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CoRoT-7 b, a planet about 70% larger than the Earth orbiting a Sun-like star, is the first-discovered rocky exoplanet, and hence has been dubbed a "super-Earth". Some initial studies suggested that since the planet is so close to its host star, it receives enough insolation to partially melt its surface. However, these past studies failed to take into consideration the role that tides may play in this system. Even if the planet's eccentricity has always been zero, we show that tidal decay of semi-major axis could have been large enough that the planet formed on a wider orbit which received less insolation. Moreover, CoRoT-7 b could be tidally heated at a rate that dominates its geophysics and drives extreme volcanism. In this case, CoRoT-7 b is a "super-Io" that, like Jupiter's volcanic moon, is dominated by volcanism and rapid resurfacing. Such heating could occur with an eccentricity of just 10^-5. This small value could be driven by CoRoT-7 c if its own eccentricity is larger than ~10^-4. CoRoT-7 b may be the first of a class of planetary super-Ios likely to be revealed by the CoRoT and Kepler spacecraft., 13 pages, 3 figures, accepted to ApJ Letters

The habitable zones of main sequence stars have traditionally been defined as the range of orbits that intercept the appropriate amount of stellar flux to permit surface water on a planet. Terrestrial exoplanets discovered to orbit M stars in these zones, which are close-in due to decreased stellar luminosity, may also undergo significant tidal heating. Tidal heating may span a wide range for terrestrial exoplanets and may significantly affect conditions near the surface. For example, if heating rates on an exoplanet are near or greater than that on Io (where tides drive volcanism that resurface the planet at least every 1 Myr) and produce similar surface conditions, then the development of life seems unlikely. On the other hand, if the tidal heating rate is less than the minimum to initiate plate tectonics, then CO_2 may not be recycled through subduction, leading to a runaway greenhouse that sterilizes the planet. These two cases represent potential boundaries to habitability and are presented along with the range of the traditional habitable zone for main sequence, low-mass stars. We propose a revised habitable zone that incorporates both stellar insolation and tidal heating. We apply these criteria to GJ 581 d and find that it is in the traditional habitable zone, but its tidal heating alone may be insufficient for plate tectonics., 13 pages, 2 figures, accepted to ApJ Letters. A version with full resolution images is available at http://www.astro.washington.edu/users/rory/publications/bjgr09.pdf

The known extrasolar multiple-planet systems share a surprising dynamical attribute: they cluster just beyond the Hill stability boundary. Here we show that the planet-planet scattering model, which naturally explains the observed exoplanet eccentricity distribution, can reproduce the observed distribution of dynamical configurations. We calculated how each of our scattered systems would appear over an appropriate range of viewing geometries; as Hill stability is weakly dependent on the masses, the mass-inclination degeneracy does not significantly affect our results. We consider a wide range of initial planetary mass distributions and find that some are poor fits to the observed systems. In fact, many of our scattering experiments overproduce systems very close to the stability boundary. The distribution of dynamical configurations of two-planet systems actually may provide better discrimination between scattering models than the distribution of eccentricity. Our results imply that, at least in their inner regions which are weakly affected by gas or planetesimal disks, planetary systems should be "packed", with no large gaps between planets., Comment: Accepted to ApJ Letters. 5 pages, 2 figures, 2 tables

Gas giant planets are far easier than terrestrial planets to detect around other stars, and are thought to form much more quickly than terrestrial planets. Thus, in systems with giant planets, the late stages of terrestrial planet formation are strongly affected by the giant planets' dynamical presence. Observations of giant planet orbits may therefore constrain the systems that can harbor potentially habitable, Earth-like planets. We present results of 460 N-body simulations of terrestrial accretion from a disk of Moon- to Mars-sized planetary embryos. We systematically vary the orbital semimajor axis of a Jupiter-mass giant planet between 1.6 and 6 AU, and eccentricity between 0 and 0.4. We find that for Sun-like stars, giant planets inside roughly 2.5 AU inhibit the growth of 0.3 Earth-mass planets in the habitable zone. If planets accrete water from volatile-rich embryos past 2-2.5 AU, then water-rich habitable planets can only form in systems with giant planets beyond 3.5 AU. Giant planets with significant orbital eccentricities inhibit both accretion and water delivery. The majority of the current sample of extra-solar giant planets appears unlikely to form habitable planets., Accepted by ApJ Letters

The ``minimum-mass solar nebula'' (MMSN) model estimates the surface density distribution of the protoplanetary disk by assuming the planets to have formed in situ. However, significant radial migration of the giant planets likely occurred in the Solar system, implying a distortion in the values derived by the MMSN method. The true density profiles of protoplanetary disks is therefore uncertain. Here we present results of simulations of late-stage terrestrial accretion, each starting from a disk of planetary embryos. We assume a power-law surface density profile that varies with heliocentric distance r as r^-alpha, and vary alpha between 1/2 and 5/2 (alpha = 3/2 for the MMSN model). We find that for steeper profiles (higher values of alpha), the terrestrial planets (i) are more numerous, (ii) form more quickly, (iii) form closer to the star, (iv) are more massive, (v) have higher iron contents, and (vi) have lower water contents. However, the possibility of forming potentially habitable planets does not appear to vary strongly with alpha., Comment: 10 pages, 5 figures in emulateapj style. tp appear in Oct 20, 2005, issue of ApJ

We present Rossiter-McLaughlin observations of the transiting super-Earth 55 Cnc e collected during six transit events between January 2012 and November 2013 with HARPS and HARPS-N. We detect no radial-velocity signal above 35 cm/s (3-sigma) and confine the stellar v sin i to 0.2 +/- 0.5 km/s. The star appears to be a very slow rotator, producing a very low amplitude Rossiter-McLaughlin effect. Given such a low amplitude, the Rossiter-McLaughlin effect of 55 Cnc e is undetected in our data, and any spin-orbit angle of the system remains possible. We also performed Doppler tomography and reach a similar conclusion. Our results offer a glimpse of the capacity of future instrumentation to study low amplitude Rossiter-McLaughlin effects produced by super-Earths., Comment: Accepted for publication in ApJ Letters