HD 134987 c
Astrophysical Synthesis & Habitability Characterization
HD 134987 c is a confirmed gas giant exoplanet orbiting the star HD 134987, located approximately 85.4 light-years (26.18 parsecs) from the Solar System. First announced in 2009 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.9 Earth radii (1.24 Jupiter radii) and has a measured mass of 260 Earth masses (0.82 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.53 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.35 g⊕ (13.24 m/s²), and an escape velocity of 48.4 km/s.
In its orbital architecture around HD 134987, HD 134987 c completes one full revolution every 5000 Earth days (13.69Julian years) at a semi-major axis of 5.8 AU (a wide outer-system orbit beyond Jupiter's 5.20 AU distance in our Solar System). Its mean orbital velocity is approximately 12.6 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.12 carries the world between 5.104 AU at periapsis and 6.496 AU at apoapsis, driving measurable seasonal insolation cycles.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 125 K (-148°C / -234°F) and an incident flux of 0.05 S⊕ (~73 W/m²), surface water and volatile species on HD 134987 c would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 134987 is classified as a solar-type yellow star of spectral type G5 V with an effective photospheric temperature of 5,585 K, a radius of 1.25 R☉, a mass of 1.1 M☉, an estimated bolometric luminosity of 1.364 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.4 Gyr and a metallicity of [Fe/H] = 0.28 dex (metal-rich relative to the Sun). From Earth, HD 134987 shines at apparent V-band magnitude 6.47 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 134987 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 134987 c sharing its stellar neighborhood alongside HD 134987 b.
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 134987 |
| Spectral Type | G5 V |
| Effective Temp (Teff) | 5,585 K |
| Stellar Radius | 1.2500 R☉ |
| Stellar Mass | 1.1000 M☉ |
| Bolometric Luminosity | 1.364 L☉ |
| Metallicity [Fe/H] | 0.280 dex |
| Stellar Age | 8.400 Gyr |
| Apparent Magnitude | V: 6.470 · G: 6.290 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 5.800000 AU |
| Orbital Period | 5000 days |
| Mean Orbital Velocity | 12.6 km/s |
| Orbital Eccentricity (e) | 0.12000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.53 g/cm³ (48.4 km/s vesc) |
| Insolation Flux | 0.0535 S⊕ (~73 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 85.400 LY (26.180 pc) |