Kepler-177 c
Astrophysical Synthesis & Habitability Characterization
Kepler-177 c is a confirmed gas giant exoplanet orbiting the star Kepler-177, located approximately 4681.8 light-years (1435.44 parsecs) from the Solar System. First announced in 2013 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.3654% across the stellar disk), this world measures 8.73 Earth radii (0.78 Jupiter radii) and has a measured mass of 14.7 Earth masses. Combining its mass and radius yields a mean bulk density of 0.12 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.19 g⊕ (1.86 m/s²), and an escape velocity of 14.5 km/s.
In its orbital architecture around Kepler-177, Kepler-177 c completes one full revolution every 49.409 Earth days at a semi-major axis of 0.25655 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 56.5 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 497 K (+224°C / +435°F) and receiving 25.40 S⊕ (~34,569 W/m²), Kepler-177 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-177 is classified as a stellar host with an effective photospheric temperature of 5,732 K, a radius of 1.324 R☉, a mass of 0.921 M☉, an estimated bolometric luminosity of 1.698 L☉. Stellar evolution modeling indicates an estimated stellar age of 11.75 Gyr and a metallicity of [Fe/H] = -0.11 dex (metal-poor relative to the Sun). From Earth, Kepler-177 shines at apparent V-band magnitude 15.171 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-177 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-177 c sharing its stellar neighborhood alongside Kepler-177 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: Kepler · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | Kepler-177 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,732 K |
| Stellar Radius | 1.3240 R☉ |
| Stellar Mass | 0.9210 M☉ |
| Bolometric Luminosity | 1.698 L☉ |
| Metallicity [Fe/H] | -0.110 dex |
| Stellar Age | 11.750 Gyr |
| Apparent Magnitude | V: 15.171 · G: 14.941 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.256550 AU |
| Orbital Period | 49.409 days |
| Mean Orbital Velocity | 56.5 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.7950° |
| Mean Bulk Density | 0.12 g/cm³ (14.5 km/s vesc) |
| Insolation Flux | 25.4000 S⊕ (~34,569 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 4681.800 LY (1435.440 pc) |