TOI-2458 c
Astrophysical Synthesis & Habitability Characterization
TOI-2458 c 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 La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 3.18 Earth radii (0.28 Jupiter radii) and has a measured mass of 10.22 Earth masses. Combining its mass and radius yields a mean bulk density of 1.75 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.01 g⊕ (9.9 m/s²), and an escape velocity of 20.1 km/s.
In its orbital architecture around TOI-2458, TOI-2458 c completes one full revolution every 16.553 Earth days at a semi-major axis of 0.129 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 84.8 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.29, swinging from 0.0916 AU at periapsis out to 0.1664 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 923 K (+650°C / +1202°F) and receiving 131.86 S⊕ (~179,455 W/m²), TOI-2458 c 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 c sharing its stellar neighborhood alongside TOI-2458 b.
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: La Silla Observatory · 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) | 0.129000 AU |
| Orbital Period | 16.553 days |
| Mean Orbital Velocity | 84.8 km/s |
| Orbital Eccentricity (e) | 0.29000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.75 g/cm³ (20.1 km/s vesc) |
| Insolation Flux | 131.8551 S⊕ (~179,455 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 368.400 LY (112.958 pc) |