HD 109988 b
Astrophysical Synthesis & Habitability Characterization
HD 109988 b is a confirmed gas giant exoplanet orbiting the star HD 109988, located approximately 138.7 light-years (42.53 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 12.1 Earth radii (1.08 Jupiter radii) and has a measured mass of 6935.334 Earth masses (21.82 Jupiter masses). Combining its mass and radius yields a mean bulk density of 21.59 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 47.37 g⊕ (464.54 m/s²), and an escape velocity of 267.8 km/s.
In its orbital architecture around HD 109988, HD 109988 b completes one full revolution every 17132.159 Earth days (46.91Julian years) at a semi-major axis of 12.518 AU (a wide outer-system orbit beyond Jupiter's 5.20 AU distance in our Solar System). Its mean orbital velocity is approximately 7.9 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.056 carries the world between 11.817 AU at periapsis and 13.219 AU at apoapsis, driving measurable seasonal insolation cycles.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 66 K (-207°C / -341°F) and an incident flux of 0.00 S⊕ (~4 W/m²), surface water and volatile species on HD 109988 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 109988 is classified as a stellar host with an effective photospheric temperature of 5,186 K, a radius of 0.8697 R☉, a mass of 0.88 M☉, an estimated bolometric luminosity of 0.491 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.14 dex (metal-rich relative to the Sun). From Earth, HD 109988 shines at apparent V-band magnitude 8.9 (accessible to binoculars and small amateur telescopes) in the Southern 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 109988 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,186 K |
| Stellar Radius | 0.8697 R☉ |
| Stellar Mass | 0.8800 M☉ |
| Bolometric Luminosity | 0.491 L☉ |
| Metallicity [Fe/H] | 0.140 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 8.900 · G: 8.661 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 12.518000 AU |
| Orbital Period | 17132.159 days |
| Mean Orbital Velocity | 7.9 km/s |
| Orbital Eccentricity (e) | 0.05600 |
| Orbital Inclination (i) | 33.9920° |
| Mean Bulk Density | 21.59 g/cm³ (267.8 km/s vesc) |
| Insolation Flux | 0.0031 S⊕ (~4 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 138.700 LY (42.528 pc) |