Qatar-4 b
Qatar-4 b is a hot Jupiter orbiting the K1 V star Qatar-4 in the constellation Andromeda. It lies about 1,073 light-years from Earth and was discovered in 2017 using the transit method.
How Big Is Qatar-4 b?
Qatar-4 b has a radius of 12.72 times that of Earth, or 1.14 times the radius of Jupiter. Its mass is 1,939 times that of Earth, giving it a density of 5.10 g/cm³ — comparable to rocky planets like Earth (5.51 g/cm³).
Is Qatar-4 b in the Habitable Zone?
Qatar-4 b orbits inside the inner edge of the habitable zone of Qatar-4. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Qatar-4: 0.537–1.289 AU (conservative: 0.681–1.222 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on Qatar-4 b
The equilibrium temperature of Qatar-4 b is about 1,385 K (1,112 °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 614 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on Qatar-4 b — one full orbit around Qatar-4 — lasts just 43.3 hours, shorter than Mercury's 88-day year. It orbits at an average distance of 0.028 AU — closer to its star than Mercury is to the Sun.
How Was Qatar-4 b Discovered?
Qatar-4 b was discovered in 2017 using the transit method, with observations from Qatar.
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 Qatar-4 b?
Qatar-4 b is 1,073.2 light-years (329.0 parsecs) from Earth. Light arriving here tonight left the planet about 1,073 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 18,888,320 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. Qatar-4 b scores 0.07, ranking #4,895 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Qatar-4
Qatar-4
- Spectral type
- K1 V
- Surface temperature
- 5,215 K (Sun: 5,772 K)
- Mass
- 0.90 M☉
- Radius
- 0.85 R☉
- Luminosity
- 0.4810 L☉
- Age
- 0.2 billion years (Sun: 4.6)
Planetary System
Qatar-4 b is the only planet known to orbit Qatar-4 so far.
Qatar-4 b — Complete Data
| Radius | 12.722 Earth radii (1.135 Jupiter radii) |
|---|---|
| Mass | 1,938.76 Earth masses (6.100 Jupiter masses) |
| Density | 5.10 g/cm³ (Earth: 5.51) |
| Orbital period | 1.81 days |
| Orbital distance | 0.028 AU |
| Equilibrium temperature | 1,385 K (1,112 °C) |
| Stellar irradiation | 614.00× Earth |
| Earth Similarity Index | 0.07 |
| Distance from Earth | 1,073.2 light-years (329.0 parsecs) |
| Constellation | Andromeda |
| Discovery method | Transit |
| Discovery facility | Qatar |
| Discovery year | 2017 |
Data: NASA Exoplanet Archive, last updated 2017-04-24. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Qatar-4 b
Is Qatar-4 b habitable?
No — Qatar-4 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Qatar-4 b?
Qatar-4 b is about 1,073 light-years from Earth in the constellation Andromeda. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 18,888,320 years to get there.
How big is Qatar-4 b compared to Earth?
Qatar-4 b has 12.72 times the radius of Earth and about 1,939 times its mass.
How long is a year on Qatar-4 b?
One orbit around Qatar-4 takes 1.8 Earth days — short enough that 202 of its years would fit into one Earth year.
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