HIP 107773 b
Astrophysical Synthesis & Habitability Characterization
HIP 107773 b is a confirmed gas giant exoplanet orbiting the star HIP 107773, located approximately 343.1 light-years (105.18 parsecs) from the Solar System. First announced in 2015 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.4 Earth radii (1.2 Jupiter radii) and has a measured mass of 629.303 Earth masses (1.98 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.44 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.5 g⊕ (34.32 m/s²), and an escape velocity of 76.7 km/s.
In its orbital architecture around HIP 107773, HIP 107773 b completes one full revolution every 144.3 Earth days at a semi-major axis of 0.72 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 54.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.09 carries the world between 0.6552 AU at periapsis and 0.7848 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 957 K (+684°C / +1263°F) and receiving 143.00 S⊕ (~194,623 W/m²), HIP 107773 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HIP 107773 is classified as an orange K-type star of spectral type K1 III with an effective photospheric temperature of 4,945 K, a radius of 11.6 R☉, a mass of 2.42 M☉, an estimated bolometric luminosity of 72.189 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.03 dex (near-solar heavy-element abundance). From Earth, HIP 107773 shines at apparent V-band magnitude 5.62 (visible to the unaided human eye under dark skies) 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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HIP 107773 |
| Spectral Type | K1 III |
| Effective Temp (Teff) | 4,945 K |
| Stellar Radius | 11.6000 R☉ |
| Stellar Mass | 2.4200 M☉ |
| Bolometric Luminosity | 72.189 L☉ |
| Metallicity [Fe/H] | 0.030 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 5.620 · G: 5.361 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.720000 AU |
| Orbital Period | 144.3 days |
| Mean Orbital Velocity | 54.3 km/s |
| Orbital Eccentricity (e) | 0.09000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.44 g/cm³ (76.7 km/s vesc) |
| Insolation Flux | 142.9997 S⊕ (~194,623 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 343.100 LY (105.180 pc) |