  LHS1070 is a nearby multiple system of low mass stars. It is an important
source of information for probing the low mass end of the main sequence, down
to the hydrogen-burning limit. The primary of the system is a mid-M dwarf and
two components are late-M to early L dwarfs, at the star-brown dwarf
transition. Hence LHS1070 is a valuable object to understand the onset of dust
formation in cool stellar atmospheres.This work aims at determining the
fundamental stellar parameters of LHS1070 and to test recent model atmospheres:
BT-Dusty,BT-Settl, DRIFT, and MARCS models.Unlike in previous studies, we have
performed a chi^2-minimization comparing well calibrated optical and infrared
spectra with recent cool star synthetic spectra leading to the determination of
the physical stellar parameters Teff, radius, and log g for each of the three
components of LHS1070.
