TOI-2458 b
Astrophysical Synthesis & Habitability Characterization
TOI-2458 b is a confirmed sub-neptune exoplanet orbiting the star TOI-2458, located approximately 368.4 light-years (112.96 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 0.0392% across the stellar disk), this world measures 2.83 Earth radii and has a measured mass of 13.31 Earth masses. Combining its mass and radius yields a mean bulk density of 3.24 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.66 g⊕ (16.28 m/s²), and an escape velocity of 24.3 km/s.
In its orbital architecture around TOI-2458, TOI-2458 b completes one full revolution every 3.737 Earth days at a semi-major axis of 0.0482 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 140.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.087 carries the world between 0.044 AU at periapsis and 0.0524 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1509 K (+1236°C / +2257°F) and receiving 865.00 S⊕ (~1,177,265 W/m²), TOI-2458 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-2458 is classified as a warm F-type star of spectral type F9-F9.5 with an effective photospheric temperature of 6,005 K, a radius of 1.31 R☉, a mass of 1.05 M☉, an estimated bolometric luminosity of 2.002 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.7 Gyr and a metallicity of [Fe/H] = -0.1 dex (near-solar heavy-element abundance). From Earth, TOI-2458 shines at apparent V-band magnitude 9.202 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The TOI-2458 system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-2458 b sharing its stellar neighborhood alongside TOI-2458 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-2458 |
| Spectral Type | F9-F9.5 |
| Effective Temp (Teff) | 6,005 K |
| Stellar Radius | 1.3100 R☉ |
| Stellar Mass | 1.0500 M☉ |
| Bolometric Luminosity | 2.002 L☉ |
| Metallicity [Fe/H] | -0.100 dex |
| Stellar Age | 5.700 Gyr |
| Apparent Magnitude | V: 9.202 · G: 9.097 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.048200 AU |
| Orbital Period | 3.737 days |
| Mean Orbital Velocity | 140.3 km/s |
| Orbital Eccentricity (e) | 0.08700 |
| Orbital Inclination (i) | 84.0300° |
| Mean Bulk Density | 3.24 g/cm³ (24.3 km/s vesc) |
| Insolation Flux | 865.0000 S⊕ (~1,177,265 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 368.400 LY (112.958 pc) |