CI Tau c
Astrophysical Synthesis & Habitability Characterization
CI Tau c is a confirmed gas giant exoplanet orbiting the star CI Tau, located approximately 515.3 light-years (158 parsecs) from the Solar System. First announced in 2024 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13 Earth radii (1.16 Jupiter radii) and has a measured mass of 1144.182 Earth masses (3.6 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.87 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 6.77 g⊕ (66.39 m/s²), and an escape velocity of 104.9 km/s.
In its orbital architecture around CI Tau, CI Tau c completes one full revolution every 25.2 Earth days at a semi-major axis of 0.17 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 73.4 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.58, swinging from 0.0714 AU at periapsis out to 0.2686 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 611 K (+338°C / +640°F) and receiving 19.25 S⊕ (~26,205 W/m²), CI Tau c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star CI Tau is classified as an orange K-type star of spectral type K7 with an effective photospheric temperature of 3,807 K, a radius of 1.8809 R☉, a mass of 0.9 M☉, an estimated bolometric luminosity of 0.667 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.003 Gyr. From Earth, CI Tau shines at apparent V-band magnitude 13.642 (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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | CI Tau |
| Spectral Type | K7 |
| Effective Temp (Teff) | 3,807 K |
| Stellar Radius | 1.8809 R☉ |
| Stellar Mass | 0.9000 M☉ |
| Bolometric Luminosity | 0.667 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | 0.003 Gyr |
| Apparent Magnitude | V: 13.642 · G: 12.145 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.170000 AU |
| Orbital Period | 25.2 days |
| Mean Orbital Velocity | 73.4 km/s |
| Orbital Eccentricity (e) | 0.58000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.87 g/cm³ (104.9 km/s vesc) |
| Insolation Flux | 19.2542 S⊕ (~26,205 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 515.300 LY (157.998 pc) |