TOI-4791 b
TOI-4791 b is a hot Jupiter orbiting TOI-4791 in the constellation Canis Major. It lies about 1,072 light-years from Earth and was discovered in 2023 using the transit method.
How Big Is TOI-4791 b?
TOI-4791 b has a radius of 12.44 times that of Earth, or 1.11 times the radius of Jupiter. Its mass is 734 times that of Earth, giving it a density of 2.09 g/cm³ — between that of rocky and gaseous planets.
Is TOI-4791 b in the Habitable Zone?
TOI-4791 b orbits inside the inner edge of the habitable zone of TOI-4791. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-4791: 1.143–2.675 AU (conservative: 1.448–2.536 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-4791 b
The equilibrium temperature of TOI-4791 b is about 1,472 K (1,199 °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 783 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-4791 b — one full orbit around TOI-4791 — lasts 4.28 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.056 AU — closer to its star than Mercury is to the Sun.
How Was TOI-4791 b Discovered?
TOI-4791 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-4791 b?
TOI-4791 b is 1,072.4 light-years (328.8 parsecs) from Earth. Light arriving here tonight left the planet about 1,072 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 18,874,240 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-4791 b scores 0.07, ranking #4,866 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-4791
TOI-4791
- Surface temperature
- 6,058 K (Sun: 5,772 K)
- Mass
- 1.24 M☉
- Radius
- 1.41 R☉
- Luminosity
- 2.4000 L☉
- Age
- 3.3 billion years (Sun: 4.6)
Planetary System
TOI-4791 b is the only planet known to orbit TOI-4791 so far.
TOI-4791 b — Complete Data
| Radius | 12.442 Earth radii (1.110 Jupiter radii) |
|---|---|
| Mass | 734.18 Earth masses (2.310 Jupiter masses) |
| Density | 2.09 g/cm³ (Earth: 5.51) |
| Orbital period | 4.28 days |
| Orbital distance | 0.056 AU |
| Equilibrium temperature | 1,472 K (1,199 °C) |
| Stellar irradiation | 783.20× Earth |
| Earth Similarity Index | 0.07 |
| Distance from Earth | 1,072.4 light-years (328.8 parsecs) |
| Constellation | Canis Major |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2023-02-27. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-4791 b
Is TOI-4791 b habitable?
No — TOI-4791 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-4791 b?
TOI-4791 b is about 1,072 light-years from Earth in the constellation Canis Major. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 18,874,240 years to get there.
How big is TOI-4791 b compared to Earth?
TOI-4791 b has 12.44 times the radius of Earth and about 734 times its mass.
How long is a year on TOI-4791 b?
One orbit around TOI-4791 takes 4.3 Earth days — short enough that 85 of its years would fit into one Earth year.
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