TOI-4588 b

Astrophysical Synthesis & Habitability Characterization

TOI-4588 b is a confirmed sub-neptune exoplanet orbiting the star TOI-4588, located approximately 734.4 light-years (225.18 parsecs) from the Solar System. First announced in 2026 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0291% across the stellar disk), this world measures 2.929 Earth radii and has a measured mass of 8.9 Earth masses. Combining its mass and radius yields a mean bulk density of 1.95 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.04 g⊕ (10.2 m/s²), and an escape velocity of 19.5 km/s.

In its orbital architecture around TOI-4588, TOI-4588 b completes one full revolution every 13.119 Earth days at a semi-major axis of 0.1376 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 114.1 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 1768 K (+1495°C / +2723°F) and receiving 2,310.43 S⊕ (~3,144,495 W/m²), TOI-4588 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star TOI-4588 is classified as a stellar host with an effective photospheric temperature of 7,746 K, a radius of 1.5746 R☉, a mass of 2.018 M☉, an estimated bolometric luminosity of 8.008 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.86 Gyr and a metallicity of [Fe/H] = 0.21 dex (metal-rich relative to the Sun). From Earth, TOI-4588 shines at apparent V-band magnitude 9.24 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere.

Discovery Facility: Kepler · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).