K2-73 c
Astrophysical Synthesis & Habitability Characterization
K2-73 c is a confirmed gas giant exoplanet orbiting the star K2-73, located approximately 878 light-years (269.18 parsecs) from the Solar System. First announced in 2025 by W. M. Keck Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13 Earth radii (1.16 Jupiter radii) and has a measured mass of 1142 Earth masses (3.59 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.87 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 6.76 g⊕ (66.29 m/s²), and an escape velocity of 104.8 km/s.
In its orbital architecture around K2-73, K2-73 c completes one full revolution every 1000 Earth days (2.74Julian years).
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.000 R⊕, K2-73 c exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star K2-73 is classified as a stellar host with an effective photospheric temperature of 5,867 K, a radius of 1.058 R☉, a mass of 1.02 M☉, an estimated bolometric luminosity of 1.19 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.04 dex (near-solar heavy-element abundance). From Earth, K2-73 shines at apparent V-band magnitude 11.345 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The K2-73 system is a multi-planet architecture hosting 2 confirmed worlds, with K2-73 c sharing its stellar neighborhood alongside K2-73 b.
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: W. M. Keck Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | K2-73 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,867 K |
| Stellar Radius | 1.0580 R☉ |
| Stellar Mass | 1.0200 M☉ |
| Bolometric Luminosity | 1.19 L☉ |
| Metallicity [Fe/H] | 0.040 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 11.345 · G: 11.715 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 1000 days |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.87 g/cm³ (104.8 km/s vesc) |
| Insolation Flux | 0.2850 S⊕ (~388 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 878.000 LY (269.183 pc) |