  In light of the growing interest in searching for low mass, rocky planets, we
investigate the impact of starspots on radial velocity searches for earth-mass
planets in orbit about M dwarf stars. Since new surveys targeting M dwarfs will
likely be carried out at infrared wavelengths, a comparison between V and Y
band starspot induced jitter is made, indicating a reduction of up to an order
of magnitude when observing in the Y band. The exact reduction in jitter is
dependent on the photosphere to spot contrast ratio, with greater improvements
at smaller contrasts. We extrapolate a model used to describe solar spot
distributions to simulate the spot patterns that we expect to find on M dwarfs.
Under the assumption that M dwarfs are near or fully convective, we randomly
place starspots on the stellar surface, simulating different levels of spot
coverage. Line profiles, distorted by spots are derived and are used to
investigate the starspot induced jitter. By making assumptions about the degree
of spot activity, detection limits for earth-mass planets in habitable zones
are simulated for between 10 and 500 observation epochs. We find that <= 50
epochs are required to detect 1 - 2 MEarth planets (with < 1 per cent false
alarm probability) orbiting slowly rotating 0.1 and 0.2 MSun stars. This
sensitivity decreases when typical rotation velocities and activity levels for
each stellar mass/spectral type are considered. No detections of below 20
MEarth planets are expected for <= 500 observations for the most active stars
with vsini >= 20 km/s and dark spots.

Solar and Stellar Astrophysics