Kepler-377 c
Astrophysical Synthesis & Habitability Characterization
Kepler-377 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-377, located approximately 2686.9 light-years (823.8 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0238% across the stellar disk), this world measures 2.06 Earth radii and has a measured mass of 4.9 Earth masses. Combining its mass and radius yields a mean bulk density of 3.09 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.15 g⊕ (11.28 m/s²), and an escape velocity of 17.3 km/s.
In its orbital architecture around Kepler-377, Kepler-377 c completes one full revolution every 27.015 Earth days at a semi-major axis of 0.182 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 73.3 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 677 K (+404°C / +759°F) and receiving 49.86 S⊕ (~67,853 W/m²), Kepler-377 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-377 is classified as a stellar host with an effective photospheric temperature of 5,949 K, a radius of 1.224 R☉, a mass of 1.043 M☉, an estimated bolometric luminosity of 1.684 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.5 Gyr and a metallicity of [Fe/H] = 0.05 dex (near-solar heavy-element abundance). From Earth, Kepler-377 shines at apparent V-band magnitude 14.081 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-377 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-377 c sharing its stellar neighborhood alongside Kepler-377 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-377 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,949 K |
| Stellar Radius | 1.2240 R☉ |
| Stellar Mass | 1.0430 M☉ |
| Bolometric Luminosity | 1.684 L☉ |
| Metallicity [Fe/H] | 0.050 dex |
| Stellar Age | 5.500 Gyr |
| Apparent Magnitude | V: 14.081 · G: 13.832 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.182000 AU |
| Orbital Period | 27.015 days |
| Mean Orbital Velocity | 73.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9900° |
| Mean Bulk Density | 3.09 g/cm³ (17.3 km/s vesc) |
| Insolation Flux | 49.8550 S⊕ (~67,853 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2686.900 LY (823.804 pc) |