Kepler-277 c
Astrophysical Synthesis & Habitability Characterization
Kepler-277 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-277, located approximately 3185.4 light-years (976.64 parsecs) from the Solar System. First announced in 2013 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0332% across the stellar disk), this world measures 3.36 Earth radii (0.3 Jupiter radii) and has a measured mass of 64.2 Earth masses (0.2 Jupiter masses). Combining its mass and radius yields a mean bulk density of 9.33 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 5.69 g⊕ (55.8 m/s²), and an escape velocity of 48.9 km/s.
In its orbital architecture around Kepler-277, Kepler-277 c completes one full revolution every 33.006 Earth days at a semi-major axis of 0.21781 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 71.8 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 778 K (+505°C / +941°F) and receiving 83.90 S⊕ (~114,185 W/m²), Kepler-277 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-277 is classified as a stellar host with an effective photospheric temperature of 5,946 K, a radius of 1.69 R☉, a mass of 1.12 M☉, an estimated bolometric luminosity of 3.203 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.89 Gyr and a metallicity of [Fe/H] = 0.09 dex (metal-rich relative to the Sun). From Earth, Kepler-277 shines at apparent V-band magnitude 13.544 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-277 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-277 c sharing its stellar neighborhood alongside Kepler-277 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-277 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,946 K |
| Stellar Radius | 1.6900 R☉ |
| Stellar Mass | 1.1200 M☉ |
| Bolometric Luminosity | 3.203 L☉ |
| Metallicity [Fe/H] | 0.090 dex |
| Stellar Age | 3.890 Gyr |
| Apparent Magnitude | V: 13.544 · G: 13.388 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.217810 AU |
| Orbital Period | 33.006 days |
| Mean Orbital Velocity | 71.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.3300° |
| Mean Bulk Density | 9.33 g/cm³ (48.9 km/s vesc) |
| Insolation Flux | 83.8980 S⊕ (~114,185 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3185.400 LY (976.643 pc) |