TOI-1199 b
Astrophysical Synthesis & Habitability Characterization
TOI-1199 b is a confirmed gas giant exoplanet orbiting the star TOI-1199, located approximately 810.3 light-years (248.43 parsecs) from the Solar System. First announced in 2024 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.4419% across the stellar disk), this world measures 10.514 Earth radii (0.94 Jupiter radii) and has a measured mass of 75.961 Earth masses (0.24 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.36 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.69 g⊕ (6.77 m/s²), and an escape velocity of 30.1 km/s.
In its orbital architecture around TOI-1199, TOI-1199 b completes one full revolution every 3.671 Earth days at a semi-major axis of 0.04988 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 147.8 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.03 (ranging from 0.0484 AU at periapsis to 0.0514 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1486 K (+1213°C / +2215°F) and receiving 324.11 S⊕ (~441,119 W/m²), TOI-1199 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-1199 is classified as a stellar host with an effective photospheric temperature of 5,710 K, a radius of 1.45 R☉, a mass of 1.23 M☉, an estimated bolometric luminosity of 2.005 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.2 Gyr and a metallicity of [Fe/H] = 0.44 dex (metal-rich relative to the Sun). From Earth, TOI-1199 shines at apparent V-band magnitude 11.093 (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-1199 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,710 K |
| Stellar Radius | 1.4500 R☉ |
| Stellar Mass | 1.2300 M☉ |
| Bolometric Luminosity | 2.005 L☉ |
| Metallicity [Fe/H] | 0.440 dex |
| Stellar Age | 4.200 Gyr |
| Apparent Magnitude | V: 11.093 · G: 10.885 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.049880 AU |
| Orbital Period | 3.671 days |
| Mean Orbital Velocity | 147.8 km/s |
| Orbital Eccentricity (e) | 0.03000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.36 g/cm³ (30.1 km/s vesc) |
| Insolation Flux | 324.1140 S⊕ (~441,119 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 810.300 LY (248.427 pc) |