  We have investigated planetary accretion from planetesimals in terrestrial
planet regions inside the ice line around M dwarf stars through N-body
simulations including tidal interactions with disk gas. Because of low
luminosity of M dwarfs, habitable zones (HZs) are located in inner regions. In
the close-in HZ, type-I migration and the orbital decay induced by eccentricity
damping are efficient according to the high disk gas density in the small
orbital radii. In the case of full efficiency of type-I migration predicted by
the linear theory, we found that protoplanets that migrate to the vicinity of
the host star undergo close scatterings and collisions, and 4 to 6 planets
eventually remain in mutual mean motion resonances and their orbits have small
eccentricities and they are stable both before and after disk gas decays. In
the case of slow migration, the resonant capture is so efficient that
densely-packed ~ 40 small protoplanets remain in mutual mean motion resonances.
In this case, they start orbit crossing, after the disk gas decays and
eccentricity damping due to tidal interaction with gas is no more effective.
Through merging of the protoplanets, several planets in widely-separated
non-resonant orbits with relatively large eccentricities are formed. Thus, the
final orbital configurations of the terrestrial planets around M dwarfs
sensitively depend on strength of type-I migration. We also found that large
amount of water-ice is delivered by type-I migration from outer regions and
final planets near the inner disk edge around M dwarfs are generally abundant
in water-ice except for the innermost one that is shielded by the outer
planets, unless type-I migration speed is reduced by a factor of more than 100
from that predicted by the linear theory.
