Kepler-1171 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1171 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1171, located approximately 1868.9 light-years (573 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0145% across the stellar disk), this world measures 2.56 Earth radii and has a measured mass of 7.08 Earth masses. Combining its mass and radius yields a mean bulk density of 2.33 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.08 g⊕ (10.59 m/s²), and an escape velocity of 18.6 km/s.
In its orbital architecture around Kepler-1171, Kepler-1171 b completes one full revolution every 1.443 Earth days at a semi-major axis of 0.0284 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 214.2 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 2700 K (+2427°C / +4401°F) and receiving 10,171.01 S⊕ (~13,842,738 W/m²), Kepler-1171 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1171 is classified as a stellar host with an effective photospheric temperature of 7,044 K, a radius of 1.95 R☉, a mass of 1.58 M☉, an estimated bolometric luminosity of 8.399 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.35 Gyr and a metallicity of [Fe/H] = -0.01 dex (near-solar heavy-element abundance). From Earth, Kepler-1171 shines at apparent V-band magnitude 11.647 (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-1171 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 7,044 K |
| Stellar Radius | 1.9500 R☉ |
| Stellar Mass | 1.5800 M☉ |
| Bolometric Luminosity | 8.399 L☉ |
| Metallicity [Fe/H] | -0.010 dex |
| Stellar Age | 1.350 Gyr |
| Apparent Magnitude | V: 11.647 · G: 11.459 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.028400 AU |
| Orbital Period | 1.443 days |
| Mean Orbital Velocity | 214.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 86.8200° |
| Mean Bulk Density | 2.33 g/cm³ (18.6 km/s vesc) |
| Insolation Flux | 10171.0050 S⊕ (~13,842,738 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1868.900 LY (573.000 pc) |