TOI-3540 A b
TOI-3540 A b is a hot Jupiter orbiting TOI-3540 A in the constellation Pegasus. It was discovered in 2022 using the transit method.
How Big Is TOI-3540 A b?
TOI-3540 A b has a radius of 23.54 times that of Earth, or 2.10 times the radius of Jupiter. Its mass is 375 times that of Earth, giving it a density of 0.07 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is TOI-3540 A b in the Habitable Zone?
TOI-3540 A b orbits inside the inner edge of the habitable zone of TOI-3540 A. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-3540 A: 0.932–2.194 AU (conservative: 1.181–2.081 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-3540 A b
The equilibrium temperature of TOI-3540 A b is about 1,498 K (1,225 °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 841 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-3540 A b — one full orbit around TOI-3540 A — lasts 3.12 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.043 AU — closer to its star than Mercury is to the Sun.
How Was TOI-3540 A b Discovered?
TOI-3540 A b was discovered in 2022 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.
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-3540 A b scores 0.04, ranking #5,322 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-3540 A
TOI-3540 A b belongs to a system of 2 stars; it orbits TOI-3540 A.
TOI-3540 A
- Surface temperature
- 5,810 K (Sun: 5,772 K)
- Mass
- 1.08 M☉
- Radius
- 1.23 R☉
- Luminosity
- 1.5490 L☉
- Age
- 6.0 billion years (Sun: 4.6)
Planetary System
TOI-3540 A b is the only planet known to orbit TOI-3540 A so far.
TOI-3540 A b — Complete Data
| Radius | 23.539 Earth radii (2.100 Jupiter radii) |
|---|---|
| Mass | 375.04 Earth masses (1.180 Jupiter masses) |
| Density | 0.07 g/cm³ (Earth: 5.51) |
| Orbital period | 3.12 days |
| Orbital distance | 0.043 AU |
| Equilibrium temperature | 1,498 K (1,225 °C) |
| Stellar irradiation | 841.30× Earth |
| Earth Similarity Index | 0.04 |
| Constellation | Pegasus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2022 |
Data: NASA Exoplanet Archive, last updated 2022-08-29. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-3540 A b
Is TOI-3540 A b habitable?
No — TOI-3540 A b orbits too close to its star and is too hot for liquid water to exist on its surface.
How big is TOI-3540 A b compared to Earth?
TOI-3540 A b has 23.54 times the radius of Earth and about 375 times its mass.
How long is a year on TOI-3540 A b?
One orbit around TOI-3540 A takes 3.1 Earth days — short enough that 117 of its years would fit into one Earth year.
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