The planet has a radius of around 1.478 R🜨 (9,416 km), with an uncertainty of just 0.019 R🜨 (121 km),[8] making it the most precisely measured exoplanet ever in terms of radius as of July 2014.[7] The planet is substantially denser than Earth at 6.88±1.18 g/cm3[9] thanks to its high mass of roughly 4 M🜨, consistent with a rocky composition of iron and magnesium silicate.[9] In 2023, the planet's mass was revised upward to 4.66±0.53 M🜨, placing its density at 7.93+0.96 −0.94 g/cm3,[3] roughly the same as the metal iron (7.874 g/cm3).[10]
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%),[11] compared to the 32.5 ± 0.1% of Earth and 31 ± 1% of Venus.[11]
The planet orbits its host star every 4.73 days[8] at a distance of 0.05343 AU (7,993,000 km),[3] less than one-seventh the radius of Mercury's orbit. Its equilibrium temperature is approximately 1,133 K (860 °C; 1,580 °F),[3] which is as hot as lava and well above the melting point of aluminium.[a]
Host star
The planet orbits a Sun-like (spectral type G5V)[5] star named Kepler-93. The star has a mass of 0.911 M☉ and a radius of 0.919 R☉. It has a temperature of 5,669 K (5,396 °C; 9,745 °F) and is 6.6 billion years old.[8] In comparison, the Sun is 4.6 billion years old,[14] has a temperature of 5,772 K (5,499 °C; 9,930 °F) and a spectral type of G2V.[15] The apparent magnitude of the star is 9.931,[9] making it too dim to be visible from Earth by the naked eye.[16]
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.[1] 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 MJ and a minimal orbital period of 1,460 days (4.0 years),[1] while a subsequent study in 2015 weighed the planet at >8.5 MJ and presented an orbital period of >10 years, placing its orbit beyond 4.5 AU from the star,[9] and a 2023 study increased these lower limits further, to a mass >21 MJ, an orbital period >48.6 years, and a semi-major axis >13 AU.[3]
^Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN978-1-62708-155-9.
^Philpotts, Anthony R.; Ague, Jay J. (2009). Principles of igneous and metamorphic petrology (2nd ed.). Cambridge, UK: Cambridge University Press. pp. 53–55. ISBN9780521880060.
