astronomy

NGC 680

NGC 680 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 680 rather than just read about it. In short: NGC 680 is an elliptical galaxy located in the constellation Aries. It is located at a distance of circa 120 million light years from Earth, which, given its apparent dimensions, means that NGC 680 is about 100,000 light years across.

Key takeaways

NGC 680 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 680 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 680 from memory before moving on to harder problems.

Reference excerpt

NGC 680 is an elliptical galaxy located in the constellation Aries. It is located at a distance of circa 120 million light years from Earth, which, given its apparent dimensions, means that NGC 680 is about 100,000 light years across. It was discovered by William Herschel on September 15, 1784.

Characteristics NGC 680 appears asymmetrical, probably due to interactions with other galaxies. The tidal forces have disturbed the shape of the galaxy and have created arcs, shells and an asymmetric envelope. It also features a patchy dusty feature. The hydrogen gas of the galaxy forms two large diffuse stellar plumes that may be associated with tidal tails. One plume extends to the south-east and the other to the north-west and have projected lengths of 75 and 60 kpc accordingly. However, the galaxy does not have a kinematically decoupled nucleus. All these characteristics indicate that the current galaxy was created by the merger of two galaxies, maybe two gas rich galaxies, maybe spirals, based on the amount of gas located around the galaxy. The lack of detection of molecular gas indicated that the merger took place 1-2 billion years ago. The merger remnant is characterised as a "fast rotator" that indicates either that the galaxy retained the angular momentum of the original galaxy or that the two galaxies merged in a way that they attained angular momentum. The mean age of the stellar population of the central 0.3 kpc of NGC 680 is 7.8 billion years, while for the central 2.6 kpc the mean age is 6.5 billion years. Ionised gas has been detected in the nucleus of the galaxy, it is probably created by the gas emitted by stars at the end of their life. An arc of bluer and younger stars has been detected east of the galaxy.

Nearby galaxies NGC 680 is a member of a galaxy group known as the NGC 691 group. Other members of the group include IC 163, NGC 678, NGC 691, NGC 694, IC 167, and NGC 697. NGC 680 forms a pair with NGC 678, located 5.5 arcminutes to the northwest, and IC 1730 lies 3.7 arcminutes northwards. Hydrogen emission surrounds both NGC 680 and the nearby NGC 678 and an HI tail has been found to extend towards NGC 691, with the total of this cloud HI mass estimated to by about 5×109 M☉. This gas was probably stripped by NGC 678 after a close encounter with NGC 680. However, with the use of deep photography, a stellar bridge between the two galaxies has not been detected, nor between NGC 680 and IC 1730.

References

External links

NGC 680 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images NGC 680 on SIMBAD

Illustrations

Worked examples

Example 1 — a first encounter with NGC 680

Start with the simplest possible case. Write down what NGC 680 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 680 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 680 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 680

In research: NGC 680 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 680 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 680 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aries (constellation), Astronomical objects discovered in 1784, Discoveries by William Herschel, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 680 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 680 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 680 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 680 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 680 in simple terms?

Why does NGC 680 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 680?

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 680.