astronomy

WR 136

WR 136 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 WR 136 rather than just read about it. In short: WR 136 is a Wolf–Rayet star located in the constellation Cygnus. It is in the center of the Crescent Nebula.

Key takeaways

WR 136 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect WR 136 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of WR 136 from memory before moving on to harder problems.

Reference excerpt

WR 136 is a Wolf–Rayet star located in the constellation Cygnus. It is in the center of the Crescent Nebula. Its age is estimated to be around 4.7 million years and it is nearing the end of its life. Within a few hundred thousand years, it is expected to explode as a supernova. According to recent estimations, WR 136 is 600,000 times brighter than the Sun, 21 times more massive, and 5.1 times larger. Its surface temperature is around 70,000 kelvins. WR 136 blew off a shell of material with a mass of around 5 M☉ when it became a red supergiant around 120,000–240,000 years ago and this is still expanding at 80 km/s. Currently, its fast stellar wind, ejected from the star at around 3.8 million mph (1,700 km/s), is catching up to the material ejected from the star and shaping it into a shell. Ultraviolet rays emitted from WR 136's hot surface cause the shell to glow. There is some evidence WR 136 may be a binary star. Its companion would be a low-mass star of spectral classification K or M that would complete an orbit around the Wolf-Rayet star each 5.13 days, being the progenitor of a low-mass X-ray binary system.

References

Further reading Bychkov, K. V.; Sitnik, T. G. (2006). "Stratification of optical emission from NGC 6888 as a trace of the interaction between Wolf-Rayet stellar wind and the shell of a red supergiant". Astronomy Letters. 32 (6): 406. Bibcode:2006AstL...32..406B. doi:10.1134/S1063773706060041. S2CID 123039046.

External links https://chandra.harvard.edu/photo/2003/ngc6888/ https://www.giga-parsec.de/WRspectra.html https://www.castfvg.it/stelle/spettri/O/wr_136_01.htm

Illustrations

Worked examples

Example 1 — a first encounter with WR 136

Start with the simplest possible case. Write down what WR 136 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 WR 136 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 WR 136 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 WR 136

In research: WR 136 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 WR 136 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: WR 136 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cygnus (constellation), Durchmusterung objects, Henry Draper Catalogue objects, so understanding it makes those chapters shorter.
In everyday life: Look for WR 136 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 WR 136 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what WR 136 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 WR 136 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is WR 136 in simple terms?

WR 136 is a Wolf–Rayet star located in the constellation Cygnus. It is in the center of the Crescent Nebula.

Why does WR 136 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 WR 136?

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 WR 136.