astronomy

NGC 547

NGC 547 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 547 rather than just read about it. In short: NGC 547 is an elliptical galaxy and radio galaxy (identified as 3C 40) located in the constellation Cetus. It is located at a distance of about 214 million light years from Earth, which, given its apparent dimensions, means that NGC 547 is about 147,000 light years across.

Key takeaways

NGC 547 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 547 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 547 from memory before moving on to harder problems.

Reference excerpt

NGC 547 is an elliptical galaxy and radio galaxy (identified as 3C 40) located in the constellation Cetus. It is located at a distance of about 214 million light years from Earth, which, given its apparent dimensions, means that NGC 547 is about 147,000 light years across. It was discovered by German-British astronomer William Herschel on October 1, 1785. It is a member of the Abell 194 galaxy cluster and is included along with NGC 547 in the Atlas of Peculiar Galaxies. NGC 547 is a prominent radio galaxy, with two large radio jets of Fanaroff-Riley class I with wide-angle tails. The galaxy is identified as 3C 40B (3C 40A is less prominent and is associated with the nearby galaxy NGC 541), and the source extends for 10 arcminutes in the south–north direction. A small, smooth, dark feature has been observed running across the nucleus in images by the Hubble Space Telescope. Its projected size is 0.3 kpc and its shape suggests it is the near side of a small dust disk. NGC 547 forms a pair with the equally bright NGC 545, which lies 0.5 arcminutes away. They share a common envelope, however, despite their close position, no tidal features like tails or bridges have been observed. A stellar bridge has been detected between the galaxy pair and NGC 541, which lies 4.5 arcminutes to the southwest (projected distance circa 100 kpc). Observations of the galaxy by the Chandra X-Ray Observatory revealed a large very luminous X-ray corona around the galaxy. The gas distribution appears symmetric, without evidence of tails, indicating its relatively low velocity, and thus it has been identified as the centre of the cluster, with NGC 541 and NGC 545 moving towards it.

References

External links Media related to NGC 547 at Wikimedia Commons NGC 547 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images NGC 547 on SIMBAD

Illustrations

Worked examples

Example 1 — a first encounter with NGC 547

Start with the simplest possible case. Write down what NGC 547 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 547 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 547 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 547

In research: NGC 547 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 547 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 547 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 3C objects, Arp objects, Astronomical objects discovered in 1785, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 547 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 547 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 547 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 547 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 547 in simple terms?

Why does NGC 547 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 547?

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 547.