TOI-674 b
Astrophysical Synthesis & Habitability Characterization
TOI-674 b is a confirmed sub-neptune exoplanet orbiting the star TOI-674, located approximately 150.3 light-years (46.09 parsecs) from the Solar System. First announced in 2021 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 1.3133% across the stellar disk), this world measures 5.25 Earth radii (0.47 Jupiter radii) and has a measured mass of 23.6 Earth masses. Combining its mass and radius yields a mean bulk density of 0.9 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.86 g⊕ (8.43 m/s²), and an escape velocity of 23.7 km/s.
In its orbital architecture around TOI-674, TOI-674 b completes one full revolution every 1.977 Earth days at a semi-major axis of 0.025 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 137.6 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 635 K (+362°C / +684°F) and receiving 38.40 S⊕ (~52,262 W/m²), TOI-674 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-674 is classified as a low-mass red dwarf of spectral type M2 V with an effective photospheric temperature of 3,514 K, a radius of 0.42 R☉, a mass of 0.42 M☉, an estimated bolometric luminosity of 0.024 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.17 dex (metal-rich relative to the Sun). From Earth, TOI-674 shines at apparent V-band magnitude 14.203 (faint and requiring research-grade or CCD telescopic photometry) 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-674 |
| Spectral Type | M2 V |
| Effective Temp (Teff) | 3,514 K |
| Stellar Radius | 0.4200 R☉ |
| Stellar Mass | 0.4200 M☉ |
| Bolometric Luminosity | 0.024 L☉ |
| Metallicity [Fe/H] | 0.170 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 14.203 · G: 13.091 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.025000 AU |
| Orbital Period | 1.977 days |
| Mean Orbital Velocity | 137.6 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.2100° |
| Mean Bulk Density | 0.9 g/cm³ (23.7 km/s vesc) |
| Insolation Flux | 38.4000 S⊕ (~52,262 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 150.300 LY (46.085 pc) |