Kepler-1873 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1873 b is a confirmed super-earth exoplanet orbiting the star Kepler-1873, located approximately 2677.6 light-years (820.96 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0354% across the stellar disk), this world measures 1.626 Earth radii and has a measured mass of 3.28 Earth masses. Combining its mass and radius yields a mean bulk density of 4.21 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.24 g⊕ (12.16 m/s²), and an escape velocity of 15.9 km/s.
In its orbital architecture around Kepler-1873, Kepler-1873 b completes one full revolution every 0.559 Earth days at a semi-major axis of 0.0128 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 249.2 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 1787 K (+1514°C / +2757°F) and receiving 2,412.15 S⊕ (~3,282,936 W/m²), Kepler-1873 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1873 is classified as a stellar host with an effective photospheric temperature of 5,151 K, a radius of 0.792 R☉, a mass of 0.903 M☉, an estimated bolometric luminosity of 0.396 L☉. Stellar evolution modeling indicates an estimated stellar age of 1 Gyr and a metallicity of [Fe/H] = 0.21 dex (metal-rich relative to the Sun). From Earth, Kepler-1873 shines at apparent V-band magnitude 15.889 (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-1873 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,151 K |
| Stellar Radius | 0.7920 R☉ |
| Stellar Mass | 0.9030 M☉ |
| Bolometric Luminosity | 0.396 L☉ |
| Metallicity [Fe/H] | 0.210 dex |
| Stellar Age | 1.000 Gyr |
| Apparent Magnitude | V: 15.889 · G: 15.610 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.012800 AU |
| Orbital Period | 0.559 days |
| Mean Orbital Velocity | 249.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 86.6500° |
| Mean Bulk Density | 4.21 g/cm³ (15.9 km/s vesc) |
| Insolation Flux | 2412.1500 S⊕ (~3,282,936 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2677.600 LY (820.957 pc) |