Kepler-342 d
Astrophysical Synthesis & Habitability Characterization
Kepler-342 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-342, located approximately 2549.3 light-years (781.61 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0241% across the stellar disk), this world measures 2.49 Earth radii and has a measured mass of 6.76 Earth masses. Combining its mass and radius yields a mean bulk density of 2.41 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 18.4 km/s.
In its orbital architecture around Kepler-342, Kepler-342 d completes one full revolution every 39.459 Earth days at a semi-major axis of 0.242 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 66.7 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 658 K (+385°C / +725°F) and receiving 44.83 S⊕ (~61,011 W/m²), Kepler-342 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-342 is classified as a stellar host with an effective photospheric temperature of 6,175 K, a radius of 1.472 R☉, a mass of 1.213 M☉, an estimated bolometric luminosity of 2.827 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.82 Gyr and a metallicity of [Fe/H] = -0.001 dex (near-solar heavy-element abundance). From Earth, Kepler-342 shines at apparent V-band magnitude 13.2 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-342 system is a multi-planet architecture hosting 4 confirmed worlds, with Kepler-342 d sharing its stellar neighborhood alongside Kepler-342 e, Kepler-342 b, Kepler-342 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-342 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,175 K |
| Stellar Radius | 1.4720 R☉ |
| Stellar Mass | 1.2130 M☉ |
| Bolometric Luminosity | 2.827 L☉ |
| Metallicity [Fe/H] | -0.001 dex |
| Stellar Age | 2.820 Gyr |
| Apparent Magnitude | V: 13.200 · G: 13.099 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.242000 AU |
| Orbital Period | 39.459 days |
| Mean Orbital Velocity | 66.7 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 84.5700° |
| Mean Bulk Density | 2.41 g/cm³ (18.4 km/s vesc) |
| Insolation Flux | 44.8280 S⊕ (~61,011 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2549.300 LY (781.611 pc) |