HD 68988 b
Astrophysical Synthesis & Habitability Characterization
HD 68988 b is a confirmed gas giant exoplanet orbiting the star HD 68988, located approximately 198.4 light-years (60.85 parsecs) from the Solar System. First announced in 2001 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.4 Earth radii (1.2 Jupiter radii) and has a measured mass of 626.125 Earth masses (1.97 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.43 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.49 g⊕ (34.23 m/s²), and an escape velocity of 76.5 km/s.
In its orbital architecture around HD 68988, HD 68988 b completes one full revolution every 6.277 Earth days at a semi-major axis of 0.07 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 121.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.12 carries the world between 0.0616 AU at periapsis and 0.0784 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1179 K (+906°C / +1663°F) and receiving 340.13 S⊕ (~462,911 W/m²), HD 68988 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 68988 is classified as a solar-type yellow star of spectral type G2 V with an effective photospheric temperature of 5,932 K, a radius of 1.19 R☉, a mass of 1.28 M☉, an estimated bolometric luminosity of 1.573 L☉. Stellar evolution modeling indicates an estimated stellar age of 6 Gyr and a metallicity of [Fe/H] = 0.35 dex (metal-rich relative to the Sun). From Earth, HD 68988 shines at apparent V-band magnitude 8.2 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The HD 68988 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 68988 b sharing its stellar neighborhood alongside HD 68988 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 68988 |
| Spectral Type | G2 V |
| Effective Temp (Teff) | 5,932 K |
| Stellar Radius | 1.1900 R☉ |
| Stellar Mass | 1.2800 M☉ |
| Bolometric Luminosity | 1.573 L☉ |
| Metallicity [Fe/H] | 0.350 dex |
| Stellar Age | 6.000 Gyr |
| Apparent Magnitude | V: 8.200 · G: 8.046 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.070000 AU |
| Orbital Period | 6.277 days |
| Mean Orbital Velocity | 121.3 km/s |
| Orbital Eccentricity (e) | 0.12000 |
| Orbital Inclination (i) | 83.0000° |
| Mean Bulk Density | 1.43 g/cm³ (76.5 km/s vesc) |
| Insolation Flux | 340.1260 S⊕ (~462,911 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 198.400 LY (60.845 pc) |