HD 96700 d
Astrophysical Synthesis & Habitability Characterization
HD 96700 d is a confirmed sub-neptune exoplanet orbiting the star HD 96700, located approximately 82.9 light-years (25.41 parsecs) from the Solar System. First announced in 2021 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 3.61 Earth radii (0.32 Jupiter radii) and has a measured mass of 12.7 Earth masses. Combining its mass and radius yields a mean bulk density of 1.49 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.97 g⊕ (9.51 m/s²), and an escape velocity of 21 km/s.
In its orbital architecture around HD 96700, HD 96700 d completes one full revolution every 103.5 Earth days at a semi-major axis of 0.424 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 44.6 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.27, swinging from 0.3095 AU at periapsis out to 0.5385 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 466 K (+193°C / +379°F) and receiving 7.68 S⊕ (~10,447 W/m²), HD 96700 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 96700 is classified as a solar-type yellow star of spectral type G0 V with an effective photospheric temperature of 5,845 K, a radius of 1.16 R☉, a mass of 0.89 M☉, an estimated bolometric luminosity of 1.409 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.6 Gyr and a metallicity of [Fe/H] = -0.18 dex (metal-poor relative to the Sun). From Earth, HD 96700 shines at apparent V-band magnitude 6.51 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 96700 system is a multi-planet architecture hosting 3 confirmed worlds, with HD 96700 d sharing its stellar neighborhood alongside HD 96700 b, HD 96700 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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 96700 |
| Spectral Type | G0 V |
| Effective Temp (Teff) | 5,845 K |
| Stellar Radius | 1.1600 R☉ |
| Stellar Mass | 0.8900 M☉ |
| Bolometric Luminosity | 1.409 L☉ |
| Metallicity [Fe/H] | -0.180 dex |
| Stellar Age | 8.600 Gyr |
| Apparent Magnitude | V: 6.510 · G: 6.355 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.424000 AU |
| Orbital Period | 103.5 days |
| Mean Orbital Velocity | 44.6 km/s |
| Orbital Eccentricity (e) | 0.27000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.49 g/cm³ (21 km/s vesc) |
| Insolation Flux | 7.6762 S⊕ (~10,447 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 82.900 LY (25.411 pc) |