We construct high signal-to-noise “ template ” spectra by co-adding hundreds of spectra of nearby dwarfs spanning K7 to M4 , taken with Keck/HIRES as part of the California Planet Search .
We identify several spectral regions in the visible ( 370 - 800 nm ) that are sensitive to the stellar luminosity and metallicity .
We use these regions to develop a spectral calibration method to measure the mass , metallicity , and distance of low-mass stars , without the requirement of geometric parallaxes .
Testing our method on a sample of nearby M dwarfs we show that we can reproduce stellar masses to about 8 - 10 % , metallicity to \sim 0.15 dex and distance to 11 % .
We were able to make use of HIRES spectra obtained as part of the radial velocity monitoring of the star KOI-314 to derive a new mass estimate of 0.57 \pm 0.05 M _ { \odot } , a radius of 0.54 \pm 0.05 R _ { \odot } , a metallicity , [ Fe/H ] , of -0.28 \pm 0.10 and a distance of 66.5 \pm 7.3 pc .
Using HARPS archival data and combining our spectral method with constraints from transit observations , we are also able to derive the stellar properties of GJ 3470 , a transiting planet hosting M dwarf .
We estimate a mass of 0.53 \pm 0.05 M _ { \odot } , a radius of 0.50 \pm 0.05 R _ { \odot } , a metallicity , [ Fe/H ] , of 0.12 \pm 0.12 and a distance of 29.9 \pm _ { 3.4 } ^ { 3.7 } pc .