K2-61 b
Astrophysical Synthesis & Habitability Characterization
K2-61 b is a confirmed super-earth exoplanet orbiting the star K2-61, located approximately 1323.3 light-years (405.73 parsecs) from the Solar System. First announced in 2016 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0313% across the stellar disk), this world measures 1.92 Earth radii and has a measured mass of 4.35 Earth masses. Combining its mass and radius yields a mean bulk density of 3.39 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.18 g⊕ (11.57 m/s²), and an escape velocity of 16.8 km/s.
In its orbital architecture around K2-61, K2-61 b completes one full revolution every 2.573 Earth days at a semi-major axis of 0.0392 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 165.7 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1325 K (+1052°C / +1926°F) and receiving 730.00 S⊕ (~993,530 W/m²), K2-61 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-61 is classified as a stellar host with an effective photospheric temperature of 5,748 K, a radius of 0.995 R☉, a mass of 0.97 M☉, an estimated bolometric luminosity of 0.97 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.03 dex (near-solar heavy-element abundance). From Earth, K2-61 shines at apparent V-band magnitude 13.173 (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 | K2-61 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,748 K |
| Stellar Radius | 0.9950 R☉ |
| Stellar Mass | 0.9700 M☉ |
| Bolometric Luminosity | 0.97 L☉ |
| Metallicity [Fe/H] | 0.030 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 13.173 · G: 12.858 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.039200 AU |
| Orbital Period | 2.573 days |
| Mean Orbital Velocity | 165.7 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 85.9963° |
| Mean Bulk Density | 3.39 g/cm³ (16.8 km/s vesc) |
| Insolation Flux | 730.0000 S⊕ (~993,530 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1323.300 LY (405.732 pc) |