TOI-4860 b
Astrophysical Synthesis & Habitability Characterization
TOI-4860 b is a confirmed gas giant exoplanet orbiting the star TOI-4860, located approximately 261.4 light-years (80.14 parsecs) from the Solar System. First announced in 2023 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 4.9638% across the stellar disk), this world measures 8.7 Earth radii (0.78 Jupiter radii) and has a measured mass of 86.7 Earth masses (0.27 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.73 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.15 g⊕ (11.28 m/s²), and an escape velocity of 35.3 km/s.
In its orbital architecture around TOI-4860, TOI-4860 b completes one full revolution every 1.523 Earth days at a semi-major axis of 0.01808 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 129.2 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.008 (ranging from 0.0179 AU at periapsis to 0.0182 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 694 K (+421°C / +790°F) and receiving 42.50 S⊕ (~57,843 W/m²), TOI-4860 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-4860 is classified as a low-mass red dwarf of spectral type M3.5 V with an effective photospheric temperature of 3,260 K, a radius of 0.358 R☉, a mass of 0.34 M☉, an estimated bolometric luminosity of 0.013 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.5 Gyr and a metallicity of [Fe/H] = 0.27 dex (metal-rich relative to the Sun). From Earth, TOI-4860 shines at apparent V-band magnitude 16.47 (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-4860 |
| Spectral Type | M3.5 V |
| Effective Temp (Teff) | 3,260 K |
| Stellar Radius | 0.3580 R☉ |
| Stellar Mass | 0.3400 M☉ |
| Bolometric Luminosity | 0.013 L☉ |
| Metallicity [Fe/H] | 0.270 dex |
| Stellar Age | 4.500 Gyr |
| Apparent Magnitude | V: 16.470 · G: 15.109 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.018080 AU |
| Orbital Period | 1.523 days |
| Mean Orbital Velocity | 129.2 km/s |
| Orbital Eccentricity (e) | 0.00800 |
| Orbital Inclination (i) | 88.5000° |
| Mean Bulk Density | 0.73 g/cm³ (35.3 km/s vesc) |
| Insolation Flux | 42.5000 S⊕ (~57,843 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 261.400 LY (80.142 pc) |