (g-r) color index
Note (1): Note that there are no temperature or metallicity measurements for stars cooler than 4000K, and no [α/Fe] values for stars with temperatures greater than 7500K or less than 4500K.
Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 4 F4.2 Msun M1 [0.5/1.0] Model primary mass 6- 9 F4.2 Msun M2 [0.1/1.0] Model secondary mass 11- 14 F4.1 [-] [Fe/H]m [-2.5/-0.5] Model [Fe/H] metallicity 16- 18 I3 K DTeff ? Differential effective temperature (1) 20- 22 I3 K e_DTeff ? Uncertainty in DTeff 24- 28 F5.2 [-] D[Fe/H] ? Differential [Fe/H] metallicity (1) 30- 33 F4.2 [-] e_D[Fe/H] ? Uncertainty in D[Fe/H] 35- 39 F5.2 [cm/s2] Dlog(g) ? Differential log surface gravity (1) 41- 44 F4.2 [cm/s2] e_Dlog(g) ? Uncertainty in Dlog(g) 46- 50 F5.2 [-] D[a/Fe] ? Differential [alpha/Fe] metallicity (1) 52- 55 F4.2 [-] e_D[a/Fe] ? Uncertainty in D[a/Fe] 57- 61 F5.2 mag Dumag Differential u band magnitude (1) 63- 66 F4.2 mag Dgmag Differential g band magnitude (1) 68- 72 F5.2 mag Drmag Differential r band magnitude (1) 74- 78 F5.2 mag Dimag Differential i band magnitude (1) 80- 84 F5.2 mag Dzmag Differential z band magnitude (1) 86- 90 F5.2 mag Dg-r Differential (g-r) color index (1)
Note (1): The differences calculated are the values for the binaries with the primary values subtracted. Note that there are no temperature or metallicity measurements for stars less than 4000K, and no [α/Fe] values for stars with temperatures greater than 7500K or less than 4500K.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 18-Jun-2012
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