Tidal Heating of Extrasolar Planets

By B. Jackson, Richard Greenberg, R. Barnes. 2008

153 citations recorded by the source corpus.

Extrasolar planets close to their host stars have likely undergone significant tidal evolution since the time of their formation. Tides probably dominated their orbital evolution once the dust and gas cleared away, and as the orbits evolved there was substantial tidal heating within the planets. The tidal heating history of each planet may have contributed significantly to the thermal budget governing the planet's physical properties, including its radius, which in many cases may be measured by observing transit events. Typically, tidal heating increases as a planet moves inward toward its star and then decreases as its orbit circularizes. Here we compute the plausible heating histories for several planets with measured radii, using the same tidal parameters for the star and planet that have been shown to reconcile the eccentricity distribution of close-in planets with other extrasolar planets. Several planets are discussed, including, for example, HD 209458b, which may have undergone substantial tidal heating during the past billion years, perhaps enough to explain its large measured radius. Our models also show that GJ 876d may have experienced tremendous heating and is probably not a solid, rocky planet. Theoretical models should include the role of tidal heating, which is large but time-varying.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/8d72fadfcd324f31762a1537c19f755e9b4b0e18

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In Astronomy and Astrophysics

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Citations in the corpus

• Is tidal heating sufficient to explain bloated exoplanets? Consistent calculations accounting for finite initial eccentricity (2010, methodology): “Following Bodenheimer et al. (2001) and Gu et al. (2003), attempts have been made to explain the observed large radius of some transiting close-in gas giant exoplanets - the so-called ”Hot Jupiters” - by means of tidal heating (Jackson et al. 2008; Miller et al. 2009; Ibgui et al. 2009).”
• On the tidal evolution of Hot Jupiters on inclined orbits (2009, background): “This estimate also appears consistent with the work of Jackson et al. (2008a), who found that one can reproduce the outer planet (a > 0.2 AU) eccentricity distribution from integrating the tidal evolution equations backwards in time for the observed close–in planets (a < 0.2 AU) quite well if Q ∼…”
• KEPLER-18b, c, AND d: A SYSTEM OF THREE PLANETS CONFIRMED BY TRANSIT TIMING VARIATIONS, LIGHT CURVE VALIDATION, WARM-SPITZER PHOTOMETRY, AND RADIAL VELOCITY MEASUREMENTS (2011, background): “We do not include an internal heating contribution due to eccentricity damping in either planet, as this power source is expected to fall off as a−15/2 (Jackson et al. 2008) and, furthermore, the eccentricities suggested by the TTV solutions are quite small.”
• CHEMISTRY OF SILICATE ATMOSPHERES OF EVAPORATING SUPER-EARTHS (2009, background): “Tidal forces are also very strong and can generate sufficient heat to melt a silicate planet larger than the Earth (e.g. Jackson et al. 2008a, b; Ganesan et al. 2008).”
• The Interior Structure, Composition, and Evolution of Giant Planets (2009, background): “Jackson et al. (2008a) have shown the orbits of hot Jupiters are still decaying due to the tide raised on the star by the planet, and that tidal heating in the not-to-distant past could have been appreciable (Jackson et al. 2008b).”
• Transiting exoplanets from the CoRoT space mission . VI. CoRoT-Exo-3b: the first secure inhabitant of the brown-dwarf desert (2008, background): “Given the relatively large mass and short period of the companion, one might expect it to have synchronized the rotation of its host star to its orbital period via tidal interaction (Dobbs-Dixon et al. 2004; Jackson et al. 2008).”
• THE ORBITAL EVOLUTION OF GAS GIANT PLANETS AROUND GIANT STARS (2009, background): “Note that the initial value of the eccentricity has little effect on the orbital decay rate (e.g., Jackson et al. 2008b).”
• OBSERVATIONAL EVIDENCE FOR TIDAL DESTRUCTION OF EXOPLANETS (2009, methodology): “Note that Equations (1) and (2) include corrections to those presented by Jackson et al. (2008a).”