HS Psc b
Astrophysical Synthesis & Habitability Characterization
HS Psc b is a confirmed gas giant exoplanet orbiting the star HS Psc, located approximately 122.8 light-years (37.66 parsecs) from the Solar System. First announced in 2024 by McDonald Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.6 Earth radii (1.21 Jupiter radii) and has a measured mass of 464.029 Earth masses (1.46 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.02 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.51 g⊕ (24.61 m/s²), and an escape velocity of 65.3 km/s.
In its orbital architecture around HS Psc, HS Psc b completes one full revolution every 3.986 Earth days at a semi-major axis of 0.0435 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 118.7 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.27, swinging from 0.0318 AU at periapsis out to 0.0552 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 783 K (+510°C / +950°F) and receiving 64.47 S⊕ (~87,748 W/m²), HS Psc b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HS Psc is classified as an orange K-type star of spectral type K7 V with an effective photospheric temperature of 4,203 K, a radius of 0.65 R☉, a mass of 0.69 M☉, an estimated bolometric luminosity of 0.118 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.133 Gyr and a metallicity of [Fe/H] = -0.05 dex (near-solar heavy-element abundance). From Earth, HS Psc shines at apparent V-band magnitude 10.769 (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: McDonald Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HS Psc |
| Spectral Type | K7 V |
| Effective Temp (Teff) | 4,203 K |
| Stellar Radius | 0.6500 R☉ |
| Stellar Mass | 0.6900 M☉ |
| Bolometric Luminosity | 0.118 L☉ |
| Metallicity [Fe/H] | -0.050 dex |
| Stellar Age | 0.133 Gyr |
| Apparent Magnitude | V: 10.769 · G: 10.287 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.043500 AU |
| Orbital Period | 3.986 days |
| Mean Orbital Velocity | 118.7 km/s |
| Orbital Eccentricity (e) | 0.27000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.02 g/cm³ (65.3 km/s vesc) |
| Insolation Flux | 64.4735 S⊕ (~87,748 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 122.800 LY (37.660 pc) |