HD 12235 b
Astrophysical Synthesis & Habitability Characterization
HD 12235 b is a confirmed sub-neptune exoplanet orbiting the star HD 12235, located approximately 103.6 light-years (31.76 parsecs) from the Solar System. First announced in 2022 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 3.23 Earth radii (0.29 Jupiter radii) and has a measured mass of 10.488 Earth masses. Combining its mass and radius yields a mean bulk density of 1.72 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.01 g⊕ (9.9 m/s²), and an escape velocity of 20.2 km/s.
In its orbital architecture around HD 12235, HD 12235 b completes one full revolution every 4.363 Earth days at a semi-major axis of 0.054 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 134.6 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.376, swinging from 0.0337 AU at periapsis out to 0.0743 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1667 K (+1394°C / +2541°F) and receiving 1,287.93 S⊕ (~1,752,869 W/m²), HD 12235 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 12235 is classified as a stellar host with an effective photospheric temperature of 5,986 K, a radius of 1.8019 R☉, a mass of 1.1 M☉, an estimated bolometric luminosity of 3.74 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.31 dex (metal-rich relative to the Sun). From Earth, HD 12235 shines at apparent V-band magnitude 5.881 (visible to the unaided human eye under dark skies) in the Northern celestial hemisphere. The HD 12235 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 12235 b sharing its stellar neighborhood alongside HD 12235 c.
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 12235 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,986 K |
| Stellar Radius | 1.8019 R☉ |
| Stellar Mass | 1.1000 M☉ |
| Bolometric Luminosity | 3.74 L☉ |
| Metallicity [Fe/H] | 0.310 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 5.881 · G: 5.741 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.054000 AU |
| Orbital Period | 4.363 days |
| Mean Orbital Velocity | 134.6 km/s |
| Orbital Eccentricity (e) | 0.37600 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.72 g/cm³ (20.2 km/s vesc) |
| Insolation Flux | 1287.9273 S⊕ (~1,752,869 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 103.600 LY (31.763 pc) |