 An artist's impression comparing the size and internal structure of Earth (left) and Kepler-93b (right). | |
| Discovery[1] | |
|---|---|
| Discovered by | Geoffrey W. Marcyet al. |
| Discovery date | February 2014 (announced) |
| Transit method | |
| Designations | |
| KIC 3544595 b,KOI-69.01,BD+38 3583b,TYC 3134-218-1 b[2] | |
| Orbital characteristics[3] | |
| 0.05343±0.00065 AU | |
| Eccentricity | 0 |
| 4.72673978(97) d | |
| Inclination | 89.183°±0.044° |
| Semi-amplitude | 1.89±0.21 m/s |
| Star | Kepler-93 |
| Physical characteristics[3] | |
| 1.478±0.019 R🜨 | |
| Mass | 4.66±0.53 M🜨 |
Meandensity | 7.93+0.96 −0.94 g/cm3 |
| Temperature | 1133±17 K (860 °C; 1,580 °F,equilibrium) |
Kepler-93b (KOI-69b) is a hot, densetransitingSuper-Earthexoplanet located approximately 313light-years (96parsecs)[4] away in theconstellation ofLyra,[5][6] orbiting theG-type star[5] Kepler-93. Its discovery was announced in February 2014 byAmerican astronomerGeoffrey Marcy and his team.[1] 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.[7]
The planet has a radius of around 1.478R🜨 (9,416km), with an uncertainty of just 0.019R🜨 (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 thanEarth at6.88±1.18 g/cm3[9] thanks to its high mass of roughly 4ME, consistent with a rocky composition ofiron andmagnesium silicate.[9] In 2023, the planet's mass was revised upward to 4.66±0.53ME, placing its density at 7.93+0.96
−0.94 g/cm3,[3] roughly the same as the metaliron (7.874 g/cm3).[10]
Based on these findings, the interior of the planet is likely similar to that of Earth andVenus, with an ironcore 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 ofMercury's orbit. Itsequilibrium temperature is approximately 1,133 K (860 °C; 1,580 °F),[3] which is as hot aslava and well above themelting point ofaluminium.[a]
The planet orbits aSun-like (spectral type G5V)[5] star named Kepler-93. The star has a mass of 0.911M☉ and a radius of 0.919R☉. 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] Theapparent 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 theradial-velocity method and announced in 2014, concurrently with Kepler-93b.[1] The object is most likely abrown 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 3MJ and a minimal orbital period of 1,460 days (4.0 years),[1] while a subsequent study in 2015 weighed the planet at >8.5MJ 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 >21MJ, an orbital period >48.6 years, and a semi-major axis >13 AU.[3]
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