HD 69123 b
Astrophysical Synthesis & Habitability Characterization
HD 69123 b is a confirmed gas giant exoplanet orbiting the star HD 69123, located approximately 245 light-years (75.12 parsecs) from the Solar System. First announced in 2022 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.1 Earth radii (1.17 Jupiter radii) and has a measured mass of 982.09 Earth masses (3.09 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.41 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 5.72 g⊕ (56.09 m/s²), and an escape velocity of 96.9 km/s.
In its orbital architecture around HD 69123, HD 69123 b completes one full revolution every 1193.3 Earth days (3.27Julian years) at a semi-major axis of 2.482 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 22.6 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.19 carries the world between 2.0104 AU at periapsis and 2.9536 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 412 K (+139°C / +282°F) and receiving 4.79 S⊕ (~6,520 W/m²), HD 69123 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 69123 is classified as an orange K-type star of spectral type K1 III with an effective photospheric temperature of 4,842 K, a radius of 7.72 R☉, a mass of 1.68 M☉, an estimated bolometric luminosity of 29.392 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.05 dex (near-solar heavy-element abundance). From Earth, HD 69123 shines at apparent V-band magnitude 5.77 (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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 69123 |
| Spectral Type | K1 III |
| Effective Temp (Teff) | 4,842 K |
| Stellar Radius | 7.7200 R☉ |
| Stellar Mass | 1.6800 M☉ |
| Bolometric Luminosity | 29.392 L☉ |
| Metallicity [Fe/H] | 0.050 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 5.770 · G: 5.496 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.482000 AU |
| Orbital Period | 1193.3 days |
| Mean Orbital Velocity | 22.6 km/s |
| Orbital Eccentricity (e) | 0.19000 |
| Orbital Inclination (i) | 70.0000° |
| Mean Bulk Density | 2.41 g/cm³ (96.9 km/s vesc) |
| Insolation Flux | 4.7903 S⊕ (~6,520 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 245.000 LY (75.116 pc) |