TOI-2031 A b
TOI-2031 A b is a hot Jupiter orbiting TOI-2031 A in the constellation Cepheus. It lies about 901 light-years from Earth and was discovered in 2025 using the transit method.
How Big Is TOI-2031 A b?
TOI-2031 A b has a radius of 14.20 times that of Earth, or 1.27 times the radius of Jupiter. Its mass is 254 times that of Earth, giving it a density of 0.49 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is TOI-2031 A b in the Habitable Zone?
TOI-2031 A b orbits inside the inner edge of the habitable zone of TOI-2031 A. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-2031 A: 1.128–2.618 AU (conservative: 1.428–2.482 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-2031 A b
The equilibrium temperature of TOI-2031 A b is about 1,358 K (1,085 °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 567 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-2031 A b — one full orbit around TOI-2031 A — lasts 5.72 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.066 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.08).
How Was TOI-2031 A b Discovered?
TOI-2031 A b was discovered in 2025 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-2031 A b?
TOI-2031 A b is 900.5 light-years (276.1 parsecs) from Earth. Light arriving here tonight left the planet around the year 1126. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 15,848,800 years to make the journey.
The Host Star: TOI-2031 A
TOI-2031 A b belongs to a system of 2 stars; it orbits TOI-2031 A.
TOI-2031 A
- Surface temperature
- 6,490 K (Sun: 5,772 K)
- Mass
- 1.17 M☉
- Radius
- 1.24 R☉
- Luminosity
- 2.4600 L☉
- Age
- 2.0 billion years (Sun: 4.6)
Planetary System
TOI-2031 A b is the only planet known to orbit TOI-2031 A so far.
TOI-2031 A b — Complete Data
| Radius | 14.202 Earth radii (1.267 Jupiter radii) |
|---|---|
| Mass | 254.26 Earth masses (0.800 Jupiter masses) |
| Density | 0.49 g/cm³ (Earth: 5.51) |
| Orbital period | 5.72 days |
| Orbital distance | 0.066 AU |
| Eccentricity | 0.076 |
| Equilibrium temperature | 1,358 K (1,085 °C) |
| Stellar irradiation | 567.00× Earth |
| Distance from Earth | 900.5 light-years (276.1 parsecs) |
| Constellation | Cepheus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2025 |
Data: NASA Exoplanet Archive, last updated 2025-07-29. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-2031 A b
Is TOI-2031 A b habitable?
No — TOI-2031 A b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-2031 A b?
TOI-2031 A b is about 901 light-years from Earth in the constellation Cepheus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 15,848,800 years to get there.
How big is TOI-2031 A b compared to Earth?
TOI-2031 A b has 14.20 times the radius of Earth and about 254 times its mass.
How long is a year on TOI-2031 A b?
One orbit around TOI-2031 A takes 5.7 Earth days — short enough that 64 of its years would fit into one Earth year.
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