astronomy

WASP-4b

WASP-4b is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand WASP-4b rather than just read about it. In short: WASP-4b is an exoplanet, specifically a hot Jupiter, approximately 891 light-years away in the constellation of Phoenix. Discovery 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.

Key takeaways

WASP-4b belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect WASP-4b to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of WASP-4b from memory before moving on to harder problems.

Reference excerpt

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

Discovery 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 4,000 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.

Characteristics The planetary equilibrium temperature would be 1,650±30 K, but the measured dayside temperature is higher, with a 2015 study finding 1,900±100 K and a 2020 study finding 1,957±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 appeared 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 was poorly understood as of 2021. The orbital decay thought to be primarily driven by tidal interactions between the planet and its host star. However, in late 2025 it was determined that WASP-4b is not undergoing any orbital decay; all the data used to support it is instead explained by the light travel time effect of the wider-orbit planet WASP-4c.

References

Further reading 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.

External links 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.

Illustrations

Worked examples

Example 1 — a first encounter with WASP-4b

Start with the simplest possible case. Write down what WASP-4b claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to WASP-4b before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about WASP-4b ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of WASP-4b

In research: WASP-4b appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses WASP-4b in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: WASP-4b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exoplanets discovered by WASP, Exoplanets discovered in 2007, Giant planets, so understanding it makes those chapters shorter.
In everyday life: Look for WASP-4b outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study WASP-4b in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what WASP-4b means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain WASP-4b out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is WASP-4b in simple terms?

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

Why does WASP-4b matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study WASP-4b?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on WASP-4b.