astronomy

NGC 6745

NGC 6745 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 6745 rather than just read about it. In short: NGC 6745 (also known as UGC 11391) is an irregular galaxy about 206 million light-years (63.5 mega-parsecs) away in the constellation Lyra. It was discovered by French astronomer Édouard Stephan on 24 July 1879.

Key takeaways

NGC 6745 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 6745 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 6745 from memory before moving on to harder problems.

Reference excerpt

NGC 6745 (also known as UGC 11391) is an irregular galaxy about 206 million light-years (63.5 mega-parsecs) away in the constellation Lyra. It was discovered by French astronomer Édouard Stephan on 24 July 1879. NGC 6745 is actually a trio of galaxies in the process of colliding. The three galaxies have been colliding for hundreds of millions of years. After passing through the larger galaxy (NGC 6745A), the smaller one (NGC 6745B) is now moving away. The larger galaxy was probably a spiral galaxy before the collision, but was damaged and now appears peculiar. It is unlikely that any stars in the two galaxies collided directly because of the vast distances between them. The gas, dust, and ambient magnetic fields of the galaxies, however, do interact directly in a collision. As a result of this interaction, the smaller galaxy has probably lost most of its interstellar medium to the larger one.

Supernovae Four supernovae have been observed in NGC 6745:

SN 1999bx (Type II, mag. 16.5) was discovered by the Lick Observatory Supernova Search (LOSS) on 26 April 1999. SN 2022prr (Type IIn, mag. 17.3) was discovered by ASAS-SN on 27 July 2022. SN 2023ucy (Type II, mag. 17.9) was discovered by the Zwicky Transient Facility on 5 October 2023. SN 2024ljc (Type IIb, mag. 18.736) was discovered by the Zwicky Transient Facility on 15 June 2024.

See also IC 1296 Antennae Galaxies List of NGC objects (6001–7000)

References

External links Media related to NGC 6745 at Wikimedia Commons NGC 6745: The Astronomer's Story HubbleSite - NewsCenter - A Bird's Eye view of a Galaxy Collision NASA Astronomy Picture of the Day: A Galaxy Collision in NGC 6745 (2 November 2000)

Illustrations

Worked examples

Example 1 — a first encounter with NGC 6745

Start with the simplest possible case. Write down what NGC 6745 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 6745 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 6745 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 6745

In research: NGC 6745 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 6745 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 6745 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1879, Discoveries by Édouard Stephan, Interacting galaxies, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 6745 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 6745 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 6745 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 6745 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 6745 in simple terms?

Why does NGC 6745 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 6745?

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 6745.