Metal Licity And Classification Of M Dwarf Stars

M dwarfs (0.08M⊙<M<0.8M⊙) are by far the most numerous class of stars inthe solar neighborhood and are generally believed to account for most of the stellarmass. Stars with such small masses have life time long enough that we can see themtoday, although they formed in the earliest period of our Galaxy. By observing thiskind of stars, we can check the kinetic and chemical abundance information of all theperiod that the Milk Way have evolved.In2012, Woolf et al. have suggested ‘the M dwarf problem’, namely that thepredicted the number of metal-poor M dwarfs are overestimated by the ‘SimpleGalaxy chemical evolution model’. We used the spectra from the LAMOSTpilot Survey to find the M dwarf stars, and divided them into several subtypes. Thenthe [Fe/H] of the M dwarfs are calculated based on the line indices. We compared ourresults to these from Woolf et al.The details are listed as following:(1) We used the HAMMER program to determine the spectra type, and get the Mdwarfs from the LAMOST database.(2) Several ways are used to measure the radial velocities, and finally the method,which the SDSS standard spectra have been used to match the LAMOST M dwarfspectra, was used to determine the radial velocities.(3)76line indices have been measured based on the HAMMER program, andused to estimate the [Fe/H]. We derived the absolute magnitude of these M dwarfsbased on the photometry information, and estimated the distances and the heights forthese stars. Our stars are within a distance of+600pc from the Galaxy plane.(4) Similar to Woolf, our results support the suggestion that there is a ‘M dwarfproblem’.(5) We also find some Li rich stars in the spectra database.