HIP 74890 b
Astrophysical Synthesis & Habitability Characterization
HIP 74890 b is a confirmed gas giant exoplanet orbiting the star HIP 74890, located approximately 256.5 light-years (78.66 parsecs) from the Solar System. First announced in 2016 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.3 Earth radii (1.19 Jupiter radii) and has a measured mass of 762.792 Earth masses (2.4 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.79 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 4.31 g⊕ (42.27 m/s²), and an escape velocity of 84.7 km/s.
In its orbital architecture around HIP 74890, HIP 74890 b completes one full revolution every 822.3 Earth days (2.25Julian years) at a semi-major axis of 2.1 AU (corresponding to the middle-system regime between Mars at 1.52 AU and Jupiter at 5.20 AU). Its mean orbital velocity is approximately 27.8 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.07 carries the world between 1.953 AU at periapsis and 2.247 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 388 K (+115°C / +239°F) and receiving 3.72 S⊕ (~5,061 W/m²), HIP 74890 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HIP 74890 is classified as an orange K-type star of spectral type K1 III with an effective photospheric temperature of 4,850 K, a radius of 5.77 R☉, a mass of 1.74 M☉, an estimated bolometric luminosity of 16.528 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.41 Gyr and a metallicity of [Fe/H] = 0.2 dex (metal-rich relative to the Sun). From Earth, HIP 74890 shines at apparent V-band magnitude 7.05 (accessible to binoculars and small amateur telescopes) 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 74890 |
| Spectral Type | K1 III |
| Effective Temp (Teff) | 4,850 K |
| Stellar Radius | 5.7700 R☉ |
| Stellar Mass | 1.7400 M☉ |
| Bolometric Luminosity | 16.528 L☉ |
| Metallicity [Fe/H] | 0.200 dex |
| Stellar Age | 4.410 Gyr |
| Apparent Magnitude | V: 7.050 · G: 6.752 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.100000 AU |
| Orbital Period | 822.3 days |
| Mean Orbital Velocity | 27.8 km/s |
| Orbital Eccentricity (e) | 0.07000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.79 g/cm³ (84.7 km/s vesc) |
| Insolation Flux | 3.7188 S⊕ (~5,061 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 256.500 LY (78.656 pc) |