TOI-4155 b
TOI-4155 b is a sub-Neptune orbiting TOI-4155 in the constellation Cepheus. It lies about 785 light-years from Earth and was discovered in 2025 using the transit method.
How Big Is TOI-4155 b?
TOI-4155 b has a radius of 3.21 times that of Earth.
Is TOI-4155 b in the Habitable Zone?
The position of TOI-4155 b relative to the habitable zone of TOI-4155 cannot be precisely determined from the available orbital data.
Habitable zone of TOI-4155: 0.702–1.656 AU (conservative: 0.889–1.570 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-4155 b
The equilibrium temperature of TOI-4155 b is about 1,255 K (982 °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.
Orbit and Year Length
A year on TOI-4155 b — one full orbit around TOI-4155 — lasts 3.32 Earth days, shorter than Mercury's 88-day year.
How Was TOI-4155 b Discovered?
TOI-4155 b was discovered in 2025 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-4155 b?
TOI-4155 b is 785.2 light-years (240.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1241. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 13,819,520 years to make the journey.
The Host Star: TOI-4155
TOI-4155
- Surface temperature
- 5,724 K (Sun: 5,772 K)
- Mass
- 1.16 M☉
- Radius
- 0.95 R☉
Planetary System
TOI-4155 b is the only planet known to orbit TOI-4155 so far.
TOI-4155 b — Complete Data
| Radius | 3.210 Earth radii (0.286 Jupiter radii) |
|---|---|
| Orbital period | 3.32 days |
| Equilibrium temperature | 1,255 K (982 °C) |
| Distance from Earth | 785.2 light-years (240.7 parsecs) |
| Constellation | Cepheus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2025 |
Data: NASA Exoplanet Archive, last updated 2025-08-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-4155 b
Is TOI-4155 b habitable?
TOI-4155 b is not known to orbit within the habitable zone of TOI-4155, and as a sub-Neptune it is an unlikely candidate for life as we know it.
How far away is TOI-4155 b?
TOI-4155 b is about 785 light-years from Earth in the constellation Cepheus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 13,819,520 years to get there.
How big is TOI-4155 b compared to Earth?
TOI-4155 b has 3.21 times the radius of Earth.
How long is a year on TOI-4155 b?
One orbit around TOI-4155 takes 3.3 Earth days — short enough that 110 of its years would fit into one Earth year.
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