Kepler-1625 is a Sun-like star, located in the constellation of Cygnus around 8,023 light years (2,460 parsecs) from Earth. In 2016, an extrasolar planet named Kepler-1625b was discovered orbiting the star. This gas giant planet orbits within the stars habitable zone. It was speculated that this planet might have an extrasolar moon, and, in October 2018, the discovery was announced. The possibility will be verified on October 29, 2018, the planet's next transit.
Characteristics[]
Kepler-1625 is a rather large star and is similar to the Sun. It has a radius 1.79 times that of the Sun, but is relatively close to the Sun's mass at just 1.079 Solar masses. Its temperature is 5,548 K, which is slightly lower than that of the Sun. These parameters suggest that Kepler-1625 might be a yellow sub-giant star that is nearing the end of its life. Kepler-1625 has a high metallicity of +0.12 dex. The star is around 8,023 light years (2,460 parsecs) away from Earth.
A secondary model for the size of Kepler-1625 puts the star at about 0.94 solar radii and 0.96 solar masses, with a temperature of 5677 K and a Sun-like metal content.
Planetary system[]
| Planet | Mass | Semimajor axis | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 10 Jupiter mass | 0.811 AU | 287.3789 days | N/A | 89.97° | 6-12 Earth radius |
The star currently has one confirmed planet, Kepler-1625b. The planet is notable because it is one of the best candidates for an exomoon. It orbits its star every 287.3 Earth days. The planets true size is currently unknown. Current models show that the radii should be slightly larger than Jupiter, at 12 Earth radii. However, if the smaller size estimate for the star is correct, then it the planet would actually be 6 Earth radii instead.
Exomoon[]
The light curves of the three observed planet transits suggests that an exomoon the size of Neptune is orbiting Kepler-1625b, with a separation of about 20 times the planetary radius. However, more confirmations are needed to confirm the existence of the moon. During the next planetary transit on October 29, the Hubble telescope will observe the star.