XO-4 b
XO-4 b is a hot Jupiter orbiting XO-4 in the constellation Lynx. It lies about 889 light-years from Earth and was discovered in 2010 using the transit method.
How Big Is XO-4 b?
XO-4 b has a radius of 14.01 times that of Earth, or 1.25 times the radius of Jupiter. Its mass is 451 times that of Earth.
Is XO-4 b in the Habitable Zone?
The position of XO-4 b relative to the habitable zone of XO-4 cannot be precisely determined from the available orbital data.
Habitable zone of XO-4: 1.285–2.987 AU (conservative: 1.627–2.832 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Orbit and Year Length
A year on XO-4 b — one full orbit around XO-4 — lasts 4.13 Earth days, shorter than Mercury's 88-day year.
How Was XO-4 b Discovered?
XO-4 b was discovered in 2010 using the transit method, with observations from Lowell Observatory.
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 XO-4 b?
XO-4 b is 889.3 light-years (272.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1137. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 15,651,680 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. XO-4 b scores 0.07, ranking #5,052 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: XO-4
XO-4
- Surface temperature
- 6,397 K (Sun: 5,772 K)
- Mass
- 1.10 M☉
- Radius
- 1.45 R☉
Planetary System
XO-4 b is the only planet known to orbit XO-4 so far.
XO-4 b — Complete Data
| Radius | 14.011 Earth radii (1.250 Jupiter radii) |
|---|---|
| Mass | 451.32 Earth masses (1.420 Jupiter masses) |
| Orbital period | 4.13 days |
| Earth Similarity Index | 0.07 |
| Distance from Earth | 889.3 light-years (272.7 parsecs) |
| Constellation | Lynx |
| Discovery method | Transit |
| Discovery facility | Lowell Observatory |
| Discovery year | 2010 |
Data: NASA Exoplanet Archive, last updated 2018-04-25. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About XO-4 b
Is XO-4 b habitable?
XO-4 b is not known to orbit within the habitable zone of XO-4, and as a hot Jupiter it is an unlikely candidate for life as we know it.
How far away is XO-4 b?
XO-4 b is about 889 light-years from Earth in the constellation Lynx. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 15,651,680 years to get there.
How big is XO-4 b compared to Earth?
XO-4 b has 14.01 times the radius of Earth and about 451 times its mass.
How long is a year on XO-4 b?
One orbit around XO-4 takes 4.1 Earth days — short enough that 89 of its years would fit into one Earth year.
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