astronomy

NGC 4666

NGC 4666 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 4666 rather than just read about it. In short: NGC 4666 is a spiral galaxy in the equatorial constellation of Virgo, located at a distance of approximately 55 megalight-years from the Milky Way. It was discovered by the German-born astronomer William Herschel on February 22, 1784.

Key takeaways

NGC 4666 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 4666 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 4666 from memory before moving on to harder problems.

Reference excerpt

NGC 4666 is a spiral galaxy in the equatorial constellation of Virgo, located at a distance of approximately 55 megalight-years from the Milky Way. It was discovered by the German-born astronomer William Herschel on February 22, 1784. It is a member of the Virgo II Groups, a series of galaxies and galaxy clusters strung out from the southern edge of the Virgo Supercluster. John L. E. Dreyer described it as "bright, very large, much extended 45°±, pretty suddenly brighter middle". It is a member of an interacting system with NGC 4668 and a dwarf galaxy, and belongs to a small group that also includes NGC 4632, that is known as the NGC 4666 Group.

The morphological classification of this galaxy is SABc, which indicates a weak bar around the nucleus with moderately wound spiral arms. Viewed nearly edge-on, its galactic plane is inclined at an angle of 85°±2° to the line of sight from the Earth, with the major axis aligned along a position angle of 40°. There is an active galactic nucleus that shows a modest level of activity and is most likely heavily obscured by gas and dust. The central point source has been detected in the radio and X-ray bands. This is a starburst galaxy that is noteworthy for its vigorous star formation, which creates an unusual superwind of out-flowing gas. This wind is not visible at optical wavelengths, but is prominent in X-rays, and has been observed by the ESA XMM-Newton space telescope. The estimated star formation rate is 7.3 M☉ yr–1, with a density of 8.9×10−3 M☉ yr−1 kpc−2. Unlike in many other starburst galaxies, the star formation is spread across the disk rather than being more concentrated.

Supernovae Three supernovae have been observed in NGC 4666:

SN 1965H (Type IIP, mag. 14) was discovered by Enrique Chavira on 23 May 1965. ASASSN-14lp (Type Ia, mag. 14.3) was discovered by ASAS-SN on 9 December 2014; it was located 12″ from the center of the galaxy. SN 2019yvr (Type Ib, mag. 15.882) was discovered by ATLAS on 27 December 2019. It has a 0.005 redshift. Images of the location of the supernova before the explosion showed the progenitor star was ~19M☉.

See also List of NGC objects (4001–5000)

References

External links

SEDS: NGC 4666 The Superwind Galaxy NGC 4666, ESO Press Release.

Illustrations

Worked examples

Example 1 — a first encounter with NGC 4666

Start with the simplest possible case. Write down what NGC 4666 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 4666 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 4666 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 4666

In research: NGC 4666 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 4666 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 4666 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Barred spiral galaxies, IRAS catalogue objects, MCG objects, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 4666 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 4666 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 4666 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 4666 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 4666 in simple terms?

Why does NGC 4666 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 4666?

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 4666.