LHS 3154 b
Astrophysical Synthesis & Habitability Characterization
LHS 3154 b is a confirmed sub-neptune exoplanet orbiting the star LHS 3154, located approximately 51.4 light-years (15.76 parsecs) from the Solar System. First announced in 2023 by McDonald Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 3.69 Earth radii (0.33 Jupiter radii) and has a measured mass of 13.15 Earth masses. Combining its mass and radius yields a mean bulk density of 1.44 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.97 g⊕ (9.51 m/s²), and an escape velocity of 21.1 km/s.
In its orbital architecture around LHS 3154, LHS 3154 b completes one full revolution every 3.718 Earth days at a semi-major axis of 0.02262 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 66.2 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.076 carries the world between 0.0209 AU at periapsis and 0.0243 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 3.690 R⊕, LHS 3154 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 LHS 3154 is classified as a low-mass red dwarf of spectral type M6.5 with an effective photospheric temperature of 2,861 K, a radius of 0.1405 R☉, a mass of 0.1118 M☉, an estimated bolometric luminosity of 0.00119 L☉. Stellar evolution modeling indicates an estimated stellar age of 5 Gyr. From Earth, LHS 3154 shines at apparent V-band magnitude 17.65 (faint and requiring research-grade or CCD telescopic photometry) 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: McDonald Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | LHS 3154 |
| Spectral Type | M6.5 |
| Effective Temp (Teff) | 2,861 K |
| Stellar Radius | 0.1405 R☉ |
| Stellar Mass | 0.1118 M☉ |
| Bolometric Luminosity | 0.00119 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | 5.000 Gyr |
| Apparent Magnitude | V: 17.650 · G: 14.856 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.022620 AU |
| Orbital Period | 3.718 days |
| Mean Orbital Velocity | 66.2 km/s |
| Orbital Eccentricity (e) | 0.07600 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.44 g/cm³ (21.1 km/s vesc) |
| Insolation Flux | 3.7134 S⊕ (~5,054 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 51.400 LY (15.761 pc) |