HD 75898 c
Astrophysical Synthesis & Habitability Characterization
HD 75898 c is a confirmed gas giant exoplanet orbiting the star HD 75898, located approximately 254.6 light-years (78.05 parsecs) from the Solar System. First announced in 2024 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.6 Earth radii (1.12 Jupiter radii) and has a measured mass of 2698.363 Earth masses (8.49 Jupiter masses). Combining its mass and radius yields a mean bulk density of 7.44 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 17 g⊕ (166.71 m/s²), and an escape velocity of 163.7 km/s.
In its orbital architecture around HD 75898, HD 75898 c completes one full revolution every 6717 Earth days (18.39Julian years) at a semi-major axis of 7.39 AU (a wide outer-system orbit beyond Jupiter's 5.20 AU distance in our Solar System). Its mean orbital velocity is approximately 12 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.08 carries the world between 6.7988 AU at periapsis and 7.9812 AU at apoapsis, driving measurable seasonal insolation cycles.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 135 K (-138°C / -216°F) and an incident flux of 0.05 S⊕ (~72 W/m²), surface water and volatile species on HD 75898 c would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 75898 is classified as a warm F-type star of spectral type F8 V with an effective photospheric temperature of 6,122 K, a radius of 1.55 R☉, a mass of 1.295 M☉, an estimated bolometric luminosity of 3.028 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.2 Gyr and a metallicity of [Fe/H] = 0.29 dex (metal-rich relative to the Sun). From Earth, HD 75898 shines at apparent V-band magnitude 8.03 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The HD 75898 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 75898 c sharing its stellar neighborhood alongside HD 75898 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 | HD 75898 |
| Spectral Type | F8 V |
| Effective Temp (Teff) | 6,122 K |
| Stellar Radius | 1.5500 R☉ |
| Stellar Mass | 1.2950 M☉ |
| Bolometric Luminosity | 3.028 L☉ |
| Metallicity [Fe/H] | 0.290 dex |
| Stellar Age | 3.200 Gyr |
| Apparent Magnitude | V: 8.030 · G: 7.896 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 7.390000 AU |
| Orbital Period | 6717 days |
| Mean Orbital Velocity | 12 km/s |
| Orbital Eccentricity (e) | 0.08000 |
| Orbital Inclination (i) | 153.0000° |
| Mean Bulk Density | 7.44 g/cm³ (163.7 km/s vesc) |
| Insolation Flux | 0.0528 S⊕ (~72 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 254.600 LY (78.051 pc) |