Terrestrial Planets in M dwarf Habitable Zones

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There was a pretty interesting paper that came out a little over a week ago entitled: "Planets Formed in Habitable Zones of M Dwarf Stars Probably are Deficient in Volatiles" a preprint can be obtained here:<br />http://xxx.lanl.gov/abs/astro-ph/0703576<br /><br />The abstract is:<br />"Dynamical considerations, presented herein via analytic scalings and numerical experiments, imply that Earth-mass planets accreting in regions that become habitable zones of M dwarf stars form within several million years. Temperatures in these regions during planetary accretion are higher than those encountered by the material that formed the Earth. Collision velocities during and after the prime accretionary epoch are larger than for Earth. These factors suggest that planets orbiting low mass main sequence stars are likely to be either too distant (and thus too cold) for carbon/water based life on their surfaces or have abundances of the required volatiles that are substantially less than on Earth."<br /><br />When you also consider that earth mass planets in the habitable zones of M-dwarfs are likely to be tidally synchronized to their stars and that M-dwarfs have violent flares it does seem that the cards are stacking up against life around M-dwarfs. It's a bit of a shame though really because M-dwarfs represent something like 75% of the stars in our galaxy. <div class="Discussion_UserSignature"> </div>