TOI-756 c
Astrophysical Synthesis & Habitability Characterization
TOI-756 c is a confirmed gas giant exoplanet orbiting the star TOI-756, located approximately 281.1 light-years (86.18 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 13 Earth radii (1.16 Jupiter radii) and has a measured mass of 1287.205 Earth masses (4.05 Jupiter masses). Combining its mass and radius yields a mean bulk density of 3.23 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 7.62 g⊕ (74.73 m/s²), and an escape velocity of 111.3 km/s.
In its orbital architecture around TOI-756, TOI-756 c completes one full revolution every 149.4 Earth days at a semi-major axis of 0.439 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 32 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.445, swinging from 0.2436 AU at periapsis out to 0.6344 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.000 R⊕, TOI-756 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-756 is classified as a low-mass red dwarf of spectral type M1 V with an effective photospheric temperature of 3,657 K, a radius of 0.505 R☉, a mass of 0.505 M☉, an estimated bolometric luminosity of 0.041 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.2 Gyr and a metallicity of [Fe/H] = 0.196 dex (metal-rich relative to the Sun). From Earth, TOI-756 shines at apparent V-band magnitude 14.607 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The TOI-756 system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-756 c sharing its stellar neighborhood alongside TOI-756 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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | TOI-756 |
| Spectral Type | M1 V |
| Effective Temp (Teff) | 3,657 K |
| Stellar Radius | 0.5050 R☉ |
| Stellar Mass | 0.5050 M☉ |
| Bolometric Luminosity | 0.041 L☉ |
| Metallicity [Fe/H] | 0.196 dex |
| Stellar Age | 3.200 Gyr |
| Apparent Magnitude | V: 14.607 · G: 13.696 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.439000 AU |
| Orbital Period | 149.4 days |
| Mean Orbital Velocity | 32 km/s |
| Orbital Eccentricity (e) | 0.44500 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 3.23 g/cm³ (111.3 km/s vesc) |
| Insolation Flux | 0.2400 S⊕ (~327 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 281.100 LY (86.176 pc) |