TOI-5916 b
Astrophysical Synthesis & Habitability Characterization
TOI-5916 b is a confirmed gas giant exoplanet orbiting the star TOI-5916, located approximately 651.4 light-years (199.72 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 4.9346% across the stellar disk), this world measures 11.8 Earth radii (1.05 Jupiter radii) and has a measured mass of 219 Earth masses (0.69 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.73 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.57 g⊕ (15.4 m/s²), and an escape velocity of 48.2 km/s.
In its orbital architecture around TOI-5916, TOI-5916 b completes one full revolution every 2.367 Earth days at a semi-major axis of 0.02789 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 128.2 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.045 (ranging from 0.0266 AU at periapsis to 0.0291 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 716 K (+443°C / +829°F) and receiving 43.80 S⊕ (~59,612 W/m²), TOI-5916 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-5916 is classified as a low-mass red dwarf of spectral type M2 with an effective photospheric temperature of 3,541 K, a radius of 0.487 R☉, a mass of 0.518 M☉, an estimated bolometric luminosity of 0.033 L☉. Stellar evolution modeling indicates an estimated stellar age of 5 Gyr and a metallicity of [Fe/H] = 0.04 dex (near-solar heavy-element abundance). From Earth, TOI-5916 shines at apparent V-band magnitude 16.602 (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-5916 |
| Spectral Type | M2 |
| Effective Temp (Teff) | 3,541 K |
| Stellar Radius | 0.4870 R☉ |
| Stellar Mass | 0.5180 M☉ |
| Bolometric Luminosity | 0.033 L☉ |
| Metallicity [Fe/H] | 0.040 dex |
| Stellar Age | 5.000 Gyr |
| Apparent Magnitude | V: 16.602 · G: 15.693 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.027890 AU |
| Orbital Period | 2.367 days |
| Mean Orbital Velocity | 128.2 km/s |
| Orbital Eccentricity (e) | 0.04500 |
| Orbital Inclination (i) | 89.1300° |
| Mean Bulk Density | 0.73 g/cm³ (48.2 km/s vesc) |
| Insolation Flux | 43.8000 S⊕ (~59,612 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 651.400 LY (199.724 pc) |