Kepler-16b

Kepler-16b was discovered in 2011 using the space observatory aboard NASA's Kepler spacecraft. Scientists were able to detect Kepler-16b using the transit method, when they noticed the dimming of one of the system's stars even when the other was not eclipsing it. Furthermore, duration of transits and timing all the eclipses and transits of Kepler-16b and its stars in the system has allowed for unusually high precision in the calculations of the sizes and masses of objects in the Kepler-16 system. The leader of Kepler-16b's discovery team, Laurance Doyle of the SETI Institute in Mountain View, California, said of this precision, "I believe this is the best-measured planet outside the solar system". For example, Kepler-16b's radius is known to within 0.3%, better than that of any other known exoplanet (as of September 2011). As seen from Earth, Kepler-16b ceased transiting the dimmer star in 2014, and stopped crossing the second, brighter star in 2018. After that, Kepler-16b will remain undetectable using the transit method until around 2042. In 2021, Kepler-16b became the first circumbinary planet to be detected by the radial velocity method. The second such planet was TOI-1338 c, discovered by this method in 2023. ==Characteristics==

Mass, radius and temperature Kepler-16b is a gas giant, an exoplanet that is near the same mass and radius as the planets Jupiter and Saturn. It has a temperature of . The planet has a radius of 0.77 , slightly smaller than Saturn, and has no solid surface. Host stars The planet orbits in a circumbinary orbit around a (K-type) and (M-type) binary star system. The stars orbit each other about every 41 days. The stars have masses of 0.68 and 0.20 and radii of 0.64 and 0.22 , respectively. They have surface temperatures of 4450 K and 3311 K and luminosities about 14% and 0.5% that of the Sun, respectively. Based on the stellar characteristics and orbital dynamics, an estimated age of 2 billion years for the system is possible. In comparison, the Sun is about 4.6 billion years old and has a surface temperature of 5778 K. Orbit Kepler-16b orbits its parent stars (more properly, their barycenter, or center of mass) every 228 days at a distance of 0.704 AU (nearly the same distance that Venus orbits from the Sun, which is about 0.71 AU). It is unlikely to have formed in its current orbit, and likely migrated from elsewhere. The small eccentricity of Kepler-16b's orbit remains unexplained. ==Potential habitability==

The habitable zone of the Kepler-16 system extends from approximately 55 to 106 million kilometers away from the binary system. Kepler-16b, with an orbit of about 104 million kilometers, lies near the outer edge of this habitable zone. Although the chances of life on the gas giant itself are remote, simulations conducted by researchers at the University of Texas suggest that sometime in the system's history, perturbations from other bodies could have caused an Earth-sized planet from the center of the habitable zone to migrate out of its orbit, allowing Kepler-16b to capture it as its moon. One way to decrease loss from sputtering is for the moon to have a strong magnetic field that can deflect stellar wind and radiation belts. NASA's Galileo's measurements hints large moons can have magnetic fields; it found that Jupiter's moon Ganymede has its own magnetosphere, even though its mass is only 0.025 . ==Name==

In the announcement paper, the discovery team stated: "Following the convention of Ref. 22, we can denote the third body Kepler-16 (AB)-b, or simply "b" when there is no ambiguity." It is listed as Kepler-16 (AB)-b on the SIMBAD Astronomical Database. The Extrasolar Planets Encyclopaedia lists it as Kepler-16 (AB) b. The Smithsonian Center has informally referred to Kepler-16b as "Tatooine", a reference to the fictional planet orbiting two suns that is a key setting in the popular Star Wars series. "Again and again we see that the science is stranger and weirder than fiction" said John Knoll, the head visual effects supervisor at Industrial Light & Magic, who worked on several of the movies. ==Gallery==