14 Herculis c
Extrasolar planet in the constellation Hercules
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14 Herculis c or 14 Her c is the outermost of two known exoplanets orbiting the star 14 Herculis, approximately 58.4 light-years away in the constellation of Hercules. The planet has a mass that would make it a gas giant roughly the same size as Jupiter but much more massive.
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2 July 2021 (confirmed)
Direct image of 14 Herculis c taken with the James Webb Space Telescope. Its host star is blocked by a coronagraph. | |
| Discovery[1][2] | |
|---|---|
| Discovered by | Goździewski et al.; Rosenthal et al. |
| Discovery site | Observatoire de Haute-Provence,[3] Keck & AFP[2] |
| Discovery date | 17 November 2005 (candidate) 2 July 2021 (confirmed) |
| Doppler spectroscopy | |
| Designations | |
| HD 145675 c | |
| Orbital characteristics | |
| 20.0+12.0 â4.9 AU[4] 28.1+6.4 â6.8 AU[5] | |
| Eccentricity | 0.64+0.06 â0.10[5] |
| 52,160±1,030 days (142.8±2.8 years)[4] | |
| Inclination | 111.9°+5.4° â5.5°[5] |
| 205.1°+7.448° â10.31°[4] | |
| 2,451,779±33 JD[6] | |
| 172.5°+4.011° â4.584°[4] | |
| Semi-amplitude | 50.8±0.4 m/s[6] |
| Star | 14 Herculis |
| Physical characteristics[4] | |
| 1.03±0.01 RJ | |
| Mass | 7.9+1.6 â1.2 MJ |
| 4.25±0.15 cgs | |
| Temperature | 275 K (2 °C; 35 °F) |
Discovery
14 Herculis c was discovered by the radial velocity method. Its discovery was first reported in 2005 (published in 2006),[1] using data from the ELODIE Planet Search survey.[3] It remained a planet candidate until its existence was securely confirmed in 2021.[2]
According to a 2007 analysis, the existence of a second planet in the 14 Herculis system was "clearly" supported by the evidence, but the planet's parameters were not precisely known. It may be in a 4:1 resonance with the inner planet 14 Herculis b.[7]
The inclination and true mass of 14 Herculis c were measured in 2021, using data from Gaia,[8] and refined by further astrometric studies in 2022 and 2023,[9][6] as well by a 2025 study using James Webb Space Telescope astrometry. The inclination is 116°, corresponding to a true mass of 7.1 MJ.[6]
Direct imaging
The planet was directly imaged with the James Webb Space Telescope's NIRCam instrument in 2025. The observations determined a temperature of 275 K (2 °C), making it one of the coldest exoplanets directly imaged. They also re-measured its orbital elements, finding it to be closer to the star, at around 15 AU, on a highly eccentric orbit, as well as measuring its orbital inclination, finding it to be misaligned with 14 Herculis b by 40°. At wavelengths of 4.4 μm, its apparent magnitude is fainter than expected, hinting at disequilibrium chemistry and/or water ice clouds.[10][4]