TOI-620 b
TOI-620 b is a sub-Neptune orbiting the M2.5 V star TOI-620 in the constellation Hydra. It lies about 108 light-years from Earth and was discovered in 2022 using the transit method.
How Big Is TOI-620 b?
TOI-620 b has a radius of 3.76 times that of Earth.
Is TOI-620 b in the Habitable Zone?
TOI-620 b orbits inside the inner edge of the habitable zone of TOI-620. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-620: 0.185–0.475 AU (conservative: 0.234–0.451 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-620 b
The equilibrium temperature of TOI-620 b is about 604 K (330 °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 20.80 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-620 b — one full orbit around TOI-620 — lasts 5.10 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. Its orbit is mildly elliptical (eccentricity 0.22).
How Was TOI-620 b Discovered?
TOI-620 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.
How Far Away Is TOI-620 b?
TOI-620 b is 107.7 light-years (33.0 parsecs) from Earth. Light arriving here tonight left the planet around the year 1919. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 1,895,520 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-620 b scores 0.23, ranking #3,442 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-620
TOI-620
- Spectral type
- M2.5 V
- Surface temperature
- 3,708 K (Sun: 5,772 K)
- Mass
- 0.58 M☉
- Radius
- 0.55 R☉
- Luminosity
- 0.0515 L☉
- Age
- 7.2 billion years (Sun: 4.6)
Planetary System
TOI-620 b is the only planet known to orbit TOI-620 so far.
TOI-620 b — Complete Data
| Radius | 3.760 Earth radii (0.335 Jupiter radii) |
|---|---|
| Orbital period | 5.10 days |
| Orbital distance | 0.048 AU |
| Eccentricity | 0.220 |
| Equilibrium temperature | 604 K (330 °C) |
| Stellar irradiation | 20.80× Earth |
| Earth Similarity Index | 0.23 |
| Distance from Earth | 107.7 light-years (33.0 parsecs) |
| Constellation | Hydra |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2022 |
Data: NASA Exoplanet Archive, last updated 2022-04-12. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-620 b
Is TOI-620 b habitable?
No — TOI-620 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-620 b?
TOI-620 b is about 108 light-years from Earth in the constellation Hydra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 1,895,520 years to get there.
How big is TOI-620 b compared to Earth?
TOI-620 b has 3.76 times the radius of Earth.
How long is a year on TOI-620 b?
One orbit around TOI-620 takes 5.1 Earth days — short enough that 72 of its years would fit into one Earth year.
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