astronomy

NGC 3656

NGC 3656 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 3656 rather than just read about it. In short: NGC 3656 is a peculiar galaxy formed by the collision of two galaxies in the constellation of Ursa Major. It is located about 135 million light years away from Earth, which means, given its apparent dimensions, that NGC 3656 is approximately 70,000 light years across.

Key takeaways

NGC 3656 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 3656 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 3656 from memory before moving on to harder problems.

Reference excerpt

NGC 3656 is a peculiar galaxy formed by the collision of two galaxies in the constellation of Ursa Major. It is located about 135 million light years away from Earth, which means, given its apparent dimensions, that NGC 3656 is approximately 70,000 light years across. It was discovered by William Herschel on April 14, 1789.

Characteristics NGC 3656 is a galaxy merger, created by the collision of two disk galaxies. The merger has created shells around the galaxy and two faint tidal tails. The first tail emanates from a position angle of 260° and after bends to the north-northwest. Its total extent is about 180 arcseconds, towards a dwarf galaxy, and maybe even more, towards a second dwarf galaxy. Its width is 15 arcseconds. The other tail lies at the north-northeast part of the galaxy and is not as well defined as the other. Other characteristics of the galaxy include the presence of a condensation at the south part of the galaxy connected with the rest of the galaxy with a ring-like feature and is associated with a bright shell. A prominent feature of the galaxy is a dark lane running across the minor axis of the galaxy, similar to that observed in Centaurus A. At the centre of the galaxy a warped molecular gas disk extending for about 7 kiloparsecs has been observed in H I imaging, with an estimated mass of 2×109 M☉. The inner part of the disk features more intense star formation. The total star formation rate of the galaxy is estimated to be 1.1 M☉ per year. The nucleus of NGC 3656 has been found to rotate around an axis that is almost perpendicular to the rotation axis of the rest of the galaxy, which is another indication of a galaxy merger.

Supernovae Two supernovae have been observed in NGC 3656:

SN 1963K (type unknown, mag. 15) was discovered by Charles Bertaud on 15 June 1963. SN 1973C (type unknown, mag. 17) was discovered by Charles Kowal on 11 January 1973. It was co-discovered by Shakhbazyan.

Nearby galaxies NGC 3656 is the foremost member in a galaxy group known as the NGC 3656 group. Another member is UGC 6422. A bit further away lies the galaxy NGC 3549 with its group. Five dwarf galaxies with estimated masses between 2×108 and 2×109 M☉ have been detected in HI imaging around the galaxy and are probably in the process of being accreted by NGC 3656.

See also List of NGC objects (3001–4000)

References

External links

NGC 3656 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images NGC 3656 on SIMBAD

Illustrations

Worked examples

Example 1 — a first encounter with NGC 3656

Start with the simplest possible case. Write down what NGC 3656 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 3656 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 3656 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 3656

In research: NGC 3656 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 3656 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 3656 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Arp objects, Astronomical objects discovered in 1789, Discoveries by William Herschel, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 3656 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 3656 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 3656 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 3656 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 3656 in simple terms?

Why does NGC 3656 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 3656?

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 3656.