TOI-757 b
Astrophysical Synthesis & Habitability Characterization
TOI-757 b is a confirmed sub-neptune exoplanet orbiting the star TOI-757, located approximately 196.8 light-years (60.34 parsecs) from the Solar System. First announced in 2024 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.0863% across the stellar disk), this world measures 2.5 Earth radii and has a measured mass of 10.5 Earth masses. Combining its mass and radius yields a mean bulk density of 3.71 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.68 g⊕ (16.48 m/s²), and an escape velocity of 22.9 km/s.
In its orbital architecture around TOI-757, TOI-757 b completes one full revolution every 17.468 Earth days at a semi-major axis of 0.122 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 76 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.39, swinging from 0.0744 AU at periapsis out to 0.1696 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 641 K (+368°C / +694°F) and receiving 24.36 S⊕ (~33,160 W/m²), TOI-757 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-757 is classified as an orange K-type star of spectral type K0 V with an effective photospheric temperature of 5,278 K, a radius of 0.78 R☉, a mass of 0.8 M☉, an estimated bolometric luminosity of 0.424 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.5 Gyr and a metallicity of [Fe/H] = -0.27 dex (metal-poor relative to the Sun). From Earth, TOI-757 shines at apparent V-band magnitude 9.743 (accessible to binoculars and small amateur telescopes) in the Southern 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-757 |
| Spectral Type | K0 V |
| Effective Temp (Teff) | 5,278 K |
| Stellar Radius | 0.7800 R☉ |
| Stellar Mass | 0.8000 M☉ |
| Bolometric Luminosity | 0.424 L☉ |
| Metallicity [Fe/H] | -0.270 dex |
| Stellar Age | 7.500 Gyr |
| Apparent Magnitude | V: 9.743 · G: 9.554 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.122000 AU |
| Orbital Period | 17.468 days |
| Mean Orbital Velocity | 76 km/s |
| Orbital Eccentricity (e) | 0.39000 |
| Orbital Inclination (i) | 89.5000° |
| Mean Bulk Density | 3.71 g/cm³ (22.9 km/s vesc) |
| Insolation Flux | 24.3644 S⊕ (~33,160 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 196.800 LY (60.342 pc) |