science

Westerlund 1-20

Westerlund 1-20 is a science 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 Westerlund 1-20 rather than just read about it. In short: Westerlund 1-20 (abbreviated to Wd 1-20 or just W20) is a red supergiant (RSG) located in the Westerlund 1 super star cluster. Its radius was calculated to be around 965 solar radii (6.72 × 108 km, 4.48 au), making it one of the largest stars discovered so far.

Key takeaways

Westerlund 1-20 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Westerlund 1-20 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Westerlund 1-20 from memory before moving on to harder problems.

Reference excerpt

Westerlund 1-20 (abbreviated to Wd 1-20 or just W20) is a red supergiant (RSG) located in the Westerlund 1 super star cluster. Its radius was calculated to be around 965 solar radii (6.72 × 108 km, 4.48 au), making it one of the largest stars discovered so far. This corresponds to a volume 899 million times bigger than the Sun. If placed at the center of the Solar System, the photosphere of Westerlund 1-20 would almost reach the orbit of Jupiter.

The star is classified as a luminous cool supergiant emitting most of its energy in the infrared spectrum. W20 occupies the upper right corner of the Hertzsprung-Russell diagram. Using the effective temperature of 3,500 K, the bolometric luminosity of 126,000 L☉ and the solar effective temperature of 5,772 K, its radius can be calculated using the Stefan-Boltzmann law. Westerlund 1-20 was observed to have an extended, cometary shaped nebula, similar to the other red supergiant Westerlund 1 W26. It is therefore likely that its morphology was affected by either the intracluster medium or the cluster wind of Westerlund 1. The nebulae of both Westerlund 1-20 and Westerlund 1 W26 are extended outward from the cluster core and most bright at inward direction, indicating the outward cluster wind.

See also Westerlund 1-237 Westerlund 1-75 List of largest known stars

Notes

References

Illustrations

Worked examples

Example 1 — a first encounter with Westerlund 1-20

Start with the simplest possible case. Write down what Westerlund 1-20 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Westerlund 1-20 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 Westerlund 1-20 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 Westerlund 1-20

In research: Westerlund 1-20 appears in science 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 Westerlund 1-20 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: Westerlund 1-20 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Ara (constellation), M-type supergiants, so understanding it makes those chapters shorter.
In everyday life: Look for Westerlund 1-20 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 Westerlund 1-20 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Westerlund 1-20 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 Westerlund 1-20 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Westerlund 1-20 in simple terms?

Why does Westerlund 1-20 matter?

Because it connects several science 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 Westerlund 1-20?

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 Westerlund 1-20.