HD 81040 b
Astrophysical Synthesis & Habitability Characterization
HD 81040 b is a confirmed gas giant exoplanet orbiting the star HD 81040, located approximately 112.3 light-years (34.43 parsecs) from the Solar System. First announced in 2005 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.6 Earth radii (1.12 Jupiter radii) and has a measured mass of 2301.078 Earth masses (7.24 Jupiter masses). Combining its mass and radius yields a mean bulk density of 6.34 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 14.49 g⊕ (142.1 m/s²), and an escape velocity of 151.2 km/s.
In its orbital architecture around HD 81040, HD 81040 b completes one full revolution every 1002.7 Earth days (2.75Julian years) at a semi-major axis of 1.946 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 21.1 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.525, swinging from 0.9243 AU at periapsis out to 2.9677 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 12.600 R⊕, HD 81040 b 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 81040 is classified as a solar-type yellow star of spectral type G2/G3 with an effective photospheric temperature of 5,755 K, a radius of 0.91 R☉, a mass of 0.99 M☉, an estimated bolometric luminosity of 0.815 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.79 Gyr and a metallicity of [Fe/H] = -0.04 dex (near-solar heavy-element abundance). From Earth, HD 81040 shines at apparent V-band magnitude 7.72 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere.
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 81040 |
| Spectral Type | G2/G3 |
| Effective Temp (Teff) | 5,755 K |
| Stellar Radius | 0.9100 R☉ |
| Stellar Mass | 0.9900 M☉ |
| Bolometric Luminosity | 0.815 L☉ |
| Metallicity [Fe/H] | -0.040 dex |
| Stellar Age | 1.790 Gyr |
| Apparent Magnitude | V: 7.720 · G: 7.555 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.946000 AU |
| Orbital Period | 1002.7 days |
| Mean Orbital Velocity | 21.1 km/s |
| Orbital Eccentricity (e) | 0.52500 |
| Orbital Inclination (i) | 73.0000° |
| Mean Bulk Density | 6.34 g/cm³ (151.2 km/s vesc) |
| Insolation Flux | 0.2213 S⊕ (~301 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 112.300 LY (34.434 pc) |