TOI-2109 b
TOI-2109 b is a hot Jupiter orbiting the F star TOI-2109 in the constellation Hercules. It lies about 855 light-years from Earth and was discovered in 2021 using the transit method.
How Big Is TOI-2109 b?
TOI-2109 b has a radius of 15.10 times that of Earth, or 1.35 times the radius of Jupiter. Its mass is 1,595 times that of Earth.
Is TOI-2109 b in the Habitable Zone?
TOI-2109 b orbits inside the inner edge of the habitable zone of TOI-2109. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-2109: 1.556–3.609 AU (conservative: 1.970–3.422 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-2109 b
The equilibrium temperature of TOI-2109 b is about 3,646 K (3,373 °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-2109 b — one full orbit around TOI-2109 — lasts just 16.1 hours, shorter than Mercury's 88-day year. It orbits at an average distance of 0.018 AU — closer to its star than Mercury is to the Sun.
How Was TOI-2109 b Discovered?
TOI-2109 b was discovered in 2021 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-2109 b?
TOI-2109 b is 854.7 light-years (262.0 parsecs) from Earth. Light arriving here tonight left the planet around the year 1172. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 15,042,720 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-2109 b scores 0.06, ranking #5,142 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-2109
TOI-2109
- Spectral type
- F
- Surface temperature
- 6,540 K (Sun: 5,772 K)
- Mass
- 1.45 M☉
- Radius
- 1.70 R☉
- Luminosity
- 4.7100 L☉
- Age
- 1.8 billion years (Sun: 4.6)
Planetary System
TOI-2109 b is the only planet known to orbit TOI-2109 so far.
TOI-2109 b — Complete Data
| Radius | 15.098 Earth radii (1.347 Jupiter radii) |
|---|---|
| Mass | 1,595.50 Earth masses (5.020 Jupiter masses) |
| Orbital period | 0.67 days |
| Orbital distance | 0.018 AU |
| Equilibrium temperature | 3,646 K (3,373 °C) |
| Earth Similarity Index | 0.06 |
| Distance from Earth | 854.7 light-years (262.0 parsecs) |
| Constellation | Hercules |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2021 |
Data: NASA Exoplanet Archive, last updated 2021-12-13. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-2109 b
Is TOI-2109 b habitable?
No — TOI-2109 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-2109 b?
TOI-2109 b is about 855 light-years from Earth in the constellation Hercules. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 15,042,720 years to get there.
How big is TOI-2109 b compared to Earth?
TOI-2109 b has 15.10 times the radius of Earth and about 1,595 times its mass.
How long is a year on TOI-2109 b?
One orbit around TOI-2109 takes 0.7 Earth days — short enough that 543 of its years would fit into one Earth year.
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