Kepler-1531 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1531 b is a confirmed terrestrial exoplanet orbiting the star Kepler-1531, located approximately 2173.3 light-years (666.33 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0064% across the stellar disk), this world measures 1.11 Earth radii and has a measured mass of 1.41 Earth masses. Combining its mass and radius yields a mean bulk density of 5.68 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.14 g⊕ (11.18 m/s²), and an escape velocity of 12.6 km/s.
In its orbital architecture around Kepler-1531, Kepler-1531 b completes one full revolution every 1.139 Earth days at a semi-major axis of 0.02204 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 210.6 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 2537 K (+2264°C / +4107°F) and receiving 4,457.20 S⊕ (~6,066,249 W/m²), Kepler-1531 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1531 is classified as a stellar host with an effective photospheric temperature of 6,260 K, a radius of 1.27 R☉, a mass of 1.16 M☉, an estimated bolometric luminosity of 2.222 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.82 Gyr and a metallicity of [Fe/H] = -0.03 dex (near-solar heavy-element abundance). From Earth, Kepler-1531 shines at apparent V-band magnitude 13.202 (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-1531 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,260 K |
| Stellar Radius | 1.2700 R☉ |
| Stellar Mass | 1.1600 M☉ |
| Bolometric Luminosity | 2.222 L☉ |
| Metallicity [Fe/H] | -0.030 dex |
| Stellar Age | 2.820 Gyr |
| Apparent Magnitude | V: 13.202 · G: 13.171 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.022040 AU |
| Orbital Period | 1.139 days |
| Mean Orbital Velocity | 210.6 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 81.0700° |
| Mean Bulk Density | 5.68 g/cm³ (12.6 km/s vesc) |
| Insolation Flux | 4457.2000 S⊕ (~6,066,249 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2173.300 LY (666.334 pc) |