Kepler-243 b
Astrophysical Synthesis & Habitability Characterization
Kepler-243 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-243, located approximately 2263.1 light-years (693.86 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0712% across the stellar disk), this world measures 2.45 Earth radii and has a measured mass of 6.57 Earth masses. Combining its mass and radius yields a mean bulk density of 2.46 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.09 g⊕ (10.69 m/s²), and an escape velocity of 18.3 km/s.
In its orbital architecture around Kepler-243, Kepler-243 b completes one full revolution every 5.715 Earth days at a semi-major axis of 0.062 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 118 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 850 K (+577°C / +1071°F) and receiving 115.51 S⊕ (~157,202 W/m²), Kepler-243 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-243 is classified as a stellar host with an effective photospheric temperature of 5,228 K, a radius of 0.842 R☉, a mass of 0.904 M☉, an estimated bolometric luminosity of 0.475 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.86 Gyr and a metallicity of [Fe/H] = 0.26 dex (metal-rich relative to the Sun). From Earth, Kepler-243 shines at apparent V-band magnitude 15.159 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-243 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-243 b sharing its stellar neighborhood alongside Kepler-243 c.
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-243 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,228 K |
| Stellar Radius | 0.8420 R☉ |
| Stellar Mass | 0.9040 M☉ |
| Bolometric Luminosity | 0.475 L☉ |
| Metallicity [Fe/H] | 0.260 dex |
| Stellar Age | 1.860 Gyr |
| Apparent Magnitude | V: 15.159 · G: 15.057 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.062000 AU |
| Orbital Period | 5.715 days |
| Mean Orbital Velocity | 118 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.8100° |
| Mean Bulk Density | 2.46 g/cm³ (18.3 km/s vesc) |
| Insolation Flux | 115.5050 S⊕ (~157,202 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2263.100 LY (693.860 pc) |