Kepler-1646 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1646 b is a confirmed terrestrial exoplanet orbiting the star Kepler-1646, located approximately 416.1 light-years (127.59 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1881% across the stellar disk), this world measures 1.23 Earth radii and has a measured mass of 2.04 Earth masses. Combining its mass and radius yields a mean bulk density of 6.04 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.35 g⊕ (13.24 m/s²), and an escape velocity of 14.4 km/s.
In its orbital architecture around Kepler-1646, Kepler-1646 b completes one full revolution every 4.486 Earth days at a semi-major axis of 0.0295 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 71.5 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 365 K (+92°C / +198°F) and receiving 4.20 S⊕ (~5,716 W/m²), Kepler-1646 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1646 is classified as a stellar host with an effective photospheric temperature of 3,299 K, a radius of 0.26 R☉, a mass of 0.24 M☉, an estimated bolometric luminosity of 0.00718 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.68 Gyr and a metallicity of [Fe/H] = 0.04 dex (near-solar heavy-element abundance). From Earth, Kepler-1646 shines at apparent V-band magnitude 16.842 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.
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-1646 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 3,299 K |
| Stellar Radius | 0.2600 R☉ |
| Stellar Mass | 0.2400 M☉ |
| Bolometric Luminosity | 0.00718 L☉ |
| Metallicity [Fe/H] | 0.040 dex |
| Stellar Age | 4.680 Gyr |
| Apparent Magnitude | V: 16.842 · G: 15.655 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.029500 AU |
| Orbital Period | 4.486 days |
| Mean Orbital Velocity | 71.5 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.3600° |
| Mean Bulk Density | 6.04 g/cm³ (14.4 km/s vesc) |
| Insolation Flux | 4.2000 S⊕ (~5,716 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 416.100 LY (127.591 pc) |