Kepler-37 e
Astrophysical Synthesis & Habitability Characterization
Kepler-37 e is a confirmed sub-earth exoplanet orbiting the star Kepler-37, located approximately 208.5 light-years (63.92 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0019% across the stellar disk), this world measures 0.37 Earth radii and has a measured mass of 8.1 Earth masses. Combining its mass and radius yields a mean bulk density of 881.75 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 59.17 g⊕ (580.26 m/s²), and an escape velocity of 52.3 km/s.
In its orbital architecture around Kepler-37, Kepler-37 e completes one full revolution every 51.196 Earth days at a semi-major axis of 0.25 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 53.1 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 401 K (+128°C / +262°F) and receiving 7.63 S⊕ (~10,378 W/m²), Kepler-37 e orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-37 is classified as a stellar host with an effective photospheric temperature of 5,288 K, a radius of 0.772 R☉, a mass of 0.8 M☉, an estimated bolometric luminosity of 0.418 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.8 Gyr and a metallicity of [Fe/H] = -0.25 dex (metal-poor relative to the Sun). From Earth, Kepler-37 shines at apparent V-band magnitude 9.77 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The Kepler-37 system is a multi-planet architecture hosting 4 confirmed worlds, with Kepler-37 e sharing its stellar neighborhood alongside Kepler-37 b, Kepler-37 c, Kepler-37 d.
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-37 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,288 K |
| Stellar Radius | 0.7720 R☉ |
| Stellar Mass | 0.8000 M☉ |
| Bolometric Luminosity | 0.418 L☉ |
| Metallicity [Fe/H] | -0.250 dex |
| Stellar Age | 3.800 Gyr |
| Apparent Magnitude | V: 9.770 · G: 9.550 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.250000 AU |
| Orbital Period | 51.196 days |
| Mean Orbital Velocity | 53.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9500° |
| Mean Bulk Density | 881.75 g/cm³ (52.3 km/s vesc) |
| Insolation Flux | 7.6252 S⊕ (~10,378 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 208.500 LY (63.921 pc) |