TOI-3261 b
TOI-3261 b is a super-Earth orbiting the K1.5+/-1 star TOI-3261 in the constellation Hydrus. It lies about 979 light-years from Earth and was discovered in 2024 using the transit method.
How Big Is TOI-3261 b?
TOI-3261 b has a radius of 3.82 times that of Earth. Its mass is 30.3 times that of Earth, giving it a density of 3.00 g/cm³ — between that of rocky and gaseous planets.
Is TOI-3261 b in the Habitable Zone?
TOI-3261 b orbits inside the inner edge of the habitable zone of TOI-3261. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-3261: 0.512–1.234 AU (conservative: 0.648–1.170 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-3261 b
The equilibrium temperature of TOI-3261 b is about 1,722 K (1,449 °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 1,466 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-3261 b — one full orbit around TOI-3261 — lasts just 21.2 hours, shorter than Mercury's 88-day year. It orbits at an average distance of 0.017 AU — closer to its star than Mercury is to the Sun.
How Was TOI-3261 b Discovered?
TOI-3261 b was discovered in 2024 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-3261 b?
TOI-3261 b is 978.9 light-years (300.1 parsecs) from Earth. Light arriving here tonight left the planet around the year 1048. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 17,228,640 years to make the journey.
The Host Star: TOI-3261
TOI-3261
- Spectral type
- K1.5+/-1
- Surface temperature
- 5,068 K (Sun: 5,772 K)
- Mass
- 0.86 M☉
- Radius
- 0.85 R☉
- Luminosity
- 0.4300 L☉
- Age
- 6.5 billion years (Sun: 4.6)
Planetary System
TOI-3261 b is the only planet known to orbit TOI-3261 so far.
TOI-3261 b — Complete Data
| Radius | 3.820 Earth radii (0.341 Jupiter radii) |
|---|---|
| Mass | 30.30 Earth masses (0.095 Jupiter masses) |
| Density | 3.00 g/cm³ (Earth: 5.51) |
| Orbital period | 0.88 days |
| Orbital distance | 0.017 AU |
| Equilibrium temperature | 1,722 K (1,449 °C) |
| Stellar irradiation | 1,466.00× Earth |
| Distance from Earth | 978.9 light-years (300.1 parsecs) |
| Constellation | Hydrus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2024 |
Data: NASA Exoplanet Archive, last updated 2024-07-22. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-3261 b
Is TOI-3261 b habitable?
No — TOI-3261 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-3261 b?
TOI-3261 b is about 979 light-years from Earth in the constellation Hydrus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 17,228,640 years to get there.
How big is TOI-3261 b compared to Earth?
TOI-3261 b has 3.82 times the radius of Earth and about 30.3 times its mass.
How long is a year on TOI-3261 b?
One orbit around TOI-3261 takes 0.9 Earth days — short enough that 414 of its years would fit into one Earth year.
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