LHS 1815 b
Astrophysical Synthesis & Habitability Characterization
LHS 1815 b is a confirmed terrestrial exoplanet orbiting the star LHS 1815, located approximately 97.3 light-years (29.84 parsecs) from the Solar System. First announced in 2020 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.0396% across the stellar disk), this world measures 1.088 Earth radii and has a measured mass of 1.58 Earth masses. Combining its mass and radius yields a mean bulk density of 6.76 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 1.33 g⊕ (13.04 m/s²), and an escape velocity of 13.5 km/s.
In its orbital architecture around LHS 1815, LHS 1815 b completes one full revolution every 3.814 Earth days at a semi-major axis of 0.0404 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 115.2 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 617 K (+344°C / +651°F) and receiving 62.15 S⊕ (~84,585 W/m²), LHS 1815 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star LHS 1815 is classified as a low-mass red dwarf of spectral type M1 with an effective photospheric temperature of 3,643 K, a radius of 0.501 R☉, a mass of 0.502 M☉, an estimated bolometric luminosity of 0.04 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.12 dex (metal-poor relative to the Sun). From Earth, LHS 1815 shines at apparent V-band magnitude 12.167 (faint and requiring research-grade or CCD telescopic photometry) 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: Transiting Exoplanet Survey Satellite (TESS) · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | LHS 1815 |
| Spectral Type | M1 |
| Effective Temp (Teff) | 3,643 K |
| Stellar Radius | 0.5010 R☉ |
| Stellar Mass | 0.5020 M☉ |
| Bolometric Luminosity | 0.04 L☉ |
| Metallicity [Fe/H] | -0.120 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 12.167 · G: 11.236 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.040400 AU |
| Orbital Period | 3.814 days |
| Mean Orbital Velocity | 115.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.1250° |
| Mean Bulk Density | 6.76 g/cm³ (13.5 km/s vesc) |
| Insolation Flux | 62.1493 S⊕ (~84,585 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 97.300 LY (29.842 pc) |