HD 142 A d
Astrophysical Synthesis & Habitability Characterization
HD 142 A d is a confirmed gas giant exoplanet orbiting the star HD 142, located approximately 85.4 light-years (26.19 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 10.9 Earth radii (0.97 Jupiter radii) and has a measured mass of 82.635 Earth masses (0.26 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.35 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 30.8 km/s.
In its orbital architecture around HD 142, HD 142 A d completes one full revolution every 108.453 Earth days at a semi-major axis of 0.474 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 47.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.13 carries the world between 0.4124 AU at periapsis and 0.5356 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 530 K (+257°C / +495°F) and receiving 13.26 S⊕ (~18,050 W/m²), HD 142 A d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 142 is classified as a warm F-type star of spectral type F7V with an effective photospheric temperature of 6,245 K, a radius of 1.47 R☉, a mass of 1.21 M☉, an estimated bolometric luminosity of 2.949 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.12 Gyr and a metallicity of [Fe/H] = 0.09 dex (metal-rich relative to the Sun). From Earth, HD 142 shines at apparent V-band magnitude 5.7 (visible to the unaided human eye under dark skies) in the Southern celestial hemisphere. The HD 142 system is a multi-planet architecture hosting 3 confirmed worlds, with HD 142 A d sharing its stellar neighborhood alongside HD 142 b, HD 142 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 142 |
| Spectral Type | F7V |
| Effective Temp (Teff) | 6,245 K |
| Stellar Radius | 1.4700 R☉ |
| Stellar Mass | 1.2100 M☉ |
| Bolometric Luminosity | 2.949 L☉ |
| Metallicity [Fe/H] | 0.090 dex |
| Stellar Age | 3.120 Gyr |
| Apparent Magnitude | V: 5.700 · G: 5.584 |
| System Architecture | 2 Stars, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.474000 AU |
| Orbital Period | 108.453 days |
| Mean Orbital Velocity | 47.5 km/s |
| Orbital Eccentricity (e) | 0.13000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.35 g/cm³ (30.8 km/s vesc) |
| Insolation Flux | 13.2625 S⊕ (~18,050 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 85.400 LY (26.185 pc) |