Kepler-235 d
Astrophysical Synthesis & Habitability Characterization
Kepler-235 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-235, located approximately 1396 light-years (428.02 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1151% across the stellar disk), this world measures 2.05 Earth radii and has a measured mass of 4.86 Earth masses. Combining its mass and radius yields a mean bulk density of 3.11 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.16 g⊕ (11.38 m/s²), and an escape velocity of 17.2 km/s.
In its orbital architecture around Kepler-235, Kepler-235 d completes one full revolution every 20.061 Earth days at a semi-major axis of 0.122 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 66.2 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 401 K (+128°C / +262°F) and receiving 4.03 S⊕ (~5,485 W/m²), Kepler-235 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-235 is classified as a low-mass red dwarf of spectral type M0 V with an effective photospheric temperature of 4,255 K, a radius of 0.554 R☉, a mass of 0.581 M☉, an estimated bolometric luminosity of 0.09 L☉. Stellar evolution modeling indicates an estimated stellar age of 6 Gyr and a metallicity of [Fe/H] = -0.51 dex (metal-poor relative to the Sun). From Earth, Kepler-235 shines at apparent V-band magnitude 16.567 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-235 system is a multi-planet architecture hosting 4 confirmed worlds, with Kepler-235 d sharing its stellar neighborhood alongside Kepler-235 b, Kepler-235 c, Kepler-235 e.
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-235 |
| Spectral Type | M0 V |
| Effective Temp (Teff) | 4,255 K |
| Stellar Radius | 0.5540 R☉ |
| Stellar Mass | 0.5810 M☉ |
| Bolometric Luminosity | 0.09 L☉ |
| Metallicity [Fe/H] | -0.510 dex |
| Stellar Age | 6.000 Gyr |
| Apparent Magnitude | V: 16.567 · G: 15.970 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.122000 AU |
| Orbital Period | 20.061 days |
| Mean Orbital Velocity | 66.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.5760° |
| Mean Bulk Density | 3.11 g/cm³ (17.2 km/s vesc) |
| Insolation Flux | 4.0300 S⊕ (~5,485 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1396.000 LY (428.018 pc) |