K2-290 b
Astrophysical Synthesis & Habitability Characterization
K2-290 b is a confirmed sub-neptune exoplanet orbiting the star K2-290, located approximately 890.1 light-years (272.91 parsecs) from the Solar System. First announced in 2019 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0345% across the stellar disk), this world measures 3.06 Earth radii (0.27 Jupiter radii) and has a measured mass of 10.9 Earth masses. Combining its mass and radius yields a mean bulk density of 2.1 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 21.1 km/s.
In its orbital architecture around K2-290, K2-290 b completes one full revolution every 9.212 Earth days at a semi-major axis of 0.0923 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 109 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 1230 K (+957°C / +1755°F) and receiving 308.99 S⊕ (~420,542 W/m²), K2-290 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-290 is classified as a stellar host with an effective photospheric temperature of 6,302 K, a radius of 1.511 R☉, a mass of 1.194 M☉, an estimated bolometric luminosity of 3.231 L☉. Stellar evolution modeling indicates an estimated stellar age of 4 Gyr and a metallicity of [Fe/H] = -0.06 dex (near-solar heavy-element abundance). From Earth, K2-290 shines at apparent V-band magnitude 11.114 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The K2-290 system is a multi-planet architecture hosting 2 confirmed worlds, with K2-290 b sharing its stellar neighborhood alongside K2-290 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: K2 · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | K2-290 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,302 K |
| Stellar Radius | 1.5110 R☉ |
| Stellar Mass | 1.1940 M☉ |
| Bolometric Luminosity | 3.231 L☉ |
| Metallicity [Fe/H] | -0.060 dex |
| Stellar Age | 4.000 Gyr |
| Apparent Magnitude | V: 11.114 · G: 10.820 |
| System Architecture | 3 Stars, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.092300 AU |
| Orbital Period | 9.212 days |
| Mean Orbital Velocity | 109 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.1400° |
| Mean Bulk Density | 2.1 g/cm³ (21.1 km/s vesc) |
| Insolation Flux | 308.9946 S⊕ (~420,542 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 890.100 LY (272.909 pc) |