Origin of hot Jupiters

5 problems

• Which formation channel produces most hot Jupiters?

  Open

  Three routes could make hot Jupiters, and each leaves different marks on orbits and neighbors. The share of each route is not known.

• Why are hot Jupiters around hotter stars often misaligned?

  Open

  Around cool stars, hot Jupiters usually orbit in the plane of the star's equator; around hotter stars their orbits are often tilted or even backward. Either tides straighten orbits only around cool stars, or the planets arrived differently.

• Why are many hot Jupiters larger than models predict?

  Open

  Strongly heated giant planets are often puffier than any standard cooling model allows. Some extra heat must be deposited deep inside them.

• What is the tidal dissipation factor of Sun-like stars?

  Open

  Tides raised by a close giant planet on its star slowly drag the planet inward. How strongly stars dissipate tidal energy decides how long hot Jupiters survive.

• How did warm Jupiters on 10 to 200 day orbits form?

  Open

  Giant planets with orbits of weeks to months are too far out for tides to have circularized them yet too close to have formed where giants usually do. Unlike hot Jupiters, about half of them have small planets nearby, which hints at a gentler origin.