Kepler-653 c
Astrophysical Synthesis & Habitability Characterization
Kepler-653 c is a confirmed sub-earth exoplanet orbiting the star Kepler-653, located approximately 1942.7 light-years (595.63 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0036% across the stellar disk), this world measures 0.78 Earth radii and has a measured mass of 0.399 Earth masses. Combining its mass and radius yields a mean bulk density of 4.64 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 0.66 g⊕ (6.47 m/s²), and an escape velocity of 8 km/s.
In its orbital architecture around Kepler-653, Kepler-653 c completes one full revolution every 0.9 Earth days at a semi-major axis of 0.01855 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 224.1 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 2078 K (+1805°C / +3281°F) and receiving 3,743.28 S⊕ (~5,094,597 W/m²), Kepler-653 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-653 is classified as a stellar host with an effective photospheric temperature of 5,665 K, a radius of 1.19 R☉, a mass of 1.02 M☉, an estimated bolometric luminosity of 1.309 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.76 Gyr and a metallicity of [Fe/H] = 0.23 dex (metal-rich relative to the Sun). From Earth, Kepler-653 shines at apparent V-band magnitude 13.498 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-653 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-653 c sharing its stellar neighborhood alongside Kepler-653 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-653 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,665 K |
| Stellar Radius | 1.1900 R☉ |
| Stellar Mass | 1.0200 M☉ |
| Bolometric Luminosity | 1.309 L☉ |
| Metallicity [Fe/H] | 0.230 dex |
| Stellar Age | 7.760 Gyr |
| Apparent Magnitude | V: 13.498 · G: 13.346 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.018550 AU |
| Orbital Period | 0.9 days |
| Mean Orbital Velocity | 224.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.0400° |
| Mean Bulk Density | 4.64 g/cm³ (8 km/s vesc) |
| Insolation Flux | 3743.2750 S⊕ (~5,094,597 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1942.700 LY (595.634 pc) |