TOI-1696 b
Astrophysical Synthesis & Habitability Characterization
TOI-1696 b is a confirmed sub-neptune exoplanet orbiting the star TOI-1696, located approximately 211.7 light-years (64.92 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 1.0422% across the stellar disk), this world measures 3.09 Earth radii (0.28 Jupiter radii) and has a measured mass of 48.8 Earth masses (0.15 Jupiter masses). Combining its mass and radius yields a mean bulk density of 9.12 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 5.11 g⊕ (50.11 m/s²), and an escape velocity of 44.5 km/s.
In its orbital architecture around TOI-1696, TOI-1696 b completes one full revolution every 2.5 Earth days at a semi-major axis of 0.0229 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 99.6 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 489 K (+216°C / +421°F) and receiving 13.50 S⊕ (~18,374 W/m²), TOI-1696 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-1696 is classified as a low-mass red dwarf of spectral type M5V with an effective photospheric temperature of 3,185 K, a radius of 0.2775 R☉, a mass of 0.255 M☉, an estimated bolometric luminosity of 0.00711 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.1 Gyr and a metallicity of [Fe/H] = 0.336 dex (metal-rich relative to the Sun). From Earth, TOI-1696 shines at apparent V-band magnitude 16.82 (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-1696 |
| Spectral Type | M5V |
| Effective Temp (Teff) | 3,185 K |
| Stellar Radius | 0.2775 R☉ |
| Stellar Mass | 0.2550 M☉ |
| Bolometric Luminosity | 0.00711 L☉ |
| Metallicity [Fe/H] | 0.336 dex |
| Stellar Age | 7.100 Gyr |
| Apparent Magnitude | V: 16.820 · G: 15.331 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.022900 AU |
| Orbital Period | 2.5 days |
| Mean Orbital Velocity | 99.6 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.4610° |
| Mean Bulk Density | 9.12 g/cm³ (44.5 km/s vesc) |
| Insolation Flux | 13.5000 S⊕ (~18,374 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 211.700 LY (64.917 pc) |