astronomy

NGC 4747

NGC 4747 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 NGC 4747 rather than just read about it. In short: NGC 4747 is a barred spiral galaxy located in the constellation Coma Berenices. It is located at a distance of about 35 million light years from Earth, which, given its apparent dimensions, means that NGC 4747 is about 35,000 light years across.

Key takeaways

NGC 4747 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect NGC 4747 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 4747 from memory before moving on to harder problems.

Reference excerpt

NGC 4747 is a barred spiral galaxy located in the constellation Coma Berenices. It is located at a distance of about 35 million light years from Earth, which, given its apparent dimensions, means that NGC 4747 is about 35,000 light years across. It was discovered by William Herschel on April 6, 1785. It is included in the Atlas of Peculiar Galaxies in the interior absorption category. The galaxy is a member of the Coma I Group, which is part of the Local Supercluster. NGC 4747 is interacting with neighboring spiral galaxy NGC 4725, with its spiral arms showing indications of warping. The pair have an angular separation of 24′, which corresponds to a projected linear separation of 370 kly. A close approach between NGC 4747 and the more massive NGC 4725 that took place 320 million years before observed created tidal plumes in NGC 4747. A short tidal plume extends from NGC 4747 toward NGC 4725, to the south-west, and one more pronounced towards the north-east, with a length of 8 arcminutes. The optical north-east plume has also a hydrogen counterpart, which is offset by 50 degrees from the visual counterpart. Two knots, possibly star clusters, are visible in the northeast plume, that could become tidal dwarf galaxies, as they appear to be massive enough to be self-gravitating. The star formation rate of the galaxy is estimated to be 0.13 solar masses per year.

References

External links

NGC 4747 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images NGC 4747 on SIMBAD

Illustrations

Worked examples

Example 1 — a first encounter with NGC 4747

Start with the simplest possible case. Write down what NGC 4747 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 NGC 4747 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 NGC 4747 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 NGC 4747

In research: NGC 4747 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 NGC 4747 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: NGC 4747 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Arp objects, Barred spiral galaxies, Coma Berenices, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 4747 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 NGC 4747 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 4747 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 NGC 4747 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 4747 in simple terms?

Why does NGC 4747 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 NGC 4747?

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 NGC 4747.