| Kepler-93b | |
| Discoverer: | Geoffrey W. Marcy et al. |
| Discovered: | February 2014 (announced) |
| Discovery Method: | Transit method |
| Alt Names: | KIC 3544595 b, KOI-69.01, BD+38 3583b, TYC 3134-218-1 b[1] |
| Apsis: | astron |
| Eccentricity: | 0 |
| Star: | Kepler-93 |
| Single Temperature: | (1133K, equilibrium) |
Kepler-93b (KOI-69b) is a hot, dense transiting Super-Earth exoplanet located approximately 313lk=onNaNlk=on away in the constellation of Lyra,[2] [3] orbiting the G-type star[2] Kepler-93. Its discovery was announced in February 2014 by American astronomer Geoffrey Marcy and his team. In July 2014, its radius was determined with a mere 1.3% margin of error, the most precise measurement ever made for an exoplanet's radius at the time.
The planet has a radius of around 1.478 (9,416 km), with an uncertainty of just 0.019 (121 km), making it the most precisely measured exoplanet ever in terms of radius as of July 2014.[4] The planet is substantially denser than Earth at thanks to its high mass of roughly 4, consistent with a rocky composition of iron and magnesium silicate. In 2023, the planet's mass was revised upward to 4.66, placing its density at 7.93 g/cm3, roughly the same as the metal iron .[5]
Based on these findings, the interior of the planet is likely similar to that of Earth and Venus, with an iron core making up around 26% of its total mass (albeit with a large uncertainty of ±20%), compared to the 32.5 ± 0.1% of Earth and 31 ± 1% of Venus.[6]
The planet orbits its host star every 4.73 days at a distance of 0.05343AU, less than one-seventh the radius of Mercury's orbit. Its equilibrium temperature is approximately 1133K, which is as hot as lava and well above the melting point of aluminium.
The planet orbits a Sun-like (spectral type G5V)[2] star named Kepler-93. The star has a mass of 0.911 and a radius of 0.919 . It has a temperature of 5669K and is 6.6 billion years old. In comparison, the Sun is 4.6 billion years old,[7] has a temperature of 5772K and a spectral type of G2V.[8] The apparent magnitude of the star is 9.931, making it too dim to be visible from Earth by the naked eye.[9]
The star is host to an additional non-transiting confirmed companion, Kepler-93c, which was discovered using the radial-velocity method and announced in 2014, concurrently with Kepler-93b. The object is most likely a brown dwarf orbiting much farther out than Kepler-93b, though its precise nature remains uncertain. The discovery paper reported a lower limit on the mass of 3 and a minimal orbital period of 1460d, while a subsequent study in 2015 weighed the planet at >8.5 and presented an orbital period of >10 years, placing its orbit beyond 4.5 AU from the star, and a 2023 study increased these lower limits further, to a mass >21, an orbital period >48.6 years, and a semi-major axis >13 AU.