The luminosity function for late M-stars

A search for low luminosity M-stars is described. A sample is obtained on the basis of (R - I) colour which gives a space density distribution similar to earlier work for Msub(R) < 14, but shows a subsequent increase in space density for the faintest stars. The implications of these stars for the problem of missing mass in the neighbourhood of the sun is discussed. It is concluded that these stars form part of a population of substellar brown dwarfs which may make up the mass deficit in the solar neighbourhood. (author)