Kepler-242 b
Astrophysical Synthesis & Habitability Characterization
Kepler-242 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-242, located approximately 1957.7 light-years (600.24 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0792% across the stellar disk), this world measures 2.61 Earth radii and has a measured mass of 7.32 Earth masses. Combining its mass and radius yields a mean bulk density of 2.27 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.07 g⊕ (10.49 m/s²), and an escape velocity of 18.7 km/s.
In its orbital architecture around Kepler-242, Kepler-242 b completes one full revolution every 8.204 Earth days at a semi-major axis of 0.075 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 99.5 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 742 K (+469°C / +876°F) and receiving 43.77 S⊕ (~59,568 W/m²), Kepler-242 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-242 is classified as a stellar host with an effective photospheric temperature of 5,020 K, a radius of 0.85 R☉, a mass of 0.748 M☉, an estimated bolometric luminosity of 0.412 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.69 Gyr and a metallicity of [Fe/H] = -0.02 dex (near-solar heavy-element abundance). From Earth, Kepler-242 shines at apparent V-band magnitude 15.489 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-242 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-242 b sharing its stellar neighborhood alongside Kepler-242 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-242 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,020 K |
| Stellar Radius | 0.8500 R☉ |
| Stellar Mass | 0.7480 M☉ |
| Bolometric Luminosity | 0.412 L☉ |
| Metallicity [Fe/H] | -0.020 dex |
| Stellar Age | 2.690 Gyr |
| Apparent Magnitude | V: 15.489 · G: 15.349 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.075000 AU |
| Orbital Period | 8.204 days |
| Mean Orbital Velocity | 99.5 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 86.4300° |
| Mean Bulk Density | 2.27 g/cm³ (18.7 km/s vesc) |
| Insolation Flux | 43.7680 S⊕ (~59,568 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1957.700 LY (600.241 pc) |