TOI-700 c
Astrophysical Synthesis & Habitability Characterization
TOI-700 c is a confirmed sub-neptune exoplanet orbiting the star TOI-700, located approximately 101.5 light-years (31.13 parsecs) from the Solar System. First announced in 2020 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.3207% across the stellar disk), this world measures 2.535 Earth radii and has a measured mass of 6.96 Earth masses. Combining its mass and radius yields a mean bulk density of 2.36 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.08 g⊕ (10.59 m/s²), and an escape velocity of 18.5 km/s.
In its orbital architecture around TOI-700, TOI-700 c completes one full revolution every 16.051 Earth days at a semi-major axis of 0.0931 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 63.1 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.033 (ranging from 0.09 AU at periapsis to 0.0962 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 356 K (+83°C / +181°F) and receiving 2.64 S⊕ (~3,593 W/m²), TOI-700 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-700 is classified as a low-mass red dwarf of spectral type M2.5 V with an effective photospheric temperature of 3,459 K, a radius of 0.4104 R☉, a mass of 0.417 M☉, an estimated bolometric luminosity of 0.022 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.5 Gyr and a metallicity of [Fe/H] = -0.07 dex (near-solar heavy-element abundance). From Earth, TOI-700 shines at apparent V-band magnitude 13.151 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The TOI-700 system is a multi-planet architecture hosting 4 confirmed worlds, with TOI-700 c sharing its stellar neighborhood alongside TOI-700 b, TOI-700 e, TOI-700 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-700 |
| Spectral Type | M2.5 V |
| Effective Temp (Teff) | 3,459 K |
| Stellar Radius | 0.4104 R☉ |
| Stellar Mass | 0.4170 M☉ |
| Bolometric Luminosity | 0.022 L☉ |
| Metallicity [Fe/H] | -0.070 dex |
| Stellar Age | 1.500 Gyr |
| Apparent Magnitude | V: 13.151 · G: 12.067 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.093100 AU |
| Orbital Period | 16.051 days |
| Mean Orbital Velocity | 63.1 km/s |
| Orbital Eccentricity (e) | 0.03300 |
| Orbital Inclination (i) | 88.9420° |
| Mean Bulk Density | 2.36 g/cm³ (18.5 km/s vesc) |
| Insolation Flux | 2.6400 S⊕ (~3,593 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 101.500 LY (31.127 pc) |