TOI-4201 b
TOI-4201 b is a hot Jupiter orbiting the M1.0+/-0.5 star TOI-4201 in the constellation Lepus. It lies about 617 light-years from Earth and was discovered in 2023 using the transit method.
How Big Is TOI-4201 b?
TOI-4201 b has a radius of 13.67 times that of Earth, or 1.22 times the radius of Jupiter. Its mass is 788 times that of Earth, giving it a density of 1.82 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is TOI-4201 b in the Habitable Zone?
TOI-4201 b orbits inside the inner edge of the habitable zone of TOI-4201. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-4201: 0.225–0.574 AU (conservative: 0.284–0.544 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-4201 b
The equilibrium temperature of TOI-4201 b is about 725 K (452 °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 45.20 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-4201 b — one full orbit around TOI-4201 — lasts 3.58 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.040 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.041).
How Was TOI-4201 b Discovered?
TOI-4201 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-4201 b?
TOI-4201 b is 616.5 light-years (189.0 parsecs) from Earth. Light arriving here tonight left the planet around the year 1410. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 10,850,400 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-4201 b scores 0.09, ranking #4,545 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-4201
TOI-4201
- Spectral type
- M1.0+/-0.5
- Surface temperature
- 3,794 K (Sun: 5,772 K)
- Mass
- 0.61 M☉
- Radius
- 0.63 R☉
- Luminosity
- 0.0760 L☉
- Age
- 1.4 billion years (Sun: 4.6)
Planetary System
TOI-4201 b is the only planet known to orbit TOI-4201 so far.
TOI-4201 b — Complete Data
| Radius | 13.675 Earth radii (1.220 Jupiter radii) |
|---|---|
| Mass | 788.21 Earth masses (2.480 Jupiter masses) |
| Density | 1.82 g/cm³ (Earth: 5.51) |
| Orbital period | 3.58 days |
| Orbital distance | 0.040 AU |
| Eccentricity | 0.041 |
| Equilibrium temperature | 725 K (452 °C) |
| Stellar irradiation | 45.20× Earth |
| Earth Similarity Index | 0.09 |
| Distance from Earth | 616.5 light-years (189.0 parsecs) |
| Constellation | Lepus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2023-09-19. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-4201 b
Is TOI-4201 b habitable?
No — TOI-4201 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-4201 b?
TOI-4201 b is about 617 light-years from Earth in the constellation Lepus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 10,850,400 years to get there.
How big is TOI-4201 b compared to Earth?
TOI-4201 b has 13.67 times the radius of Earth and about 788 times its mass.
How long is a year on TOI-4201 b?
One orbit around TOI-4201 takes 3.6 Earth days — short enough that 102 of its years would fit into one Earth year.
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