Planetary Transits and Tidal Evolution

TL;DR

This paper investigates how tidal forces influence the orbital and physical evolution of transiting exoplanets, affecting their observed properties and survey biases, with implications for understanding planetary system development.

Contribution

It provides detailed calculations of tidal evolution effects on transiting planets and discusses their impact on planetary characteristics and observational biases.

Findings

Tidal heating can explain large planetary radii, such as TrES-4.

Tidal evolution affects transit probabilities and may bias survey results.

Younger ages of transiting planets suggest tidal destruction of close-in planets.

Abstract

Transiting planets are generally close enough to their host stars that tides may govern their orbital and thermal evolution of these planets. We present calculations of the tidal evolution of recently discovered transiting planets and discuss their implications. The tidal heating that accompanies this orbital evolution can be so great that it controls the planet's physical properties and may explain the large radii observed in several cases, including, for example, TrES-4. Also because a planet's transit probability depends on its orbit, it evolves due to tides. Current values depend sensitively on the physical properties of the star and planet, as well as on the system's age. As a result, tidal effects may introduce observational biases in transit surveys, which may already be evident in current observations. Transiting planets tend to be younger than non-transiting planets, an indication that tidal evolution may have destroyed many close-in planets. Also the distribution of the masses of transiting planets may constrain the orbital inclinations of non-transiting planets.