L 168-9 b
Astrophysical Synthesis & Habitability Characterization
L 168-9 b is a confirmed super-earth exoplanet orbiting the star L 168-9, located approximately 82 light-years (25.15 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 0.0612% across the stellar disk), this world measures 1.63 Earth radii and has a measured mass of 4.07 Earth masses. Combining its mass and radius yields a mean bulk density of 5.18 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.53 g⊕ (15 m/s²), and an escape velocity of 17.7 km/s.
In its orbital architecture around L 168-9, L 168-9 b completes one full revolution every 1.402 Earth days at a semi-major axis of 0.0208 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 161.5 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 998 K (+725°C / +1337°F) and receiving 149.37 S⊕ (~203,299 W/m²), L 168-9 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star L 168-9 is classified as a low-mass red dwarf of spectral type M0.5 V with an effective photospheric temperature of 3,842 K, a radius of 0.604 R☉, a mass of 0.614 M☉, an estimated bolometric luminosity of 0.071 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.03 dex (near-solar heavy-element abundance). From Earth, L 168-9 shines at apparent V-band magnitude 11.005 (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 | L 168-9 |
| Spectral Type | M0.5 V |
| Effective Temp (Teff) | 3,842 K |
| Stellar Radius | 0.6040 R☉ |
| Stellar Mass | 0.6140 M☉ |
| Bolometric Luminosity | 0.071 L☉ |
| Metallicity [Fe/H] | -0.030 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 11.005 · G: 10.232 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.020800 AU |
| Orbital Period | 1.402 days |
| Mean Orbital Velocity | 161.5 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 84.2700° |
| Mean Bulk Density | 5.18 g/cm³ (17.7 km/s vesc) |
| Insolation Flux | 149.3748 S⊕ (~203,299 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 82.000 LY (25.150 pc) |