Kepler-1871 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1871 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1871, located approximately 2787.4 light-years (854.62 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0551% across the stellar disk), this world measures 2.422 Earth radii and has a measured mass of 6.44 Earth masses. Combining its mass and radius yields a mean bulk density of 2.5 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.1 g⊕ (10.79 m/s²), and an escape velocity of 18.2 km/s.
In its orbital architecture around Kepler-1871, Kepler-1871 b completes one full revolution every 1.953 Earth days at a semi-major axis of 0.0308 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 171.6 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 1403 K (+1130°C / +2066°F) and receiving 917.15 S⊕ (~1,248,241 W/m²), Kepler-1871 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1871 is classified as a stellar host with an effective photospheric temperature of 5,741 K, a radius of 0.946 R☉, a mass of 1.02 M☉, an estimated bolometric luminosity of 0.872 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.7 Gyr and a metallicity of [Fe/H] = 0.12 dex (metal-rich relative to the Sun). From Earth, Kepler-1871 shines at apparent V-band magnitude 14.822 (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-1871 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,741 K |
| Stellar Radius | 0.9460 R☉ |
| Stellar Mass | 1.0200 M☉ |
| Bolometric Luminosity | 0.872 L☉ |
| Metallicity [Fe/H] | 0.120 dex |
| Stellar Age | 5.700 Gyr |
| Apparent Magnitude | V: 14.822 · G: 14.544 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.030800 AU |
| Orbital Period | 1.953 days |
| Mean Orbital Velocity | 171.6 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 80.9600° |
| Mean Bulk Density | 2.5 g/cm³ (18.2 km/s vesc) |
| Insolation Flux | 917.1500 S⊕ (~1,248,241 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2787.400 LY (854.623 pc) |