TOI-1238 b
Astrophysical Synthesis & Habitability Characterization
TOI-1238 b is a confirmed terrestrial exoplanet orbiting the star TOI-1238, located approximately 230.6 light-years (70.72 parsecs) from the Solar System. First announced in 2022 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.0366% across the stellar disk), this world measures 1.21 Earth radii and has a measured mass of 3.76 Earth masses. Combining its mass and radius yields a mean bulk density of 11.7 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 2.57 g⊕ (25.2 m/s²), and an escape velocity of 19.7 km/s.
In its orbital architecture around TOI-1238, TOI-1238 b completes one full revolution every 0.765 Earth days at a semi-major axis of 0.0139 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 197.8 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.25, swinging from 0.0104 AU at periapsis out to 0.0174 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1133 K (+860°C / +1580°F) and receiving 442.00 S⊕ (~601,562 W/m²), TOI-1238 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-1238 is classified as an orange K-type star of spectral type K7/M0 with an effective photospheric temperature of 4,089 K, a radius of 0.58 R☉, a mass of 0.59 M☉, an estimated bolometric luminosity of 0.084 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.8 Gyr and a metallicity of [Fe/H] = 0.31 dex (metal-rich relative to the Sun). From Earth, TOI-1238 shines at apparent V-band magnitude 12.796 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The TOI-1238 system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-1238 b sharing its stellar neighborhood alongside TOI-1238 c.
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-1238 |
| Spectral Type | K7/M0 |
| Effective Temp (Teff) | 4,089 K |
| Stellar Radius | 0.5800 R☉ |
| Stellar Mass | 0.5900 M☉ |
| Bolometric Luminosity | 0.084 L☉ |
| Metallicity [Fe/H] | 0.310 dex |
| Stellar Age | 0.800 Gyr |
| Apparent Magnitude | V: 12.796 · G: 12.222 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.013900 AU |
| Orbital Period | 0.765 days |
| Mean Orbital Velocity | 197.8 km/s |
| Orbital Eccentricity (e) | 0.25000 |
| Orbital Inclination (i) | 86.5100° |
| Mean Bulk Density | 11.7 g/cm³ (19.7 km/s vesc) |
| Insolation Flux | 442.0000 S⊕ (~601,562 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 230.600 LY (70.715 pc) |