astronomy

NGC 7217

NGC 7217 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 7217 rather than just read about it. In short: NGC 7217 is an unbarred spiral galaxy in the constellation Pegasus. Features NGC 7217 is a gas-poor system whose main features are the presence of several rings of stars concentric to its nucleus: three main ones –the outermost one being of the most prominent and the one that features most of the gas and star formation of this galaxy – plus several others inside the innermost one discovered with the help of the Hubb…

Key takeaways

NGC 7217 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 7217 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 7217 from memory before moving on to harder problems.

Reference excerpt

NGC 7217 is an unbarred spiral galaxy in the constellation Pegasus.

Features NGC 7217 is a gas-poor system whose main features are the presence of several rings of stars concentric to its nucleus: three main ones –the outermost one being of the most prominent and the one that features most of the gas and star formation of this galaxy – plus several others inside the innermost one discovered with the help of the Hubble Space Telescope; a feature that suggests NGC 7217's central regions have suffered several starbursts. There is also a very large and massive spheroid that extends beyond its disk. Other noteworthy features this galaxy has are the presence of a number of stars rotating in the opposite direction around the galaxy's center to most of them and two distinct stellar populations: one of intermediate age on its innermost regions and a younger, metal-poor version on its outermost ones. It has been suggested these features were caused by a merger with another galaxy and, in fact, computer simulations show that NGC 7217 could have been a large lenticular galaxy that merged with one or two smaller gas-rich ones of late Hubble type becoming the spiral galaxy we see today; however right now this galaxy is isolated in space, with no nearby major companions. More recent research presents a somewhat different scenario in which NGC 7217's massive bulge and halo would have been formed in a merger and the disk formed later (and is still growing) either accreting gas from the intergalactic medium or smaller gas-rich galaxies, or most likely from a previously existing reserve.

See also NGC 1512 NGC 7742, a very similar galaxy in the same constellation

References

External links

NGC 7217 Archived 2009-06-03 at the Wayback Machine http://atlas.zevallos.com.br/

NGC 7217 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images

Illustrations

Worked examples

Example 1 — a first encounter with NGC 7217

Start with the simplest possible case. Write down what NGC 7217 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 7217 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 7217 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 7217

In research: NGC 7217 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 7217 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 7217 is common in secondary-school and first-year university syllabi. It links to neighbouring topics NGC objects, Pegasus (constellation), Principal Galaxies Catalogue objects, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 7217 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 7217 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 7217 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 7217 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 7217 in simple terms?

NGC 7217 is an unbarred spiral galaxy in the constellation Pegasus. Features NGC 7217 is a gas-poor system whose main features are the presence of several rings of stars concentric to its nucleus: three main ones –the outermost one being of the most prominent and the one that features most of the g…

Why does NGC 7217 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 7217?

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 7217.