astronomy

NGC 7253

NGC 7253 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 7253 rather than just read about it. In short: NGC 7253 is a pair of spiral galaxies in the constellation Pegasus. It was discovered by the German-British astronomer Albert Marth on 9 September 1863.

Key takeaways

NGC 7253 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 7253 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 7253 from memory before moving on to harder problems.

Reference excerpt

NGC 7253 is a pair of spiral galaxies in the constellation Pegasus. It was discovered by the German-British astronomer Albert Marth on 9 September 1863. It is listed in Halton Arp's Atlas of Peculiar Galaxies as Arp 278, as an example of gravitationally interacting galaxies. Of the pair, the galaxy to the north is known individually as NGC 7253A. Its velocity relative to the cosmic microwave background is 4,235 ± 24 km/s, which corresponds to a Hubble distance of 62.5 ± 4.4 Mpc (~204 million light-years). The other galaxy in the pair is known individually as NGC 7253B. Its velocity relative to the cosmic microwave background is 4,165 ± 24 km/s, which corresponds to a Hubble distance of 61.4 ± 4.3 Mpc (~200 million light-years). With a surface brightness equal to 14.06 Mag/arcsec2, NGC 7253B can be described as a low surface brightness galaxy. NGC 7253 has a possible active galactic nucleus, i.e. it has a compact region at the center of a galaxy that emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars.

Supernova One supernova has been observed in NGC 7253B: SN 2002jg (Type Ia, mag. 17) was discovered by Mike Schwartz and LOTOSS (Lick Observatory and Tenagra Observatory Supernova Searches) on 23 November 2002.

Image Gallery

See also List of NGC objects (7001–7840)

References

External links Media related to NGC 7253 at Wikimedia Commons NGC 7253 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 7253

Start with the simplest possible case. Write down what NGC 7253 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 7253 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 7253 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 7253

In research: NGC 7253 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 7253 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 7253 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Arp objects, Astronomical objects discovered in 1863, Discoveries by Albert Marth, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 7253 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.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study NGC 7253 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 7253 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 7253 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 7253 in simple terms?

NGC 7253 is a pair of spiral galaxies in the constellation Pegasus. It was discovered by the German-British astronomer Albert Marth on 9 September 1863.

Why does NGC 7253 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 7253?

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 7253.