astronomy

S Coronae Borealis

S Coronae Borealis 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 S Coronae Borealis rather than just read about it. In short: S Coronae Borealis (S CrB) is a Mira variable star in the constellation Corona Borealis located about 1,400 light-years away. Its apparent magnitude varies between 5.3 and 13.6, with a period of 360 days, representing about a 2000–fold change in brightness.

Key takeaways

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

Reference excerpt

S Coronae Borealis (S CrB) is a Mira variable star in the constellation Corona Borealis located about 1,400 light-years away. Its apparent magnitude varies between 5.3 and 13.6, with a period of 360 days, representing about a 2000–fold change in brightness. Within the constellation, it lies to the west of Theta Coronae Borealis, and around 1 degree southeast of the eclipsing binary star U Coronae Borealis. When it is near its maximum brightness, it can be seen with the naked eye, under good observing conditions. With a typical local maximum magnitude around 7, S Coronae Borealis' is on average brighter than T Coronae Borealis or W Coronae Borealis.

Variability

S Coronae Borealis was discovered to vary in brightness by German amateur astronomer Karl Ludwig Hencke in 1860. It was classified as a long period variable star as other similar objects were discovered, and later as a Mira variable. The maximum range of variation is from magnitude 5.3 to 13.6 although individual maxima and minima can vary in brightness. The period of 360 days is fairly predictable.

Properties S Coronae Borealis is a cool red giant on the asymptotic giant branch (AGB). It pulsates, which causes its radius and temperature to change. One calculation found a temperature range of 2,350 K to 2,600 K, although a more modern calculation gives a temperature of 2,864 K. Similarly a calculation of the varying radius gives 537 to 664 R☉ although a modern calculation of the radius gives 308 R☉. The bolometric luminosity varies much less than the visual magnitude and is estimated to be 5,623 L☉. Its parallax has been measured by very-long-baseline interferometry (VLBI), yielding a result of 2.39±0.17 mas, which converts to a distance of 1,300±100 light-years. The masses of AGB stars are poorly known and cannot be calculated from their physical properties, but they can be estimated using asteroseismology. The pulsations of S Coronae Borealis lead to a mass estimate of 1.34 times that of the Sun.

References

External links S CrB lightcurve at AAVSO

Illustrations

Worked examples

Example 1 — a first encounter with S Coronae Borealis

Start with the simplest possible case. Write down what S Coronae Borealis 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 S Coronae Borealis 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 S Coronae Borealis 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 S Coronae Borealis

In research: S Coronae Borealis 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 S Coronae Borealis 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: S Coronae Borealis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Corona Borealis, Durchmusterung objects, Emission-line stars, so understanding it makes those chapters shorter.
In everyday life: Look for S Coronae Borealis 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 S Coronae Borealis in 20 minutes

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

Frequently asked questions

What is S Coronae Borealis in simple terms?

Why does S Coronae Borealis 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 S Coronae Borealis?

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 S Coronae Borealis.