WASP-4b

WASP-4b is an exoplanet, specifically a hot Jupiter, approximately 891 light-years away in the constellation of Phoenix.

The planet was the discovered by the Wide Angle Search for Planets team using images taken with the SuperWASP-South project's eight wide-angle cameras located at the South African Astronomical Observatory. Analysis of over 4000 images taken between May and November 2006 resulted in the detection of a transit occurring every 1.3 days. Follow-up radial velocity observations using the Swiss 1.2-metre Leonhard Euler Telescope confirmed that the transiting object was a planet.

The planetary equilibrium temperature would be 1650±30 K, but the measured dayside temperature is higher, with a 2015 study finding 1900±100 K and a 2020 study finding 1957±68 K.

A study in 2012, utilizing the Rossiter–McLaughlin effect, determined the planetary orbit is probably aligned with the equatorial plane of the star, with misalignment equal to -1⁺¹⁴
₋₁₂°.

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. The anomalously high rate of orbital decay of WASP-4b is poorly understood as of 2021.

• Petrucci, R.; et al. (2013). "No Transit Timing Variations in Wasp-4". The Astrophysical Journal Letters. 779 (2). L23. arXiv:1311.2048. Bibcode:2013ApJ...779L..23P. doi:10.1088/2041-8205/779/2/L23. S2CID 118376692.
• Huitson, C. M.; et al. (2017). "Gemini/GMOS Transmission Spectral Survey: Complete Optical Transmission Spectrum of the Hot Jupiter WASP-4b". The Astronomical Journal. 154 (3). 95. arXiv:1707.06575. Bibcode:2017AJ....154...95H. doi:10.3847/1538-3881/aa7f72. S2CID 119415111.
• Bouma, L. G.; Winn, J. N.; et al. (June 2019). "WASP-4b Arrived Early for the TESS Mission". The Astronomical Journal. 157 (6): 217. arXiv:1903.02573. Bibcode:2019AJ....157..217B. doi:10.3847/1538-3881/ab189f.

Media related to WASP-4b at Wikimedia Commons

• "Transiting exoplanets from the Wide Angle Search for Planets". WASP Planets. Coel Hellier. Retrieved 2020-12-27.
• "UK planet hunters announce three new finds" (PDF). 2007-10-30. Archived from the original (PDF) on 2008-05-16. Retrieved 2008-07-02.