HD 33142 d
Astrophysical Synthesis & Habitability Characterization
HD 33142 d is a confirmed gas giant exoplanet orbiting the star HD 33142, located approximately 395.9 light-years (121.38 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 9.32 Earth radii (0.83 Jupiter radii) and has a measured mass of 63.566 Earth masses (0.2 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.43 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.73 g⊕ (7.16 m/s²), and an escape velocity of 29.2 km/s.
In its orbital architecture around HD 33142, HD 33142 d completes one full revolution every 89.9 Earth days at a semi-major axis of 0.452 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 54.7 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.191 carries the world between 0.3657 AU at periapsis and 0.5383 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 736 K (+463°C / +865°F) and receiving 49.00 S⊕ (~66,683 W/m²), HD 33142 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 33142 is classified as an orange K-type star of spectral type K0 III with an effective photospheric temperature of 5,025 K, a radius of 4.17 R☉, a mass of 1.52 M☉, an estimated bolometric luminosity of 9.947 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.72 Gyr and a metallicity of [Fe/H] = 0.06 dex (metal-rich relative to the Sun). From Earth, HD 33142 shines at apparent V-band magnitude 7.96 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 33142 system is a multi-planet architecture hosting 3 confirmed worlds, with HD 33142 d sharing its stellar neighborhood alongside HD 33142 b, HD 33142 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 33142 |
| Spectral Type | K0 III |
| Effective Temp (Teff) | 5,025 K |
| Stellar Radius | 4.1700 R☉ |
| Stellar Mass | 1.5200 M☉ |
| Bolometric Luminosity | 9.947 L☉ |
| Metallicity [Fe/H] | 0.060 dex |
| Stellar Age | 2.720 Gyr |
| Apparent Magnitude | V: 7.960 · G: 7.713 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.452000 AU |
| Orbital Period | 89.9 days |
| Mean Orbital Velocity | 54.7 km/s |
| Orbital Eccentricity (e) | 0.19100 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.43 g/cm³ (29.2 km/s vesc) |
| Insolation Flux | 48.9956 S⊕ (~66,683 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 395.900 LY (121.375 pc) |