HATS-22 b
HATS-22 b is a hot Jupiter orbiting the K V star HATS-22 in the constellation Hydra. It lies about 749 light-years from Earth and was discovered in 2017 using the transit method.
How Big Is HATS-22 b?
HATS-22 b has a radius of 10.68 times that of Earth, or 0.95 times the radius of Jupiter. Its mass is 871 times that of Earth, giving it a density of 3.89 g/cm³ — between that of rocky and gaseous planets.
Is HATS-22 b in the Habitable Zone?
HATS-22 b orbits inside the inner edge of the habitable zone of HATS-22. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HATS-22: 0.376–0.916 AU (conservative: 0.476–0.868 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on HATS-22 b
The equilibrium temperature of HATS-22 b is about 858 K (585 °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.
Orbit and Year Length
A year on HATS-22 b — one full orbit around HATS-22 — lasts 4.72 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.050 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.08).
How Was HATS-22 b Discovered?
HATS-22 b was discovered in 2017 using the transit method, with observations from HATSouth.
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 HATS-22 b?
HATS-22 b is 748.6 light-years (229.5 parsecs) from Earth. Light arriving here tonight left the planet around the year 1278. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 13,175,360 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. HATS-22 b scores 0.09, ranking #4,488 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HATS-22
HATS-22
- Spectral type
- K V
- Surface temperature
- 4,803 K (Sun: 5,772 K)
- Mass
- 0.76 M☉
- Radius
- 0.69 R☉
- Luminosity
- 0.2260 L☉
Planetary System
HATS-22 b is the only planet known to orbit HATS-22 so far.
HATS-22 b — Complete Data
| Radius | 10.682 Earth radii (0.953 Jupiter radii) |
|---|---|
| Mass | 870.85 Earth masses (2.740 Jupiter masses) |
| Density | 3.89 g/cm³ (Earth: 5.51) |
| Orbital period | 4.72 days |
| Orbital distance | 0.050 AU |
| Eccentricity | 0.079 |
| Equilibrium temperature | 858 K (585 °C) |
| Earth Similarity Index | 0.09 |
| Distance from Earth | 748.6 light-years (229.5 parsecs) |
| Constellation | Hydra |
| Discovery method | Transit |
| Discovery facility | HATSouth |
| Discovery year | 2017 |
Data: NASA Exoplanet Archive, last updated 2017-03-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HATS-22 b
Is HATS-22 b habitable?
No — HATS-22 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HATS-22 b?
HATS-22 b is about 749 light-years from Earth in the constellation Hydra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 13,175,360 years to get there.
How big is HATS-22 b compared to Earth?
HATS-22 b has 10.68 times the radius of Earth and about 871 times its mass.
How long is a year on HATS-22 b?
One orbit around HATS-22 takes 4.7 Earth days — short enough that 77 of its years would fit into one Earth year.
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