astronomy

NGC 5161

NGC 5161 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 5161 rather than just read about it. In short: NGC 5161 is a spiral galaxy in the constellation Centaurus. Its velocity with respect to the cosmic microwave background is 2,668±20 km/s, which corresponds to a Hubble distance of 128.4 ± 9.0 Mly (39.36 ± 2.77 Mpc).

Key takeaways

NGC 5161 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 5161 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 5161 from memory before moving on to harder problems.

Reference excerpt

NGC 5161 is a spiral galaxy in the constellation Centaurus. Its velocity with respect to the cosmic microwave background is 2,668±20 km/s, which corresponds to a Hubble distance of 128.4 ± 9.0 Mly (39.36 ± 2.77 Mpc). However, 28 non-redshift measurements give a much closer mean distance of 74.15 ± 2.53 Mly (22.736 ± 0.777 Mpc). It was discovered by British astronomer John Herschel on 3 June 1836.

Characteristics The plane of the galactic disk is inclined at an angle of 68° to the line of sight from the Earth. The galaxy has a faint bar which near its ends, were the spiral arms begin, has ansae. The galaxy has two spiral arms which can be followed for more than 180 degrees. The arms are patchy and fragmented and feature small star forming areas visible in H alpha. There is also H alpha emission from the nucleus. In near infrared the bulge appears more pronounced and the outer arms have low surface brightness. The stellar mass of the galaxy is estimated to be 1010.5 M☉. In the centre of the galaxy is predicted to lie a supermassive black hole whose mass is estimated to be between 1.2 and 7.2 million solar masses, based on the spiral arm pitch angle.

Supernovae Two supernovae have been observed in NGC 5161:

SN 1974B (type unknown, mag. 14.5) was discovered by Charles Kowal on 28 January 1974. SN 1998E (Type IIn, mag. 16.5) was discovered by the Perth Astronomical Research Group on 29 January 1998.

Nearby galaxies NGC 5161 belongs to the NGC 5188 group. Other members of the group include NGC 5188, ESO 382-066, and ESO 383-035.

See also New General Catalogue List of NGC objects (5001–6000)

References

External links Media related to NGC 5161 at Wikimedia Commons detailed information on NGC 5161

NGC 5161 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 5161

Start with the simplest possible case. Write down what NGC 5161 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 5161 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 5161 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 5161

In research: NGC 5161 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 5161 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 5161 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1836, Centaurus, Discoveries by John Herschel, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 5161 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 5161 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 5161 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 5161 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 5161 in simple terms?

Why does NGC 5161 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 5161?

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 5161.