LTT 3780 b
Astrophysical Synthesis & Habitability Characterization
LTT 3780 b is a confirmed super-earth exoplanet orbiting the star LTT 3780, located approximately 71.7 light-years (21.98 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 0.1022% across the stellar disk), this world measures 1.325 Earth radii and has a measured mass of 2.46 Earth masses. Combining its mass and radius yields a mean bulk density of 5.83 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.4 g⊕ (13.73 m/s²), and an escape velocity of 15.2 km/s.
In its orbital architecture around LTT 3780, LTT 3780 b completes one full revolution every 0.768 Earth days at a semi-major axis of 0.01195 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 169.2 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 903 K (+630°C / +1166°F) and receiving 111.00 S⊕ (~151,071 W/m²), LTT 3780 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star LTT 3780 is classified as a low-mass red dwarf of spectral type M3.5 V with an effective photospheric temperature of 3,358 K, a radius of 0.38 R☉, a mass of 0.381 M☉, an estimated bolometric luminosity of 0.016 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.1 Gyr and a metallicity of [Fe/H] = 0.06 dex (metal-rich relative to the Sun). From Earth, LTT 3780 shines at apparent V-band magnitude 13.14 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The LTT 3780 system is a multi-planet architecture hosting 2 confirmed worlds, with LTT 3780 b sharing its stellar neighborhood alongside LTT 3780 c.
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 | LTT 3780 |
| Spectral Type | M3.5 V |
| Effective Temp (Teff) | 3,358 K |
| Stellar Radius | 0.3800 R☉ |
| Stellar Mass | 0.3810 M☉ |
| Bolometric Luminosity | 0.016 L☉ |
| Metallicity [Fe/H] | 0.060 dex |
| Stellar Age | 3.100 Gyr |
| Apparent Magnitude | V: 13.140 · G: 11.847 |
| System Architecture | 2 Stars, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.011950 AU |
| Orbital Period | 0.768 days |
| Mean Orbital Velocity | 169.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 86.1000° |
| Mean Bulk Density | 5.83 g/cm³ (15.2 km/s vesc) |
| Insolation Flux | 111.0000 S⊕ (~151,071 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 71.700 LY (21.981 pc) |