TOI-1478 b
Astrophysical Synthesis & Habitability Characterization
TOI-1478 b is a confirmed gas giant exoplanet orbiting the star TOI-1478, located approximately 498.7 light-years (152.89 parsecs) from the Solar System. First announced in 2021 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 1.1009% across the stellar disk), this world measures 11.994 Earth radii (1.07 Jupiter radii) and has a measured mass of 279.689 Earth masses (0.88 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.89 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.94 g⊕ (19.02 m/s²), and an escape velocity of 54 km/s.
In its orbital architecture around TOI-1478, TOI-1478 b completes one full revolution every 10.18 Earth days at a semi-major axis of 0.0818 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 87.4 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.055 carries the world between 0.0773 AU at periapsis and 0.0863 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 918 K (+645°C / +1193°F) and receiving 261.01 S⊕ (~355,239 W/m²), TOI-1478 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-1478 is classified as a stellar host with an effective photospheric temperature of 5,597 K, a radius of 1.048 R☉, a mass of 0.947 M☉, an estimated bolometric luminosity of 0.967 L☉. Stellar evolution modeling indicates an estimated stellar age of 9.1 Gyr and a metallicity of [Fe/H] = 0.078 dex (metal-rich relative to the Sun). From Earth, TOI-1478 shines at apparent V-band magnitude 10.723 (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 | TOI-1478 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,597 K |
| Stellar Radius | 1.0480 R☉ |
| Stellar Mass | 0.9470 M☉ |
| Bolometric Luminosity | 0.967 L☉ |
| Metallicity [Fe/H] | 0.078 dex |
| Stellar Age | 9.100 Gyr |
| Apparent Magnitude | V: 10.723 · G: 10.662 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.081800 AU |
| Orbital Period | 10.18 days |
| Mean Orbital Velocity | 87.4 km/s |
| Orbital Eccentricity (e) | 0.05500 |
| Orbital Inclination (i) | 87.6300° |
| Mean Bulk Density | 0.89 g/cm³ (54 km/s vesc) |
| Insolation Flux | 261.0130 S⊕ (~355,239 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 498.700 LY (152.892 pc) |