astronomy

NGC 4197

NGC 4197 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 4197 rather than just read about it. In short: NGC 4197 is a spiral galaxy in the constellation Virgo. The galaxy lies about 90 million light years away from Earth, which means, given its apparent dimensions, that NGC 4197 is approximately 100,000 light years across.

Key takeaways

NGC 4197 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 4197 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 4197 from memory before moving on to harder problems.

Reference excerpt

NGC 4197 is a spiral galaxy in the constellation Virgo. The galaxy lies about 90 million light years away from Earth, which means, given its apparent dimensions, that NGC 4197 is approximately 100,000 light years across. It was discovered by William Herschel on April 13, 1784.

Characteristics NGC 4197 is a spiral galaxy seen nearly edge-on, at an angle of 79°. Two faint plumes are visible in H-alpha in the galactic halo southeast of the galaxy, extending for about 5 kiloparsec. The observed plumes are probably associated with HII regions in the disk. About 13% of the H-alpha emission of the galaxy comes from extraplanar gas, with an estimated mass of 1.0×108 M☉. The star formation rate of the galaxy is estimated to be about 1 M☉ per year. A strong point-like X-ray source has been detected at the centre of the galaxy, lying 0.7 arcseconds from the nucleus as reported in the red band of the Sloan Digital Sky Survey. Its spectrum is well described by a power law with an absorption element. The X-ray luminosity is estimated to be 1.4+0.7−0.3×1040 erg/s. The source of the X-rays could be a black hole in the nucleus or a stellar mass ultraluminous X-ray source. The mass of the central black hole is estimated to be 2×105 M☉ based on the spiral pitch angle and 7×104 M☉ based on the stellar mass.

Nearby galaxies NGC 4197 is a member of the NGC 4261 Group, also known as LGG 278. Other members of the group include NGC 4180, NGC 4215, NGC 4241, NGC 4260, NGC 4261, NGC 4233, and NGC 4234. Makarov et al considers LGG 281, which includes NGC 4235, NGC 4264, NGC 4268, NGC 4270, NGC 4273, NGC 4281, NGC 4292, NGC 4300, NGC 4378, and NGC 4412, to be also part of the same group.

References

External links

NGC 4197 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images NGC 4197 on SIMBAD

Illustrations

Worked examples

Example 1 — a first encounter with NGC 4197

Start with the simplest possible case. Write down what NGC 4197 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 4197 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 4197 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 4197

In research: NGC 4197 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 4197 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 4197 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1784, Discoveries by William Herschel, Intermediate spiral galaxies, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 4197 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 4197 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 4197 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 4197 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 4197 in simple terms?

Why does NGC 4197 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 4197?

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 4197.