Debris disks are believed to be related to planetesimals left over around
stars after planet formation has ceased. The frequency of debris disks around
M-dwarfs which account for 70% of the stars in the Galaxy is unknown while
constrains have already been found for A- to K-type stars. We have searched for
cold debris disks around 32 field M-dwarfs by conducting observations at lambda
= 850 microns with the SCUBA bolometerarray camera at the JCMT and at lambda =
1.2mm with the MAMBO array at the IRAM 30-m telescopes. This is the first
survey of a large sample of M-dwarfs conducted to provide statistical
constraints on debris disks around this type of stars. We have detected a new
debris disk around the M0.5 dwarf GJ842.2 at lambda = 850 microns, providing
evidence for cold dust at large distance from this star (~ 300AU). By combining
the results of our survey with the ones of Liu et al. (2004), we estimate for
the first time the detection rate of cold debris disks around field M-dwarfs
with ages between 20 and 200 Myr. This detection rate is 13^{+6}_{-8} % and is
consistent with the detection rate of cold debris disks (9 - 23 %) around A- to
K-type main sequence stars of the same age. This is an indication that cold
disks may be equally prevalent across stellar spectral types.Comment: A&A accepted on 15 september 200