TOI-270 c
Astrophysical Synthesis & Habitability Characterization
TOI-270 c is a confirmed sub-neptune exoplanet orbiting the star TOI-270, located approximately 73.3 light-years (22.48 parsecs) from the Solar System. First announced in 2019 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.316% across the stellar disk), this world measures 2.33 Earth radii and has a measured mass of 6.2 Earth masses. Combining its mass and radius yields a mean bulk density of 2.7 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.14 g⊕ (11.18 m/s²), and an escape velocity of 18.2 km/s.
In its orbital architecture around TOI-270, TOI-270 c completes one full revolution every 5.661 Earth days at a semi-major axis of 0.04526 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 87 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.0044 (ranging from 0.0451 AU at periapsis to 0.0455 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 489 K (+216°C / +421°F) and receiving 47.06 S⊕ (~64,054 W/m²), TOI-270 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-270 is classified as a low-mass red dwarf of spectral type M with an effective photospheric temperature of 3,506 K, a radius of 0.38 R☉, a mass of 0.386 M☉, an estimated bolometric luminosity of 0.02 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.17 dex (metal-poor relative to the Sun). From Earth, TOI-270 shines at apparent V-band magnitude 12.603 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The TOI-270 system is a multi-planet architecture hosting 3 confirmed worlds, with TOI-270 c sharing its stellar neighborhood alongside TOI-270 b, TOI-270 d.
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-270 |
| Spectral Type | M |
| Effective Temp (Teff) | 3,506 K |
| Stellar Radius | 0.3800 R☉ |
| Stellar Mass | 0.3860 M☉ |
| Bolometric Luminosity | 0.02 L☉ |
| Metallicity [Fe/H] | -0.170 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 12.603 · G: 11.631 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.045260 AU |
| Orbital Period | 5.661 days |
| Mean Orbital Velocity | 87 km/s |
| Orbital Eccentricity (e) | 0.00440 |
| Orbital Inclination (i) | 89.3600° |
| Mean Bulk Density | 2.7 g/cm³ (18.2 km/s vesc) |
| Insolation Flux | 47.0639 S⊕ (~64,054 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 73.300 LY (22.479 pc) |