What sort of atmospheric temperatures would the orbit of HD 69830d, the habitable zone planet, produce?
A. HD69830d is probably more like Uranus and Neptune than like a terrestrial planet, i.e. it probably has a large hydrogen envelope. Therefore there is no “surface” on this planet and one cannot speak of an atmosphere like on Earth. Q. Does anything preclude the existence of smaller planets orbiting this star in its habitable zone? Specifically, within the outer asteroid belt you describe as a possibility? A. We have not investigated the dynamical stability of a hypothetical Earth-mass planet orbiting between ~0.8 and ~1 AU. Nonetheless, as this zone is stable for asteroids, it is likely to be stable as well for small telluric planets. Q. The paper seems to suggest an either/or possibility of an inner and outer asteroid belt around this star. Why couldn’t there be both? A. There could actually be both. Further observations and theoretical modeling will probably yield better constraints on the precise location of the debris disk. Q. Is it fair to say this is the smallest planet discover