TOI-4145 A b
TOI-4145 A b is a hot Jupiter orbiting TOI-4145 A in the constellation Cepheus. It lies about 670 light-years from Earth and was discovered in 2023 using the transit method.
How Big Is TOI-4145 A b?
TOI-4145 A b has a radius of 13.31 times that of Earth, or 1.19 times the radius of Jupiter. Its mass is 137 times that of Earth, giving it a density of 0.32 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is TOI-4145 A b in the Habitable Zone?
TOI-4145 A b orbits inside the inner edge of the habitable zone of TOI-4145 A. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-4145 A: 0.555–1.327 AU (conservative: 0.703–1.258 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Temperature on TOI-4145 A b
The equilibrium temperature of TOI-4145 A b is about 1,074 K (801 °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 223 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-4145 A b — one full orbit around TOI-4145 A — lasts 4.07 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.048 AU — closer to its star than Mercury is to the Sun.
How Was TOI-4145 A b Discovered?
TOI-4145 A 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-4145 A b?
TOI-4145 A b is 669.9 light-years (205.4 parsecs) from Earth. Light arriving here tonight left the planet around the year 1357. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 11,790,240 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-4145 A b scores 0.07, ranking #4,886 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-4145 A
TOI-4145 A b belongs to a system of 2 stars; it orbits TOI-4145 A.
TOI-4145 A
- Surface temperature
- 5,281 K (Sun: 5,772 K)
- Mass
- 0.91 M☉
- Radius
- 0.86 R☉
- Luminosity
- 0.5160 L☉
- Age
- 4.7 billion years (Sun: 4.6)
Planetary System
TOI-4145 A b is the only planet known to orbit TOI-4145 A so far.
TOI-4145 A b — Complete Data
| Radius | 13.305 Earth radii (1.187 Jupiter radii) |
|---|---|
| Mass | 136.67 Earth masses (0.430 Jupiter masses) |
| Density | 0.32 g/cm³ (Earth: 5.51) |
| Orbital period | 4.07 days |
| Orbital distance | 0.048 AU |
| Equilibrium temperature | 1,074 K (801 °C) |
| Stellar irradiation | 223.00× Earth |
| Earth Similarity Index | 0.07 |
| Distance from Earth | 669.9 light-years (205.4 parsecs) |
| Constellation | Cepheus |
| 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-4145 A b
Is TOI-4145 A b habitable?
No — TOI-4145 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-4145 A b?
TOI-4145 A b is about 670 light-years from Earth in the constellation Cepheus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 11,790,240 years to get there.
How big is TOI-4145 A b compared to Earth?
TOI-4145 A b has 13.31 times the radius of Earth and about 137 times its mass.
How long is a year on TOI-4145 A b?
One orbit around TOI-4145 A takes 4.1 Earth days — short enough that 90 of its years would fit into one Earth year.
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