K2-276 b
Astrophysical Synthesis & Habitability Characterization
K2-276 b is a confirmed sub-neptune exoplanet orbiting the star K2-276, located approximately 1592.1 light-years (488.15 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.1653% across the stellar disk), this world measures 3.77 Earth radii (0.34 Jupiter radii) and has a measured mass of 13.7 Earth masses. Combining its mass and radius yields a mean bulk density of 1.41 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.96 g⊕ (9.41 m/s²), and an escape velocity of 21.3 km/s.
In its orbital architecture around K2-276, K2-276 b completes one full revolution every 18.718 Earth days at a semi-major axis of 0.1291 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 75 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 583 K (+310°C / +590°F) and receiving 23.59 S⊕ (~32,109 W/m²), K2-276 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-276 is classified as a stellar host with an effective photospheric temperature of 5,139 K, a radius of 0.85 R☉, a mass of 0.82 M☉, an estimated bolometric luminosity of 0.452 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.07 dex (metal-rich relative to the Sun). From Earth, K2-276 shines at apparent V-band magnitude 14.654 (faint and requiring research-grade or CCD telescopic photometry) in the Northern 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 | K2-276 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,139 K |
| Stellar Radius | 0.8500 R☉ |
| Stellar Mass | 0.8200 M☉ |
| Bolometric Luminosity | 0.452 L☉ |
| Metallicity [Fe/H] | 0.070 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 14.654 · G: 14.379 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.129100 AU |
| Orbital Period | 18.718 days |
| Mean Orbital Velocity | 75 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.41 g/cm³ (21.3 km/s vesc) |
| Insolation Flux | 23.5921 S⊕ (~32,109 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1592.100 LY (488.152 pc) |