TOI-5126 b
TOI-5126 b is a Neptune-like planet orbiting the F V star TOI-5126 in the constellation Leo. It lies about 523 light-years from Earth and was discovered in 2023 using the transit method.
How Big Is TOI-5126 b?
TOI-5126 b has a radius of 4.74 times that of Earth.
Is TOI-5126 b in the Habitable Zone?
TOI-5126 b orbits inside the inner edge of the habitable zone of TOI-5126. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-5126: 1.035–2.417 AU (conservative: 1.311–2.292 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-5126 b
The equilibrium temperature of TOI-5126 b is about 1,442 K (1,169 °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 467 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-5126 b — one full orbit around TOI-5126 — lasts 5.46 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.065 AU — closer to its star than Mercury is to the Sun.
How Was TOI-5126 b Discovered?
TOI-5126 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-5126 b?
TOI-5126 b is 523.2 light-years (160.4 parsecs) from Earth. Light arriving here tonight left the planet around the year 1503. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 9,208,320 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-5126 b scores 0.16, ranking #4,155 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-5126
TOI-5126
- Spectral type
- F V
- Surface temperature
- 6,150 K (Sun: 5,772 K)
- Mass
- 1.24 M☉
- Radius
- 1.24 R☉
- Luminosity
- 1.9900 L☉
- Age
- 0.8 billion years (Sun: 4.6)
The TOI-5126 Planetary System
TOI-5126 b is one of 2 known planets in the TOI-5126 system. Its siblings:
- TOI-5126 c (Sub Neptune)
TOI-5126 b — Complete Data
| Radius | 4.740 Earth radii (0.423 Jupiter radii) |
|---|---|
| Orbital period | 5.46 days |
| Orbital distance | 0.065 AU |
| Equilibrium temperature | 1,442 K (1,169 °C) |
| Stellar irradiation | 467.00× Earth |
| Earth Similarity Index | 0.16 |
| Distance from Earth | 523.2 light-years (160.4 parsecs) |
| Constellation | Leo |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2023-10-21. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-5126 b
Is TOI-5126 b habitable?
No — TOI-5126 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-5126 b?
TOI-5126 b is about 523 light-years from Earth in the constellation Leo. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 9,208,320 years to get there.
How big is TOI-5126 b compared to Earth?
TOI-5126 b has 4.74 times the radius of Earth.
How long is a year on TOI-5126 b?
One orbit around TOI-5126 takes 5.5 Earth days — short enough that 67 of its years would fit into one Earth year.
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