TOI-1820 b
Astrophysical Synthesis & Habitability Characterization
TOI-1820 b is a confirmed gas giant exoplanet orbiting the star TOI-1820, located approximately 810.5 light-years (248.5 parsecs) from the Solar System. First announced in 2022 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.6019% across the stellar disk), this world measures 12.778 Earth radii (1.14 Jupiter radii) and has a measured mass of 731.005 Earth masses (2.3 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.93 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 4.48 g⊕ (43.93 m/s²), and an escape velocity of 84.6 km/s.
In its orbital architecture around TOI-1820, TOI-1820 b completes one full revolution every 4.861 Earth days at a semi-major axis of 0.061 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 136.5 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.043 (ranging from 0.0584 AU at periapsis to 0.0636 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1375 K (+1102°C / +2016°F) and receiving 292.25 S⊕ (~397,745 W/m²), TOI-1820 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-1820 is classified as a stellar host with an effective photospheric temperature of 5,734 K, a radius of 1.51 R☉, a mass of 1.04 M☉, an estimated bolometric luminosity of 2.211 L☉. Stellar evolution modeling indicates an estimated stellar age of 11 Gyr and a metallicity of [Fe/H] = 0.14 dex (metal-rich relative to the Sun). From Earth, TOI-1820 shines at apparent V-band magnitude 10.899 (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: Transiting Exoplanet Survey Satellite (TESS) · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | TOI-1820 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,734 K |
| Stellar Radius | 1.5100 R☉ |
| Stellar Mass | 1.0400 M☉ |
| Bolometric Luminosity | 2.211 L☉ |
| Metallicity [Fe/H] | 0.140 dex |
| Stellar Age | 11.000 Gyr |
| Apparent Magnitude | V: 10.899 · G: 10.965 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.061000 AU |
| Orbital Period | 4.861 days |
| Mean Orbital Velocity | 136.5 km/s |
| Orbital Eccentricity (e) | 0.04300 |
| Orbital Inclination (i) | 84.4000° |
| Mean Bulk Density | 1.93 g/cm³ (84.6 km/s vesc) |
| Insolation Flux | 292.2450 S⊕ (~397,745 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 810.500 LY (248.504 pc) |