astronomy

NGC 5668

NGC 5668 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 5668 rather than just read about it. In short: NGC 5668 is a nearly face-on spiral galaxy, visual magnitude about 11.5, located about 81 million light years away in the constellation Virgo. It was discovered on 29 April 1786 by William Herschel.

Key takeaways

NGC 5668 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 5668 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 5668 from memory before moving on to harder problems.

Reference excerpt

NGC 5668 is a nearly face-on spiral galaxy, visual magnitude about 11.5, located about 81 million light years away in the constellation Virgo. It was discovered on 29 April 1786 by William Herschel. NGC 5668 is a member of the NGC 5638 Group of galaxies, itself one of the Virgo III Groups strung out to the east of the Virgo Supercluster of galaxies. In addition, A.M. Garcia listed NGC 5668 in the 31 member NGC 5746 galaxy group (also known as LGG 386). As seen from the Earth, it is inclined by an angle of 18° to the line of sight along a position angle of 145°. The morphological classification in the De Vaucouleurs system is SA(s)d, indicating a pure spiral structure with loosely wound arms. However, optical images of the galaxy indicate the presence of a weak bar structure spanning an angle of 12″ across the nucleus. There is a dwarf galaxy located around 650×10^3 ly (200 kpc) to the southeast of NGC 5668, and the two may be gravitationally interacting.

Supernovae Three supernovae have been observed in this galaxy:

SN 1952G (type unknown, mag. 17.9) was discovered by Fritz Zwicky on 18 April 1952. SN 1954B (Type Ia, mag. 12.3) was discovered by Paul Wild on 4 May 1954. SN 2004G (Type II, mag. 17.2) was discovered by Reiki Kushida on 19 January 2004. It was initially imaged at 43" to the west and 12".5 south of the galaxy core. High-velocity clouds of neutral hydrogen have been observed in NGC 5668, which may have their origin in supernova explosions and strong stellar winds.

Gallery

See also List of NGC objects (5001–6000)

Notes

References

External links Media related to NGC 5668 at Wikimedia Commons

Illustrations

Worked examples

Example 1 — a first encounter with NGC 5668

Start with the simplest possible case. Write down what NGC 5668 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 5668 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 5668 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 5668

In research: NGC 5668 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 5668 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 5668 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1786, Discoveries by William Herschel, IRAS catalogue objects, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 5668 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 5668 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 5668 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 5668 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 5668 in simple terms?

NGC 5668 is a nearly face-on spiral galaxy, visual magnitude about 11.5, located about 81 million light years away in the constellation Virgo. It was discovered on 29 April 1786 by William Herschel.

Why does NGC 5668 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 5668?

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 5668.