HD 103949 b
Astrophysical Synthesis & Habitability Characterization
HD 103949 b is a confirmed sub-neptune exoplanet orbiting the star HD 103949, located approximately 86.4 light-years (26.5 parsecs) from the Solar System. First announced in 2019 by Las Campanas Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 3.35 Earth radii (0.3 Jupiter radii) and has a measured mass of 11.2 Earth masses. Combining its mass and radius yields a mean bulk density of 1.64 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1 g⊕ (9.81 m/s²), and an escape velocity of 20.5 km/s.
In its orbital architecture around HD 103949, HD 103949 b completes one full revolution every 120.878 Earth days at a semi-major axis of 0.439 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 39.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.19 carries the world between 0.3556 AU at periapsis and 0.5224 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 3.350 R⊕, HD 103949 b exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star HD 103949 is classified as an orange K-type star of spectral type K3 V with an effective photospheric temperature of 4,792 K, a radius of 0.7531 R☉, a mass of 0.77 M☉, an estimated bolometric luminosity of 0.268 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.07 dex (near-solar heavy-element abundance). From Earth, HD 103949 shines at apparent V-band magnitude 8.7 (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: Las Campanas Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 103949 |
| Spectral Type | K3 V |
| Effective Temp (Teff) | 4,792 K |
| Stellar Radius | 0.7531 R☉ |
| Stellar Mass | 0.7700 M☉ |
| Bolometric Luminosity | 0.268 L☉ |
| Metallicity [Fe/H] | -0.070 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 8.700 · G: 8.385 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.439000 AU |
| Orbital Period | 120.878 days |
| Mean Orbital Velocity | 39.5 km/s |
| Orbital Eccentricity (e) | 0.19000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.64 g/cm³ (20.5 km/s vesc) |
| Insolation Flux | 1.3983 S⊕ (~1,903 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 86.400 LY (26.500 pc) |