astronomy

R136c

R136c 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 R136c rather than just read about it. In short: R136c is a likely binary star located in R136, a tight knot of stars at the centre of NGC 2070, an open cluster weighing 450,000 solar masses and containing 10,000 stars. At 142 M☉ and 3.8 million L☉, it is one of the most massive stars known and one of the most luminous, along with being one of the hottest, at over 40,000 K.

Key takeaways

R136c belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect R136c to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of R136c from memory before moving on to harder problems.

Reference excerpt

R136c is a likely binary star located in R136, a tight knot of stars at the centre of NGC 2070, an open cluster weighing 450,000 solar masses and containing 10,000 stars. At 142 M☉ and 3.8 million L☉, it is one of the most massive stars known and one of the most luminous, along with being one of the hottest, at over 40,000 K. It was first resolved and named by Feitzinger in 1980, along with R136a and R136b.

Description R136c is a Wolf–Rayet star of the spectral type WN5h and with a temperature of 42,170 K, making it one of hottest stars known. It is one of the most massive stars known, with a mass of 142 M☉, and it is one of the most luminous stars known, with a luminosity of 3.8 million L☉. The extreme luminosity is produced by the CNO fusion process in its highly compressed hot core. Typical of all Wolf–Rayet stars, R136c has been losing mass by means of a strong stellar wind with speeds over 2,000 km/s and mass loss rates in excess of 10−5 solar masses per year. It is strongly suspected to be a binary, due to the detection of hard x-ray emission typical of colliding wind binaries, but the companion is thought to make only a small contribution to the total luminosity. Absorption lines in the spectrum, tentatively assigned to the companion, indicate that it is considerably more massive than the Wolf-Rayet component. An orbit has been derived, but with low confidence and even the period is uncertain, between 5 and 47 days.

Evolution R136c is so energetic that it has already lost a substantial fraction of its initial mass, even though it is only a few million years old. It is still effectively on the main sequence, fusing hydrogen at its core via the CNO cycle, but it has convected and mixed fusion products to the surface and these create a powerful stellar wind and emission spectrum normally only seen in highly evolved stars. Its fate depends on the amount of mass it loses before its core collapses, but is likely to result in a supernova. The most recent models for single star evolution at near-solar metallicities suggest that the most massive stars explode as highly stripped type Ic supernovae, although different outcomes are possible for binaries. Some of these supernovae are expected to produce a type of gamma-ray burst and the expected remnant is a black hole.

References

Illustrations

Worked examples

Example 1 — a first encounter with R136c

Start with the simplest possible case. Write down what R136c 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 R136c 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 R136c 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 R136c

In research: R136c 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 R136c 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: R136c is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1980, Dorado, Stars in the Large Magellanic Cloud, so understanding it makes those chapters shorter.
In everyday life: Look for R136c 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 R136c in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what R136c 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 R136c out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is R136c in simple terms?

Why does R136c 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 R136c?

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 R136c.