TOI-1694 c
Astrophysical Synthesis & Habitability Characterization
TOI-1694 c is a confirmed gas giant exoplanet orbiting the star TOI-1694, located approximately 406.7 light-years (124.68 parsecs) from the Solar System. First announced in 2023 by W. M. Keck Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.8 Earth radii (1.23 Jupiter radii) and has a measured mass of 316.557 Earth masses (1 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.66 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.66 g⊕ (16.28 m/s²), and an escape velocity of 53.6 km/s.
In its orbital architecture around TOI-1694, TOI-1694 c completes one full revolution every 386.25 Earth days (1.06Julian years) at a semi-major axis of 0.974 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 27.4 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.111 carries the world between 0.8659 AU at periapsis and 1.0821 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.800 R⊕, TOI-1694 c exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star TOI-1694 is classified as an orange K-type star of spectral type K2 V - K3 V with an effective photospheric temperature of 5,005 K, a radius of 0.812 R☉, a mass of 0.828 M☉, an estimated bolometric luminosity of 0.371 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.8 Gyr and a metallicity of [Fe/H] = 0.04 dex (near-solar heavy-element abundance). From Earth, TOI-1694 shines at apparent V-band magnitude 11.446 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The TOI-1694 system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-1694 c sharing its stellar neighborhood alongside TOI-1694 b.
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: W. M. Keck Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | TOI-1694 |
| Spectral Type | K2 V - K3 V |
| Effective Temp (Teff) | 5,005 K |
| Stellar Radius | 0.8120 R☉ |
| Stellar Mass | 0.8280 M☉ |
| Bolometric Luminosity | 0.371 L☉ |
| Metallicity [Fe/H] | 0.040 dex |
| Stellar Age | 7.800 Gyr |
| Apparent Magnitude | V: 11.446 · G: 11.310 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.974000 AU |
| Orbital Period | 386.25 days |
| Mean Orbital Velocity | 27.4 km/s |
| Orbital Eccentricity (e) | 0.11100 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.66 g/cm³ (53.6 km/s vesc) |
| Insolation Flux | 0.4016 S⊕ (~547 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 406.700 LY (124.680 pc) |