Kepler-419c
Super-Jupiter in the habitable zone, discovered via transit timing variations.
Kepler-419c, also cataloged as KOI-1474.02, is a super-Jupiter exoplanet that orbits within the habitable zone of its host star, Kepler-419. It is the outermost of two planets found by NASA’s Kepler spacecraft, located roughly 3,400 light-years away in the constellation Cygnus. Astronomers detected it using the transit timing variation method, which tracks small shifts in a known planet’s transit data to uncover a more distant companion.
This planet is a super-Jupiter, meaning its mass and radius exceed those of Jupiter. Its equilibrium temperature is about 250 K, slightly cooler than Earth’s. Kepler-419c has a mass of 7.2 times that of Jupiter, and based on that mass, its radius is likely around 1.13 times Jupiter’s.
The host star, Kepler-419, is an F-type star with a mass of 1.39 times the Sun’s and a radius of 1.75 times the Sun’s. Its surface temperature is 6430 K, and it is about 2.8 billion years old—younger than the Sun, which is 4.6 billion years old and has a surface temperature of 5778 K. The star’s apparent magnitude is 12, making it too faint to see without a telescope.
Kepler-419c orbits its star at a distance of 1.61 AU—slightly farther than Mars’s orbit of 1.52 AU—and completes one orbit every 675 days (about 1.84 years). The star’s luminosity is 2.7 times that of the Sun. The planet’s orbit is slightly elliptical, with an eccentricity of 0.184, and it receives about 95% of the sunlight Earth gets.
Because Kepler-419c lies within the circumstellar habitable zone, it is considered a candidate for hosting potentially habitable moons. The planet itself, at 7.28 Jupiter masses, is too massive to be rocky and is likely not habitable. However, with the right atmospheric pressure and temperature, liquid water could exist on the surface of a hypothetical moon. For a moon to remain in a stable orbit, its orbital period around the planet must be less than one-ninth of the planet’s orbital period around the star. In this case, a moon with an orbital period shorter than about 65 days would likely stay bound to the planet.
Kepler-419c was discovered after NASA’s Kepler spacecraft, which began observing stars in 2009 using its photometer to detect transits, collected data on the star Kepler-419. Preliminary light curves were sent to the Kepler science team, who identified promising planetary candidates for follow-up.
Quick Facts
- Discoverer
- Kepler spacecraft
- Discovered
- 12 June 2014
- Discovery Method
- Transit timing variations
- Apsis
- astron
- Semimajor
- 1.68 (± 0.03) AU
- Eccentricity
- 0.184 (± 0.002)
- Period
- 675.47 (± 0.11) d
- Inclination
- 88 · 3 · 2
- Star
- Kepler-419 (KOI-1474)
- Single Temperature
- 250 K
Facts from the source article.
Lore & Background
Kepler-419c is a super-Jupiter, an exoplanet with a radius and mass greater than that of Jupiter. It has a temperature of 250 K, somewhat cooler than Earth's equilibrium temperature. Its mass is 7.2 Jupiter masses, and its likely radius is around 1.13 Jupiter radii, based on its high mass. The planet orbits an F-type star named Kepler-419, which has a mass of 1.39 solar masses, a radius of 1.75 solar radii, a surface temperature of 6430 K, and an age of 2.8 billion years. The star's apparent magnitude is 12, too dim to be seen with the naked eye.
Kepler-419c orbits its host star with 270% of the Sun's luminosity every 675 days at a distance of 1.61 AU, slightly farther than Mars's orbital distance of 1.52 AU. It has a slightly eccentric orbit with an eccentricity of 0.184 and receives about 95% of the sunlight that Earth does. The planet resides in the circumstellar habitable zone of its parent star, but with a mass of 7.28 Jupiter masses it is too massive to be rocky and is probably not habitable itself. However, it is listed as a candidate that may harbor potentially habitable moons, where, with the right atmospheric pressure and temperature, liquid water might exist on the moon's surface.
Hypothetically, for a stable orbit the ratio between a moon's orbital period around its primary and that of the primary around its star must be less than 1/9. Simulations suggest a moon with an orbital period less than about 45 to 60 days will remain safely bound to a massive giant planet orbiting 1 AU from a Sun-like star. In the case of Kepler-419c, this would be practically the same, albeit a bit longer, around 65 days.
Reader's Guide
Kepler-419c is notable as a super-Jupiter discovered through the transit timing variation method, which revealed its presence by analyzing variations in the transit data of the inner planet Kepler-419b. This technique allowed astronomers to detect a more distant companion that does not transit its star directly. The planet's location within the circumstellar habitable zone of its F-type host star makes it a candidate for potentially habitable moons, a concept explored through simulations of stable moon orbits. Its mass of 7.2 Jupiter masses and radius of about 1.13 Jupiter radii place it firmly in the super-Jupiter category, while its orbital period of 675 days and eccentricity of 0.184 provide a distinct orbital profile. The discovery was announced on June 12, 2014, following observations between May 13, 2009, and March 17, 2012, as part of NASA's Kepler mission. Kepler-419c contributes to the understanding of planetary systems with multiple planets and the potential for exomoons in habitable zones, expanding the search for environments that could support liquid water beyond Earth.
Did You Know?
- Kepler-419c was discovered using the transit timing variation method, not direct transit detection.
- It has a mass of 7.2 Jupiter masses and a likely radius of about 1.13 Jupiter radii.
More in Transiting Exoplanets, Part 2 1-24
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