We present calculations for the evolution and surviving mass of highly-irradiated extrasolar giant planets (EGPs) at orbital semimajor axes ranging from 0.023 to 0.057 AU using a generalized scaled theory for mass loss, together with new surface-condition grids for hot EGPs and a consistent treatment of tidal truncation. Theoretical estimates for the rate of energy-limited hydrogen escape from giant-planet atmospheres differ by two orders of magnitude, when one holds planetary mass, composition, and irradiation constant. Baraffe et al. (2004, A&A 419, L13-L16) predict the highest rate, based on the theory of Lammer et al. (2003, Astrophys. J. 598, L121-L124). Scaling the theory of Watson et al. (1981, Icarus 48, 150-166) to parameters for a highly-irradiated exoplanet, we find an escape rate ~10 2 lower than Baraffe's. With the scaled Watson theory we find modest mass loss, occurring early in the history of a hot EGP. In this theory, mass loss including the effect of Roche-lobe overflow becomes significant primarily for masses below a Saturn mass, for semimajor axes ≥ 0.023 AU. This contrasts with the Baraffe model, where hot EGPs are claimed to be remnants of much more massive bodies, originally several times Jupiter and still losing substantial mass fractions at present. IntroductionAt present considerable uncertainty exists as to whether extrasolar giant planets (EGPs) are likely to suffer appreciable mass loss over their lifetime when subjected to high levels of XUV irradiation from their host star. A major question concerning the origin of short-period (period P ~ days, semimajor axis a ~ few ×10−2 AU) EGPs concerns this point: do short-period (hot) EGPs originate with their presently-observed masses at a ~ 10 AU and migrate rapidly to a ~ few ×10−2 AU without appreciable mass loss, or were the original bodies several times more massive, suffering continual rapid mass loss throughout their evolution? The latter scenario, advocated by Baraffe et al. (2004), implies that the observed hot EGPs are remnants of much more massive objects and are continuing to lose mass at a significant rate at present. However, as we show in this paper, a theory based on the results of Watson et al. (1981) implies that only hydrogen-rich EGPs with mass M < 0.2 M J (where M J = Jupiter's mass) will be significantly affected by mass loss.We do not present here any independent calculations of the escape rate Φ (molecules cm −2 s −1 ) as a function of Q 0 (erg cm −3 s −1 ), the volume-heating rate of the planetary atmosphere due to absorption of stellar XUV radiation. For energy-limited escape, the two quantities are proportional. As we discuss below, for fixed XUV irradiation from a solar-type star, the Watson theory gives a proportionality constant, and therefore an atmospheric escape rate, that is 10 (2006), we find that the revised Yelle escape rate is no longer an outlier but rather lies between the Baraffe rate and the scaled Watson rate. Thus, the purpose of the present paper is to present, side by side, the implic...
Individuals with identical gene mutations showed a wide variation in the supernumerary tooth formation. Not only the genotype but also environmental factors and a complex system including epigenetics and copy number variation might regulate supernumerary tooth formation in CCD.
The present study suggests the involvement of non-genetic or epigenetic regulation in supernumerary tooth formation in CCD.
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