TOI-4311 b
TOI-4311 b is a lava world orbiting the K star TOI-4311 in the constellation Fornax. It lies about 440 light-years from Earth and was discovered in 2026 using the transit method.
How Big Is TOI-4311 b?
TOI-4311 b has a radius of 1.38 times that of Earth. Its mass is 4.5 times that of Earth, giving it a density of 9.30 g/cm³ — comparable to rocky planets like Earth (5.51 g/cm³).
Is TOI-4311 b in the Habitable Zone?
TOI-4311 b orbits inside the inner edge of the habitable zone of TOI-4311. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-4311: 0.507–1.223 AU (conservative: 0.643–1.160 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Temperature on TOI-4311 b
The equilibrium temperature of TOI-4311 b is about 1,664 K (1,391 °C) — hot enough to melt many metals. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 1,273 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-4311 b — one full orbit around TOI-4311 — lasts just 23.8 hours, shorter than Mercury's 88-day year. It orbits at an average distance of 0.018 AU — closer to its star than Mercury is to the Sun.
How Was TOI-4311 b Discovered?
TOI-4311 b was discovered in 2026 using the transit method, with observations from Transiting Exoplanet Survey Satellite (TESS).
The transit method watches a star for the tiny, regular dip in brightness that occurs when a planet crosses in front of it. The depth and timing of these dips reveal the planet's size and orbital period.
How Far Away Is TOI-4311 b?
TOI-4311 b is 440.3 light-years (135.0 parsecs) from Earth. Light arriving here tonight left the planet around the year 1586. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 7,749,280 years to make the journey.
The Host Star: TOI-4311
TOI-4311
- Spectral type
- K
- Surface temperature
- 5,063 K (Sun: 5,772 K)
- Mass
- 0.82 M☉
- Radius
- 0.84 R☉
- Luminosity
- 0.4220 L☉
- Age
- 6.6 billion years (Sun: 4.6)
The TOI-4311 Planetary System
TOI-4311 b is one of 2 known planets in the TOI-4311 system. Its siblings:
- TOI-4311 c (Super Earth)
TOI-4311 b — Complete Data
| Radius | 1.376 Earth radii (0.123 Jupiter radii) |
|---|---|
| Mass | 4.50 Earth masses (0.014 Jupiter masses) |
| Density | 9.30 g/cm³ (Earth: 5.51) |
| Orbital period | 0.99 days |
| Orbital distance | 0.018 AU |
| Equilibrium temperature | 1,664 K (1,391 °C) |
| Stellar irradiation | 1,273.00× Earth |
| Distance from Earth | 440.3 light-years (135.0 parsecs) |
| Constellation | Fornax |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2026 |
Data: NASA Exoplanet Archive, last updated 2026-05-21. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-4311 b
Is TOI-4311 b habitable?
No — TOI-4311 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-4311 b?
TOI-4311 b is about 440 light-years from Earth in the constellation Fornax. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 7,749,280 years to get there.
How big is TOI-4311 b compared to Earth?
TOI-4311 b has 1.38 times the radius of Earth and about 4.5 times its mass.
How long is a year on TOI-4311 b?
One orbit around TOI-4311 takes 1.0 Earth days — short enough that 369 of its years would fit into one Earth year.
Explore TOI-4311 b in the app
Browse, filter and compare 6,000+ exoplanets on iPhone, iPad and Apple Watch — with habitable-zone views, widgets and offline data.
