WASP-4
G-type main-sequence star in the constellation Phoenix
WASP-4 is a G-type main-sequence star approximately 891 light-years away in the constellation of Phoenix. Despite its advanced age, the star is rotating rapidly, being spun up by the tides raised by a giant planet on a close orbit.
01Planetary system
In 2007 the exoplanet WASP-4b was discovered orbiting this star. With an orbital period of just 1.3 days, it is classified as a hot Jupiter. The planet's orbital period appears to be decreasing at a rate of 7.33±0.71 milliseconds per year, suggesting that its orbit is decaying, with a decay timescale of 15.77±1.57 million years. Another superjovian planet in the system has been suspected. A 2025 study further supported orbital decay for WASP-4b, but another same-year study discounted this, attributing all evidence for orbital decay to the light travel time effect of an outer planet. Although the previous candidate has not been addressed, this planet has nearly the same orbital elements and thus both should be the same object.
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| b | 1.200+0.032 −0.030 MJ |
0.02294+0.00028 −0.00026 |
1.338230994(84) | 0.0013+0.0005 −0.0009 |
88.05+0.85 −0.53 |
1.349+0.011 −0.012 RJ |
| c | ≥6.93+1.10 −0.47 MJ |
7.96+0.72 −0.32 |
8,650+1,200 −510 |
, | , | , |
Sources and credits
This article is adapted from the Wikipedia article “WASP-4”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- Planet WASP-4.png by Tyrogthekreeper at en.wikipedia, CC BY-SA 3.0
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