Dataset of H-alpha activity index for F-, G-, and K-type stars observed by the LAMOST Medium-Resolution Spectroscopic Survey

This dataset of H-alpha activity index is for investigation of stellar chromospheric activity based on the LAMOST Medium-Resolution Spectroscopic Survey (MRS). High signal-to-noise ratio MRS coadded spectra of F-, G-, and K-type stars (4000-7000 K) from LAMOST Data Release 8 (DR8) are utilized in the dataset (329,294 spectra in total). The H-alpha activity index is defined as the ratio of the mean flux of H-alpha center band (width: 0.25 Å) over the mean flux of two continuum bands on the two sides of H-alpha line (distance between continuum band centers: 50 Å; width of each continuum band: 5 Å). The evaluated H-alpha activity index values and their uncertainties, as well as the related spectroscopic parameters from the LAMOST catalogs, are stored in a CSV format file (file name: Halpha_activity_index_LAMOST_MRS_DR8.csv). The data of the H-alpha equivalent width (width of the wavelength range for integral of H-alpha line: 8 Å) are also provided in the dataset for reference. Columns included in the dataset: obsid - unique observation identifier of LAMOST MRS ra - right ascension of the observed object (unit: degree) dec - declination of the observed object (unit: degree) obsdate - UTC date of observation (format: YYYY-MM-DD) fitsname - MRS FITS data file name sn_B - signal-to-noise ratio of the blue-band data of MRS sn_R - signal-to-noise ratio of the red-band data of MRS band_para - indicating which band of MRS is used by the LASP for determining the stellar atmospheric parameters; ‘B’ representing the blue band and ‘R’ representing the red band teff - effective temperature determined by the LASP (unit: K) teff_err - uncertainty of teff (unit: K) logg - surface gravity determined by the LASP (unit: dex) logg_err - uncertainty of logg (unit: dex) feh - metallicity determined by the LASP (unit: dex) feh_err - uncertainty of feh (unit: dex) rv_r0 - radial velocity determined based on the red-band data of MRS (unit: km/s) rv_r0_err - uncertainty of rv_r0 (unit: km/s) category* - ‘main-sequence’ or ‘giant’ or ‘intermediate-zone’ I_halpha* - H-alpha activity index I_halpha_err* - uncertainty of H-alpha activity index W_halpha* - H-alpha equivalent width (unit: Å) (Note: The columns marked with an asterisk are provided by this dataset. Other columns are from the catalogs of LAMOST DR8 v1.1. LASP is an acronym for ‘LAMOST Stellar Parameter Pipeline’. A value of ‘-9999.0’ in the dataset indicates that it is not available.)