astronomy

XO-3

XO-3 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-3 rather than just read about it. In short: XO-3 is a star 670 light-years (210 parsecs) away in the constellation Camelopardalis. The star has a magnitude of 10 and is not visible to the naked eye but is visible through a small telescope.

Key takeaways

XO-3 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-3 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of XO-3 from memory before moving on to harder problems.

Reference excerpt

XO-3 is a star 670 light-years (210 parsecs) away in the constellation Camelopardalis. The star has a magnitude of 10 and is not visible to the naked eye but is visible through a small telescope. A search for a binary companion star using adaptive optics at the MMT Observatory was negative.

Planetary system In 2007, the gas giant exoplanet XO-3b was discovered by the XO Telescope using the transit method. This object may be classified as a brown dwarf because of its high mass, near the ~13 MJ limit for deuterium fusion. The planetary orbit is misaligned with the stellar rotation, which is unusual for such a massive planet. The misalignment may be due to an undetected companion star.

References

Further reading Winn, Joshua N.; et al. (2008). "The Transit Light Curve Project. IX. Evidence for a Smaller Radius of the Exoplanet XO-3b". The Astrophysical Journal. 683 (2): 1076–1084. arXiv:0804.4475. Bibcode:2008ApJ...683.1076W. doi:10.1086/589737. S2CID 119266744.

Worked examples

Example 1 — a first encounter with XO-3

Start with the simplest possible case. Write down what XO-3 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-3 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-3 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-3

In research: XO-3 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-3 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-3 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Camelopardalis, Durchmusterung objects, F-type main-sequence stars, so understanding it makes those chapters shorter.
In everyday life: Look for XO-3 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-3 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what XO-3 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-3 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is XO-3 in simple terms?

XO-3 is a star 670 light-years (210 parsecs) away in the constellation Camelopardalis. The star has a magnitude of 10 and is not visible to the naked eye but is visible through a small telescope.

Why does XO-3 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-3?

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-3.