TOI-1203 c
Astrophysical Synthesis & Habitability Characterization
TOI-1203 c is a confirmed sub-neptune exoplanet orbiting the star TOI-1203, located approximately 212 light-years (64.99 parsecs) from the Solar System. First announced in 2025 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.2 Earth radii and has a measured mass of 5.46 Earth masses. Combining its mass and radius yields a mean bulk density of 2.83 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.13 g⊕ (11.08 m/s²), and an escape velocity of 17.6 km/s.
In its orbital architecture around TOI-1203, TOI-1203 c completes one full revolution every 13.077 Earth days. Its moderate orbital eccentricity of e = 0.092 driving measurable seasonal insolation cycles.
ℹ️ Thermal & Atmospheric Regime: Current photometric and spectroscopic constraints for TOI-1203 c place it outside the conservative habitable zone definition pending further atmospheric characterization.
The host star TOI-1203 is classified as a solar-type yellow star of spectral type G3 V with an effective photospheric temperature of 5,737 K, a radius of 1.179 R☉, a mass of 0.886 M☉, an estimated bolometric luminosity of 1.351 L☉. Stellar evolution modeling indicates an estimated stellar age of 12.5 Gyr and a metallicity of [Fe/H] = -0.39 dex (metal-poor relative to the Sun). From Earth, TOI-1203 shines at apparent V-band magnitude 8.59 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The TOI-1203 system is a multi-planet architecture hosting 4 confirmed worlds, with TOI-1203 c sharing its stellar neighborhood alongside TOI-1203 b, TOI-1203.01, TOI-1203 e.
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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | TOI-1203 |
| Spectral Type | G3 V |
| Effective Temp (Teff) | 5,737 K |
| Stellar Radius | 1.1790 R☉ |
| Stellar Mass | 0.8860 M☉ |
| Bolometric Luminosity | 1.351 L☉ |
| Metallicity [Fe/H] | -0.390 dex |
| Stellar Age | 12.500 Gyr |
| Apparent Magnitude | V: 8.590 · G: 8.422 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 13.077 days |
| Orbital Eccentricity (e) | 0.09200 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.83 g/cm³ (17.6 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 212.000 LY (64.994 pc) |