TOI-4184 b
TOI-4184 b is a mini-Neptune orbiting the M5.5+/-0.5 star TOI-4184 in the constellation Hydrus. It lies about 226 light-years from Earth and was discovered in 2023 using the transit method.
How Big Is TOI-4184 b?
TOI-4184 b has a radius of 2.43 times that of Earth.
Is TOI-4184 b in the Habitable Zone?
TOI-4184 b orbits inside the inner edge of the habitable zone of TOI-4184. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-4184: 0.061–0.159 AU (conservative: 0.077–0.151 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-4184 b
The equilibrium temperature of TOI-4184 b is about 412 K (139 °C) — hotter than anywhere on Earth. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 4.80 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-4184 b — one full orbit around TOI-4184 — lasts 4.90 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.034 AU — closer to its star than Mercury is to the Sun.
How Was TOI-4184 b Discovered?
TOI-4184 b was discovered in 2023 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-4184 b?
TOI-4184 b is 226.2 light-years (69.4 parsecs) from Earth. Light arriving here tonight left the planet around the year 1800. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 3,981,120 years to make the journey.
Earth Similarity Index
The Earth Similarity Index (ESI) scores how physically similar a planet is to Earth, from 0 to 1, based on radius, density, escape velocity and surface temperature. TOI-4184 b scores 0.45, ranking #337 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-4184
TOI-4184
- Spectral type
- M5.5+/-0.5
- Surface temperature
- 3,238 K (Sun: 5,772 K)
- Mass
- 0.21 M☉
- Radius
- 0.23 R☉
- Luminosity
- 0.0054 L☉
- Age
- 6.7 billion years (Sun: 4.6)
Planetary System
TOI-4184 b is the only planet known to orbit TOI-4184 so far.
TOI-4184 b — Complete Data
| Radius | 2.430 Earth radii (0.217 Jupiter radii) |
|---|---|
| Orbital period | 4.90 days |
| Orbital distance | 0.034 AU |
| Equilibrium temperature | 412 K (139 °C) |
| Stellar irradiation | 4.80× Earth |
| Earth Similarity Index | 0.45 |
| Distance from Earth | 226.2 light-years (69.4 parsecs) |
| Constellation | Hydrus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2023-07-25. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-4184 b
Is TOI-4184 b habitable?
No — TOI-4184 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-4184 b?
TOI-4184 b is about 226 light-years from Earth in the constellation Hydrus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 3,981,120 years to get there.
How big is TOI-4184 b compared to Earth?
TOI-4184 b has 2.43 times the radius of Earth.
How long is a year on TOI-4184 b?
One orbit around TOI-4184 takes 4.9 Earth days — short enough that 75 of its years would fit into one Earth year.
Explore TOI-4184 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.
