HD 158038 b
Astrophysical Synthesis & Habitability Characterization
HD 158038 b is a confirmed gas giant exoplanet orbiting the star HD 158038, located approximately 309.4 light-years (94.86 parsecs) from the Solar System. First announced in 2011 by W. M. Keck Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.5 Earth radii (1.2 Jupiter radii) and has a measured mass of 486.28 Earth masses (1.53 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.09 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.67 g⊕ (26.18 m/s²), and an escape velocity of 67.1 km/s.
In its orbital architecture around HD 158038, HD 158038 b completes one full revolution every 521 Earth days (1.43Julian years) at a semi-major axis of 1.5 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 31.3 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.29, swinging from 1.065 AU at periapsis out to 1.935 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 406 K (+133°C / +271°F) and receiving 5.29 S⊕ (~7,198 W/m²), HD 158038 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 158038 is classified as an orange K-type star of spectral type K0 with an effective photospheric temperature of 4,860 K, a radius of 4.5 R☉, a mass of 1.3 M☉, an estimated bolometric luminosity of 10.136 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.5 Gyr and a metallicity of [Fe/H] = 0.19 dex (metal-rich relative to the Sun). From Earth, HD 158038 shines at apparent V-band magnitude 7.47 (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: W. M. Keck Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 158038 |
| Spectral Type | K0 |
| Effective Temp (Teff) | 4,860 K |
| Stellar Radius | 4.5000 R☉ |
| Stellar Mass | 1.3000 M☉ |
| Bolometric Luminosity | 10.136 L☉ |
| Metallicity [Fe/H] | 0.190 dex |
| Stellar Age | 2.500 Gyr |
| Apparent Magnitude | V: 7.470 · G: 7.207 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.500000 AU |
| Orbital Period | 521 days |
| Mean Orbital Velocity | 31.3 km/s |
| Orbital Eccentricity (e) | 0.29000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.09 g/cm³ (67.1 km/s vesc) |
| Insolation Flux | 5.2889 S⊕ (~7,198 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 309.400 LY (94.863 pc) |