HATS-4 b
HATS-4 b is a hot Jupiter orbiting the G star HATS-4 in the constellation Canis Major. It lies about 1,358 light-years from Earth and was discovered in 2014 using the transit method.
How Big Is HATS-4 b?
HATS-4 b has a radius of 11.43 times that of Earth, or 1.02 times the radius of Jupiter. Its mass is 420 times that of Earth, giving it a density of 1.55 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is HATS-4 b in the Habitable Zone?
HATS-4 b orbits inside the inner edge of the habitable zone of HATS-4. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HATS-4: 0.618–1.473 AU (conservative: 0.783–1.397 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on HATS-4 b
The equilibrium temperature of HATS-4 b is about 1,315 K (1,042 °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-4 b — one full orbit around HATS-4 — lasts 2.52 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.036 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.013).
How Was HATS-4 b Discovered?
HATS-4 b was discovered in 2014 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-4 b?
HATS-4 b is 1,358.3 light-years (416.5 parsecs) from Earth. Light arriving here tonight left the planet about 1,358 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 23,906,080 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-4 b scores 0.08, ranking #4,685 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HATS-4
HATS-4
- Spectral type
- G
- Surface temperature
- 5,403 K (Sun: 5,772 K)
- Mass
- 1.00 M☉
- Radius
- 0.93 R☉
- Luminosity
- 0.6501 L☉
- Age
- 2.1 billion years (Sun: 4.6)
Planetary System
HATS-4 b is the only planet known to orbit HATS-4 so far.
HATS-4 b — Complete Data
| Radius | 11.433 Earth radii (1.020 Jupiter radii) |
|---|---|
| Mass | 420.47 Earth masses (1.323 Jupiter masses) |
| Density | 1.55 g/cm³ (Earth: 5.51) |
| Orbital period | 2.52 days |
| Orbital distance | 0.036 AU |
| Eccentricity | 0.013 |
| Equilibrium temperature | 1,315 K (1,042 °C) |
| Earth Similarity Index | 0.08 |
| Distance from Earth | 1,358.3 light-years (416.5 parsecs) |
| Constellation | Canis Major |
| Discovery method | Transit |
| Discovery facility | HATSouth |
| Discovery year | 2014 |
Data: NASA Exoplanet Archive, last updated 2014-07-02. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HATS-4 b
Is HATS-4 b habitable?
No — HATS-4 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HATS-4 b?
HATS-4 b is about 1,358 light-years from Earth in the constellation Canis Major. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 23,906,080 years to get there.
How big is HATS-4 b compared to Earth?
HATS-4 b has 11.43 times the radius of Earth and about 420 times its mass.
How long is a year on HATS-4 b?
One orbit around HATS-4 takes 2.5 Earth days — short enough that 145 of its years would fit into one Earth year.
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