HD 10975 b
Astrophysical Synthesis & Habitability Characterization
HD 10975 b is a confirmed gas giant exoplanet orbiting the star HD 10975, located approximately 380 light-years (116.51 parsecs) from the Solar System. First announced in 2021 by Okayama Astrophysical Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 14.3 Earth radii (1.28 Jupiter radii) and has a measured mass of 143.023 Earth masses (0.45 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.27 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.7 g⊕ (6.86 m/s²), and an escape velocity of 35.4 km/s.
In its orbital architecture around HD 10975, HD 10975 b completes one full revolution every 283.8 Earth days at a semi-major axis of 0.95 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 36.4 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.442, swinging from 0.5301 AU at periapsis out to 1.3699 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 800 K (+527°C / +981°F) and receiving 68.30 S⊕ (~92,955 W/m²), HD 10975 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 10975 is classified as an orange K-type star of spectral type K0 III with an effective photospheric temperature of 4,840 K, a radius of 11.16 R☉, a mass of 1.41 M☉, an estimated bolometric luminosity of 61.32 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.21 dex (metal-poor relative to the Sun). From Earth, HD 10975 shines at apparent V-band magnitude 5.942 (visible to the unaided human eye under dark skies) 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: Okayama Astrophysical Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 10975 |
| Spectral Type | K0 III |
| Effective Temp (Teff) | 4,840 K |
| Stellar Radius | 11.1600 R☉ |
| Stellar Mass | 1.4100 M☉ |
| Bolometric Luminosity | 61.32 L☉ |
| Metallicity [Fe/H] | -0.210 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 5.942 · G: 5.671 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.950000 AU |
| Orbital Period | 283.8 days |
| Mean Orbital Velocity | 36.4 km/s |
| Orbital Eccentricity (e) | 0.44200 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.27 g/cm³ (35.4 km/s vesc) |
| Insolation Flux | 68.2992 S⊕ (~92,955 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 380.000 LY (116.506 pc) |