astronomy

NGC 3938

NGC 3938 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 3938 rather than just read about it. In short: NGC 3938 is an unbarred spiral galaxy in the Ursa Major constellation. It was discovered by German-British astronomer William Herschel on 6 February 1788.

Key takeaways

NGC 3938 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 3938 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 3938 from memory before moving on to harder problems.

Reference excerpt

NGC 3938 is an unbarred spiral galaxy in the Ursa Major constellation. It was discovered by German-British astronomer William Herschel on 6 February 1788. It is one of the brightest spiral galaxies in the Ursa Major South galaxy group and is roughly 76,000 light years in diameter. It is approximately 41.4 million light years away from Earth. NGC 3938 is classified as type Sc under the Hubble sequence, a loosely wound spiral galaxy with a smaller and dimmer bulge. The spiral arms of the galaxy contain many areas of ionized atomic hydrogen gas, more so towards the center. NGC 3938 is a member of the NGC 4111 Group, which is part of the Ursa Major Cloud and is the second largest group in the cloud after the NGC 3992 Group.

Supernovae and Luminous Red Nova

Five supernovae have been identified within NGC 3938:

SN 1961U (Type II, mag. 13.7) was discovered by Paul Wild on 28 December 1961. SN 1964L (Type Ic, mag. 13.3) was discovered by Paul Wild on 11 December 1964. SN 2005ay (Type II, mag. 15.6) was discovered by Doug Rich on 27 March 2005. SN 2017ein (Type Ic, mag. 17.6) was discovered by Ron Arbour on 25 May 2017 and peaked at magnitude 14.9. Images taken before the explosion point to a progenitor mass between ~47-48M☉, if it was in a single star system, and ~60-80M☉, if it was in a binary star system. SN 2022xlp (Type Ia, mag. 17) was discovered by Kōichi Itagaki on 13 October 2022. One luminous red nova has been observed in NGC 3938:

AT 2022ckk (type LRN, mag. 19.6766) was discovered by the Automatic Learning for the Rapid Classification of Events (ALeRCE) on 13 February 2022.

Gallery

See also List of NGC objects (3001–4000)

Notes

References

External links Media related to NGC 3938 at Wikimedia Commons

Illustrations

Worked examples

Example 1 — a first encounter with NGC 3938

Start with the simplest possible case. Write down what NGC 3938 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 3938 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 3938 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 3938

In research: NGC 3938 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 3938 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 3938 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1788, Discoveries by William Herschel, IRAS catalogue objects, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 3938 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 3938 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 3938 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 3938 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 3938 in simple terms?

NGC 3938 is an unbarred spiral galaxy in the Ursa Major constellation. It was discovered by German-British astronomer William Herschel on 6 February 1788.

Why does NGC 3938 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 3938?

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 3938.