HAT-P-2 c
Astrophysical Synthesis & Habitability Characterization
HAT-P-2 c is a confirmed gas giant exoplanet orbiting the star HAT-P-2, located approximately 416.7 light-years (127.77 parsecs) from the Solar System. First announced in 2023 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.4 Earth radii (1.11 Jupiter radii) and has a measured mass of 3400.764 Earth masses (10.7 Jupiter masses). Combining its mass and radius yields a mean bulk density of 9.84 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 22.12 g⊕ (216.92 m/s²), and an escape velocity of 185.2 km/s.
In its orbital architecture around HAT-P-2, HAT-P-2 c completes one full revolution every 8500 Earth days (23.27Julian years). The planet follows a highly eccentric trajectory (e = 0.37), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 12.400 R⊕, HAT-P-2 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 HAT-P-2 is classified as a warm F-type star of spectral type F8 with an effective photospheric temperature of 6,412 K, a radius of 1.416 R☉, a mass of 1.33 M☉, an estimated bolometric luminosity of 3.041 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.44 Gyr and a metallicity of [Fe/H] = 0.12 dex (metal-rich relative to the Sun). From Earth, HAT-P-2 shines at apparent V-band magnitude 8.72 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The HAT-P-2 system is a multi-planet architecture hosting 2 confirmed worlds, with HAT-P-2 c sharing its stellar neighborhood alongside HAT-P-2 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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HAT-P-2 |
| Spectral Type | F8 |
| Effective Temp (Teff) | 6,412 K |
| Stellar Radius | 1.4160 R☉ |
| Stellar Mass | 1.3300 M☉ |
| Bolometric Luminosity | 3.041 L☉ |
| Metallicity [Fe/H] | 0.120 dex |
| Stellar Age | 1.440 Gyr |
| Apparent Magnitude | V: 8.720 · G: 8.598 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 8500 days |
| Orbital Eccentricity (e) | 0.37000 |
| Orbital Inclination (i) | 90.0000° |
| Mean Bulk Density | 9.84 g/cm³ (185.2 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 416.700 LY (127.774 pc) |