WASP-4
G-type main sequence star in the constellation Phoenix
From Wikipedia, the free encyclopedia
WASP-4 is a G-type main-sequence star approximately 891 light-years away in the constellation of Phoenix.[4][1][2] Despite its advanced age, the star is rotating rapidly, being spun up by the tides raised by a giant planet on a close orbit.[8]
Artistic rendering of WASP-4 b | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Phoenix[1] |
| Right ascension | 23h 34m 15.0857s[2] |
| Declination | −42° 03′ 41.048″[2] |
| Apparent magnitude (V) | 12.468±0.025[3] |
| Characteristics | |
| Evolutionary stage | Main sequence[2] |
| Spectral type | G7V[4] |
| Apparent magnitude (V) | 12.468±0.025[3] |
| Apparent magnitude (B) | 13.216±0.020[3] |
| Variable type | Planetary transit variable[4] |
| Astrometry | |
| Radial velocity (Rv) | 57.61±0.76[2] km/s |
| Proper motion (μ) | RA: 9.950(12) mas/yr[2] Dec.: −87.620(10) mas/yr[2] |
| Parallax (π) | 3.6623±0.0147 mas[2] |
| Distance | 891 ± 4 ly (273 ± 1 pc) |
| Details | |
| Mass | 0.899+0.033 −0.031[5] M☉ |
| Radius | 0.9150+0.0089 −0.0091[5] R☉ |
| Surface gravity (log g) | 4.472+0.013 −0.012[5] cgs |
| Temperature | 5488+29 −28[5] K |
| Metallicity [Fe/H] | −0.050±0.040[6] dex |
| Rotation | 22.2±3.3[6] days |
| Rotational velocity (v sin i) | 2.2+0.6 −1.0[6] km/s |
| Age | 7.0±2.9[6] Gyr |
| Other designations | |
| 1SWASP J233415.06-420341.1, TOI-232, TIC 402026209, WASP-4, TYC 8017-108-1, 2MASS J23341508-4203411[7] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
Planetary 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.[4] 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.[9] Another superjovian planet in the system has been suspected.[9] A 2025 study further supported orbital decay for WASP-4b,[5] but another same-year study discounted this, attributing all evidence for orbital decay to the light travel time effect of an outer planet.[10] Although the previous candidate has not been addressed, this planet has nearly the same orbital elements and thus both should be the same object.[10]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b[5] | 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[10] | ≥6.93+1.10 −0.47 MJ |
7.96+0.72 −0.32 |
8,650+1,200 −510 |
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