K2-253 b
Astrophysical Synthesis & Habitability Characterization
K2-253 b is a confirmed gas giant exoplanet orbiting the star K2-253, located approximately 2859 light-years (876.57 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 1.1151% across the stellar disk), this world has a measured radius of 12.67 Earth radii (1.13 R♃), though radial-velocity mass constraints remain unmeasured in the current composite catalogue.
In its orbital architecture around K2-253, K2-253 b completes one full revolution every 4.002 Earth days at a semi-major axis of 0.0506 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 137.6 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1238 K (+965°C / +1769°F) and receiving 365.82 S⊕ (~497,879 W/m²), K2-253 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-253 is classified as a stellar host with an effective photospheric temperature of 6,027 K, a radius of 1.1 R☉, a mass of 1.08 M☉, an estimated bolometric luminosity of 1.432 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, K2-253 shines at apparent V-band magnitude 15.002 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere.
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: K2 · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | K2-253 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,027 K |
| Stellar Radius | 1.1000 R☉ |
| Stellar Mass | 1.0800 M☉ |
| Bolometric Luminosity | 1.432 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 15.002 · G: 14.704 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.050600 AU |
| Orbital Period | 4.002 days |
| Mean Orbital Velocity | 137.6 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Insolation Flux | 365.8185 S⊕ (~497,879 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2859.000 LY (876.565 pc) |