HD 141399 d
Astrophysical Synthesis & Habitability Characterization
HD 141399 d is a confirmed gas giant exoplanet orbiting the star HD 141399, located approximately 120.7 light-years (37.02 parsecs) from the Solar System. First announced in 2014 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.7 Earth radii (1.22 Jupiter radii) and has a measured mass of 375.039 Earth masses (1.18 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.8 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2 g⊕ (19.61 m/s²), and an escape velocity of 58.5 km/s.
In its orbital architecture around HD 141399, HD 141399 d completes one full revolution every 1069.8 Earth days (2.93Julian years) at a semi-major axis of 2.09 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 21.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.074 carries the world between 1.9353 AU at periapsis and 2.2447 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.700 R⊕, HD 141399 d exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star HD 141399 is classified as an orange K-type star of spectral type K0 with an effective photospheric temperature of 5,600 K, a radius of 1.3872 R☉, a mass of 1.07 M☉, an estimated bolometric luminosity of 1.698 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.35 dex (metal-rich relative to the Sun). From Earth, HD 141399 shines at apparent V-band magnitude 7.209 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The HD 141399 system is a multi-planet architecture hosting 4 confirmed worlds, with HD 141399 d sharing its stellar neighborhood alongside HD 141399 b, HD 141399 c, HD 141399 e.
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 141399 |
| Spectral Type | K0 |
| Effective Temp (Teff) | 5,600 K |
| Stellar Radius | 1.3872 R☉ |
| Stellar Mass | 1.0700 M☉ |
| Bolometric Luminosity | 1.698 L☉ |
| Metallicity [Fe/H] | 0.350 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 7.209 · G: 7.009 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.090000 AU |
| Orbital Period | 1069.8 days |
| Mean Orbital Velocity | 21.3 km/s |
| Orbital Eccentricity (e) | 0.07400 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.8 g/cm³ (58.5 km/s vesc) |
| Insolation Flux | 0.3640 S⊕ (~495 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 120.700 LY (37.017 pc) |