Kepler-1085 c
Astrophysical Synthesis & Habitability Characterization
Kepler-1085 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-1085, located approximately 4450.5 light-years (1364.53 parsecs) from the Solar System. First announced in 2020 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0772% across the stellar disk), this world measures 3.268 Earth radii (0.29 Jupiter radii) and has a measured mass of 10.7 Earth masses. Combining its mass and radius yields a mean bulk density of 1.69 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1 g⊕ (9.81 m/s²), and an escape velocity of 20.2 km/s.
In its orbital architecture around Kepler-1085, Kepler-1085 c completes one full revolution every 56.777 Earth days at a semi-major axis of 0.29798 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 57.1 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 491 K (+218°C / +424°F) and receiving 11.80 S⊕ (~16,060 W/m²), Kepler-1085 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1085 is classified as a stellar host with an effective photospheric temperature of 5,816 K, a radius of 1.0783 R☉, a mass of 1.05 M☉, an estimated bolometric luminosity of 1.194 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.07 Gyr and a metallicity of [Fe/H] = 0.22 dex (metal-rich relative to the Sun). From Earth, Kepler-1085 shines at apparent V-band magnitude 15.273 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-1085 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-1085 c sharing its stellar neighborhood alongside Kepler-1085 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-1085 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,816 K |
| Stellar Radius | 1.0783 R☉ |
| Stellar Mass | 1.0500 M☉ |
| Bolometric Luminosity | 1.194 L☉ |
| Metallicity [Fe/H] | 0.220 dex |
| Stellar Age | 1.070 Gyr |
| Apparent Magnitude | V: 15.273 · G: 15.247 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.297980 AU |
| Orbital Period | 56.777 days |
| Mean Orbital Velocity | 57.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.1500° |
| Mean Bulk Density | 1.69 g/cm³ (20.2 km/s vesc) |
| Insolation Flux | 11.8000 S⊕ (~16,060 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 4450.500 LY (1364.530 pc) |