HD 13908 b
Astrophysical Synthesis & Habitability Characterization
HD 13908 b is a confirmed gas giant exoplanet orbiting the star HD 13908, located approximately 259.5 light-years (79.55 parsecs) from the Solar System. First announced in 2013 by Haute-Provence Observatory 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 274.91 Earth masses (0.86 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.56 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.42 g⊕ (13.93 m/s²), and an escape velocity of 49.7 km/s.
In its orbital architecture around HD 13908, HD 13908 b completes one full revolution every 19.382 Earth days at a semi-major axis of 0.154 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 86.4 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.02 (ranging from 0.1509 AU at periapsis to 0.1571 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 993 K (+720°C / +1328°F) and receiving 168.64 S⊕ (~229,518 W/m²), HD 13908 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 13908 is classified as a warm F-type star of spectral type F8 V with an effective photospheric temperature of 6,255 K, a radius of 1.67 R☉, a mass of 1.29 M☉, an estimated bolometric luminosity of 3.83 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.9 Gyr and a metallicity of [Fe/H] = 0.01 dex (near-solar heavy-element abundance). From Earth, HD 13908 shines at apparent V-band magnitude 7.52 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The HD 13908 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 13908 b sharing its stellar neighborhood alongside HD 13908 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: Haute-Provence Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 13908 |
| Spectral Type | F8 V |
| Effective Temp (Teff) | 6,255 K |
| Stellar Radius | 1.6700 R☉ |
| Stellar Mass | 1.2900 M☉ |
| Bolometric Luminosity | 3.83 L☉ |
| Metallicity [Fe/H] | 0.010 dex |
| Stellar Age | 2.900 Gyr |
| Apparent Magnitude | V: 7.520 · G: 7.385 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.154000 AU |
| Orbital Period | 19.382 days |
| Mean Orbital Velocity | 86.4 km/s |
| Orbital Eccentricity (e) | 0.02000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.56 g/cm³ (49.7 km/s vesc) |
| Insolation Flux | 168.6392 S⊕ (~229,518 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 259.500 LY (79.552 pc) |