HIP 107772 b
Astrophysical Synthesis & Habitability Characterization
HIP 107772 b is a confirmed sub-neptune exoplanet orbiting the star HIP 107772, located approximately 77.1 light-years (23.64 parsecs) from the Solar System. First announced in 2020 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 3.64 Earth radii (0.32 Jupiter radii) and has a measured mass of 12.9 Earth masses. Combining its mass and radius yields a mean bulk density of 1.47 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.97 g⊕ (9.51 m/s²), and an escape velocity of 21.1 km/s.
In its orbital architecture around HIP 107772, HIP 107772 b completes one full revolution every 55.199 Earth days at a semi-major axis of 0.243 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 47.9 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.18 carries the world between 0.1993 AU at periapsis and 0.2867 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 3.640 R⊕, HIP 107772 b 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 HIP 107772 is classified as a low-mass red dwarf of spectral type M0 V with an effective photospheric temperature of 4,006 K, a radius of 0.5139 R☉, a mass of 0.63 M☉, an estimated bolometric luminosity of 0.061 L☉. From Earth, HIP 107772 shines at apparent V-band magnitude 10.56 (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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HIP 107772 |
| Spectral Type | M0 V |
| Effective Temp (Teff) | 4,006 K |
| Stellar Radius | 0.5139 R☉ |
| Stellar Mass | 0.6300 M☉ |
| Bolometric Luminosity | 0.061 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | V: 10.560 · G: 9.932 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.243000 AU |
| Orbital Period | 55.199 days |
| Mean Orbital Velocity | 47.9 km/s |
| Orbital Eccentricity (e) | 0.18000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.47 g/cm³ (21.1 km/s vesc) |
| Insolation Flux | 1.1630 S⊕ (~1,583 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 77.100 LY (23.643 pc) |