HAT-P-13

HAT-P-13 is a star system approximately 697 light-years away in the constellation Ursa Major. It consists of a star, HAT-P-13, and at least two planets: HAT-P-13b and HAT-P-13c.

HAT-P-13 (Star): This is a G4V-type star, a main-sequence star similar to our Sun, but slightly cooler and less massive. It has a mass of about 1.22 solar masses and a radius of about 1.52 solar radii.

HAT-P-13b: This is a transiting exoplanet, also designated WASP-22b. It is a hot Jupiter, a gas giant planet that orbits very close to its star. It was discovered in 2009 by the HATNet project using the transit method. It has a mass of approximately 0.85 Jupiter masses and a radius of about 1.21 Jupiter radii. Its orbital period is about 2.9 days, making it a very hot planet with an estimated equilibrium temperature of over 1700 K.

HAT-P-13c: This is a more distant, non-transiting planet in the system, discovered through radial velocity measurements. It is a gas giant with a significantly longer orbital period of approximately 446 days and a higher eccentricity compared to HAT-P-13b. Its mass is estimated to be around 15 Jupiter masses. The gravitational influence of HAT-P-13c on HAT-P-13b allows astronomers to study the system's dynamics and potentially determine the planet's true mass, which is sometimes difficult to ascertain via the radial velocity method alone due to orbital inclination uncertainties.

The HAT-P-13 system is of interest to astronomers because the presence of two giant planets makes it a relatively rare and valuable system for studying planetary dynamics and the formation and evolution of planetary systems. The interaction between HAT-P-13b and HAT-P-13c provides insights into planetary migration and orbital stability in multi-planet systems.