astronomy

NGC 45

NGC 45 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 45 rather than just read about it. In short: NGC 45 is a low surface brightness spiral galaxy in the equatorial constellation of Cetus. It was discovered by the English astronomer John Herschel on 11 November 1835.

Key takeaways

NGC 45 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 45 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 45 from memory before moving on to harder problems.

Reference excerpt

NGC 45 is a low surface brightness spiral galaxy in the equatorial constellation of Cetus. It was discovered by the English astronomer John Herschel on 11 November 1835. The galaxy is located at a distance of 22 million light years and is receding with a heliocentric radial velocity of 466 km/s. It is located in the vicinity of the Sculptor Group, but is most likely a background galaxy. The morphological class of NGC 45 is SA(s)dm, indicating this is a spiral galaxy with no prominent inner bar (SA) or ring (s) feature. There is no central bulge to speak of. The galactic plane is inclined at an angle of 55°±5° to the line of sight from the Earth, with the major axis of the elliptical profile being aligned along a position angle of 145°±5°. Star formation is proceeding at a modest rate of ~0.20 M☉·yr−1. Unlike the Milky Way, NGC 45 has no clearly defined spiral arms, and its center bar nucleus is also very small and distorted. NGC 45 thus does not have a galactic habitable zone. For the Milky Way, the galactic habitable zone is commonly believed to be an annulus with an outer radius of about 10 kiloparsecs and an inner radius close to the Galactic Center, both of which lack hard boundaries.

Astronomical Transients

Two astronomical transients have been observed in NGC 45.

AT 2018bwo (type LRN, mag. 16.4352) was discovered by the Distance Less Than 40 Mpc Survey (DLT40) on 22 May 2018. Luminous red novae are thought to be the result of stars merging. The progenitor of AT 2018bwo was a yellow supergiant star. AT 2018htr (type LBV, mag. 17.4692) was discovered by DLT40 on 3 November 2018.

Gallery

Illustrations

Worked examples

Example 1 — a first encounter with NGC 45

Start with the simplest possible case. Write down what NGC 45 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 45 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 45 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 45

In research: NGC 45 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 45 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 45 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1835, Cetus (constellation), Discoveries by John Herschel, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 45 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 45 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 45 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 45 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 45 in simple terms?

NGC 45 is a low surface brightness spiral galaxy in the equatorial constellation of Cetus. It was discovered by the English astronomer John Herschel on 11 November 1835.

Why does NGC 45 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 45?

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 45.