Comparison of Different Interpolation Algorithm in Feature-based Template Matching for Stellar Parameters Analysis

Referring to SDSS/SEGUE pipeline for stellar parameters SSPP and other pipelines, two methods, ULySS(9,10) and CFI (correlation function interpolation) are investigated to estimate stellar parameters (effective temperature, surface gravity, and metallicity) for AFGK stars based on medium-resolution spectroscopy. Both of the two methods carry with an interpolator, ULySS provides with an interpolator of the template library consisting of polynomial expansions of each wavelength element in powers of stellar parameters while CFI interpolates the maximal correlation coefficent as functions of stellar parameters. Comparing with known objects observed by the Sloan Digital Sky Survey (SDSS), their performances are tested, random and systematic errors are examined. By comparing CFI with ULySS, performances of different interpolations are tested. These two methods will be integrated into LAMOST stellar parameter pipeline (LASP) and used for the data release of the LAMOST pilot survey.