Kepler-1656 c
Astrophysical Synthesis & Habitability Characterization
Kepler-1656 c is a confirmed gas giant exoplanet orbiting the star Kepler-1656, located approximately 606.2 light-years (185.88 parsecs) from the Solar System. First announced in 2022 by W. M. Keck Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 14 Earth radii (1.25 Jupiter radii) and has a measured mass of 126.4 Earth masses (0.4 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.25 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.64 g⊕ (6.28 m/s²), and an escape velocity of 33.6 km/s.
In its orbital architecture around Kepler-1656, Kepler-1656 c completes one full revolution every 1919 Earth days (5.25Julian years) at a semi-major axis of 3.053 AU (corresponding to the middle-system regime between Mars at 1.52 AU and Jupiter at 5.20 AU). Its mean orbital velocity is approximately 17.3 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.527, swinging from 1.4441 AU at periapsis out to 4.6619 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 161 K (-112°C / -170°F) and an incident flux of 0.11 S⊕ (~153 W/m²), surface water and volatile species on Kepler-1656 c would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star Kepler-1656 is classified as a stellar host with an effective photospheric temperature of 5,569 K, a radius of 1.1 R☉, a mass of 1.03 M☉, an estimated bolometric luminosity of 1.044 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.31 Gyr and a metallicity of [Fe/H] = 0.19 dex (metal-rich relative to the Sun). From Earth, Kepler-1656 shines at apparent V-band magnitude 11.64 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-1656 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-1656 c sharing its stellar neighborhood alongside Kepler-1656 b.
Methodology: Computed using the Schulze-Makuch et al. (2011) weighted metric comparing physical interior (radius, estimated density) and surface thermal regime (escape velocity, equilibrium temperature).
Discovery Facility: W. M. Keck Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | Kepler-1656 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,569 K |
| Stellar Radius | 1.1000 R☉ |
| Stellar Mass | 1.0300 M☉ |
| Bolometric Luminosity | 1.044 L☉ |
| Metallicity [Fe/H] | 0.190 dex |
| Stellar Age | 6.310 Gyr |
| Apparent Magnitude | V: 11.640 · G: 11.062 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 3.053000 AU |
| Orbital Period | 1919 days |
| Mean Orbital Velocity | 17.3 km/s |
| Orbital Eccentricity (e) | 0.52700 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.25 g/cm³ (33.6 km/s vesc) |
| Insolation Flux | 0.1126 S⊕ (~153 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 606.200 LY (185.875 pc) |