TOI-3278 b
Astrophysical Synthesis & Habitability Characterization
TOI-3278 b is a confirmed gas giant exoplanet orbiting the star TOI-3278, located approximately 2950.9 light-years (904.75 parsecs) from the Solar System. First announced in 2026 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.8404% across the stellar disk), this world measures 13.899 Earth radii (1.24 Jupiter radii) and has a measured mass of 95.349 Earth masses (0.3 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.2 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.49 g⊕ (4.81 m/s²), and an escape velocity of 29.3 km/s.
In its orbital architecture around TOI-3278, TOI-3278 b completes one full revolution every 3.246 Earth days at a semi-major axis of 0.043 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 144.1 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 1561 K (+1288°C / +2350°F) and receiving 1,030.00 S⊕ (~1,401,830 W/m²), TOI-3278 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-3278 is classified as a solar-type yellow star of spectral type G2-G4 V with an effective photospheric temperature of 5,720 K, a radius of 1.39 R☉, a mass of 1.04 M☉, an estimated bolometric luminosity of 1.856 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.9 Gyr and a metallicity of [Fe/H] = 0.04 dex (near-solar heavy-element abundance). From Earth, TOI-3278 shines at apparent V-band magnitude 14.161 (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-3278 |
| Spectral Type | G2-G4 V |
| Effective Temp (Teff) | 5,720 K |
| Stellar Radius | 1.3900 R☉ |
| Stellar Mass | 1.0400 M☉ |
| Bolometric Luminosity | 1.856 L☉ |
| Metallicity [Fe/H] | 0.040 dex |
| Stellar Age | 8.900 Gyr |
| Apparent Magnitude | V: 14.161 · G: 13.996 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.043000 AU |
| Orbital Period | 3.246 days |
| Mean Orbital Velocity | 144.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 83.0000° |
| Mean Bulk Density | 0.2 g/cm³ (29.3 km/s vesc) |
| Insolation Flux | 1030.0000 S⊕ (~1,401,830 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2950.900 LY (904.752 pc) |