HATS-38 b
HATS-38 b is a hot Jupiter orbiting HATS-38 in the constellation Hydra. It lies about 1,120 light-years from Earth and was discovered in 2020 using the transit method.
How Big Is HATS-38 b?
HATS-38 b has a radius of 6.88 times that of Earth, or 0.61 times the radius of Jupiter. Its mass is 23.5 times that of Earth, giving it a density of 0.40 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is HATS-38 b in the Habitable Zone?
HATS-38 b orbits inside the inner edge of the habitable zone of HATS-38. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HATS-38: 0.817–1.927 AU (conservative: 1.035–1.827 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on HATS-38 b
The equilibrium temperature of HATS-38 b is about 1,294 K (1,021 °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 465 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on HATS-38 b — one full orbit around HATS-38 — lasts 4.38 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.
How Was HATS-38 b Discovered?
HATS-38 b was discovered in 2020 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-38 b?
HATS-38 b is 1,120.4 light-years (343.5 parsecs) from Earth. Light arriving here tonight left the planet about 1,120 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 19,719,040 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-38 b scores 0.12, ranking #4,330 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HATS-38
HATS-38
- Surface temperature
- 5,732 K (Sun: 5,772 K)
- Mass
- 0.89 M☉
- Radius
- 1.11 R☉
- Luminosity
- 1.1790 L☉
- Age
- 11.9 billion years (Sun: 4.6)
Planetary System
HATS-38 b is the only planet known to orbit HATS-38 so far.
HATS-38 b — Complete Data
| Radius | 6.882 Earth radii (0.614 Jupiter radii) |
|---|---|
| Mass | 23.52 Earth masses (0.074 Jupiter masses) |
| Density | 0.40 g/cm³ (Earth: 5.51) |
| Orbital period | 4.38 days |
| Orbital distance | 0.050 AU |
| Equilibrium temperature | 1,294 K (1,021 °C) |
| Stellar irradiation | 464.70× Earth |
| Earth Similarity Index | 0.12 |
| Distance from Earth | 1,120.4 light-years (343.5 parsecs) |
| Constellation | Hydra |
| Discovery method | Transit |
| Discovery facility | HATSouth |
| Discovery year | 2020 |
Data: NASA Exoplanet Archive, last updated 2020-08-06. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HATS-38 b
Is HATS-38 b habitable?
No — HATS-38 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HATS-38 b?
HATS-38 b is about 1,120 light-years from Earth in the constellation Hydra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 19,719,040 years to get there.
How big is HATS-38 b compared to Earth?
HATS-38 b has 6.88 times the radius of Earth and about 23.5 times its mass.
How long is a year on HATS-38 b?
One orbit around HATS-38 takes 4.4 Earth days — short enough that 83 of its years would fit into one Earth year.
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