astronomy

NGC 3166

NGC 3166 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 3166 rather than just read about it. In short: NGC 3166 is a lenticular galaxy in the constellation Sextans. The galaxy lies about 65 million light years away from Earth, which means, given its apparent dimensions, that NGC 3166 is approximately 105,000 light years across.

Key takeaways

NGC 3166 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 3166 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 3166 from memory before moving on to harder problems.

Reference excerpt

NGC 3166 is a lenticular galaxy in the constellation Sextans. The galaxy lies about 65 million light years away from Earth, which means, given its apparent dimensions, that NGC 3166 is approximately 105,000 light years across. It was discovered by William Herschel on December 19, 1783.

Characteristics NGC 3166 has a bright, elongated nucleus, surrounded by an elliptical bright bulge, elongated along a nearly east-west axis. In the central 6-7 arcseconds there is evidence of a circumnuclear star disk. The age of the stars in the nucleus is estimated to be no older than two billion years. A low-surface-brightness bar is visible lying nearly perpendicular to that. The fainter parts of the bulge are nearly circular, about one arcminute in diameter, and with spiral whorls. Beyond that lies a low-surface-brightness disk, without spiral arms or knots. Dust lanes are visible over the disk of the galaxy. The stars in the disk have sub-solar metallicity, indicating the stars are more than 8 billion years old there. In ultraviolet the galaxy is asymmetric, with stronger emission west of the nucleus. That region, at the western tidal arm, is the only in the galaxy that has a spectrum similar to an HII region and is indicative of the presence of young stars. There is hydrogen emission east of the nucleus. This asymmetry could be the result of recent gas accretion, and a complete star formation ring hasn't yet formed. The current star formation rate of the galaxy is estimated to be 0.06±0.01 M☉ per year. An arm is visible in H-alpha 100 arcseconds west of the nucleus. The outer regions of the galaxy appear lopsided.

Supernova One supernova has been detected in NGC 3166. SN 2012cw (Type Ic, mag. 16.5) was discovered by Kōichi Itagaki on 14 June 2012. Its progenitor couldn't be detected in archive images by Hubble Space Telescope, indicating it had an absolute magnitude of less than -7.

Nearby galaxies NGC 3166 forms an interacting pair with NGC 3169, which lies at a separation of 7.5 arcminutes. Another companion galaxy, NGC 3165, lies 4.5 arcminutes to the southwest. A tidal tail connecting NGC 3166 with NGC 3169 extending south of the galaxy is visible in radiowaves, in the hydrogen line. The total mass of hydrogen in the tail is estimated to be 108 M☉. At the end of the tail a tidal dwarf galaxy, AGC 208457, has formed. Some other gas clumps have also been detected. Three of them are classical dwarf irregular galaxies. There is extended hydrogen emission surrounding the group. These galaxies, along with NGC 3156, form the NGC 3169 Group, which is part of the Leo II Groups, a large cloud of galaxies in the Virgo Supercluster.

References

External links

NGC 3166 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images

Illustrations

Worked examples

Example 1 — a first encounter with NGC 3166

Start with the simplest possible case. Write down what NGC 3166 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 3166 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 3166 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 3166

In research: NGC 3166 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 3166 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 3166 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1783, Discoveries by William Herschel, Interacting galaxies, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 3166 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 3166 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 3166 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 3166 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 3166 in simple terms?

Why does NGC 3166 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 3166?

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 3166.