HD 103774 b
Astrophysical Synthesis & Habitability Characterization
HD 103774 b is a confirmed gas giant exoplanet orbiting the star HD 103774, located approximately 184 light-years (56.41 parsecs) from the Solar System. First announced in 2013 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.3 Earth radii (1.19 Jupiter radii) and has a measured mass of 116 Earth masses (0.36 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.27 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.66 g⊕ (6.47 m/s²), and an escape velocity of 33 km/s.
In its orbital architecture around HD 103774, HD 103774 b completes one full revolution every 5.888 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 129.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.09 carries the world between 0.0637 AU at periapsis and 0.0763 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1487 K (+1214°C / +2217°F) and receiving 714.17 S⊕ (~971,991 W/m²), HD 103774 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 103774 is classified as a warm F-type star of spectral type F5 V with an effective photospheric temperature of 6,489 K, a radius of 1.581 R☉, a mass of 1.335 M☉, an estimated bolometric luminosity of 3.976 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.05 Gyr and a metallicity of [Fe/H] = 0.28 dex (metal-rich relative to the Sun). From Earth, HD 103774 shines at apparent V-band magnitude 7.135 (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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 103774 |
| Spectral Type | F5 V |
| Effective Temp (Teff) | 6,489 K |
| Stellar Radius | 1.5810 R☉ |
| Stellar Mass | 1.3350 M☉ |
| Bolometric Luminosity | 3.976 L☉ |
| Metallicity [Fe/H] | 0.280 dex |
| Stellar Age | 1.050 Gyr |
| Apparent Magnitude | V: 7.135 · G: 7.009 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.070000 AU |
| Orbital Period | 5.888 days |
| Mean Orbital Velocity | 129.3 km/s |
| Orbital Eccentricity (e) | 0.09000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.27 g/cm³ (33 km/s vesc) |
| Insolation Flux | 714.1738 S⊕ (~971,991 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 184.000 LY (56.409 pc) |