astronomy

XO-4b

XO-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 XO-4b rather than just read about it. In short: XO-4b is an extrasolar planet approximately 956 light years away in the constellation of Lynx. This planet was found by the transit method by McCullough in May 2008.

Key takeaways

XO-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 XO-4b to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of XO-4b from memory before moving on to harder problems.

Reference excerpt

XO-4b is an extrasolar planet approximately 956 light years away in the constellation of Lynx. This planet was found by the transit method by McCullough in May 2008. The planet has mass 1.72 MJ and radius 1.34 RJ. This planet orbits very close to the F-type parent star, as it is typical for transiting planets, classing this planet as Hot Jupiter.

Orbit It takes only 4.125 days (or 99 hours) to orbit at a distance of 8.3 gigameters (0.0555 AU) away from the star. The study in 2012, utilizing a Rossiter–McLaughlin effect, have determined the planetary orbit is strongly misaligned with the equatorial plane of the star, misalignment equal to -46.7±8.1°.

Naming The planet XO-4b is named Hämarik. The name was selected in the NameExoWorlds campaign by Estonia, during the 100th anniversary of the IAU. Hämarik is Estonian for dusk, and was named for a character in a folk tale written by Friedrich Robert Faehlmann, alongside its host star XO-4, named Koit (dawn).

Illustrations

Worked examples

Example 1 — a first encounter with XO-4b

Start with the simplest possible case. Write down what XO-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 XO-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 XO-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 XO-4b

In research: XO-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 XO-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: XO-4b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exoplanet stubs, Exoplanets discovered in 2008, Exoplanets with proper names, so understanding it makes those chapters shorter.
In everyday life: Look for XO-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 XO-4b in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what XO-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 XO-4b out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is XO-4b in simple terms?

XO-4b is an extrasolar planet approximately 956 light years away in the constellation of Lynx. This planet was found by the transit method by McCullough in May 2008.

Why does XO-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 XO-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 XO-4b.