astronomy

NGC 7418

NGC 7418 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 7418 rather than just read about it. In short: NGC 7418 is an intermediate spiral galaxy located in the constellation Grus. It is located at a distance of circa 60 million light-years from Earth, which, given its apparent dimensions, means that NGC 7418 is about 60,000 light-years across.

Key takeaways

NGC 7418 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 7418 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 7418 from memory before moving on to harder problems.

Reference excerpt

NGC 7418 is an intermediate spiral galaxy located in the constellation Grus. It is located at a distance of circa 60 million light-years from Earth, which, given its apparent dimensions, means that NGC 7418 is about 60,000 light-years across. It was discovered by John Herschel on August 30, 1834.

Characteristics NGC 7418 has a bright nucleus incorporated into a bar. The bar appears strong in the infrared H-band while in the optical wavelengths it appears weaker or even unbarred. The spiral arms of the galaxy emanate from the end of the bar. The galaxy has four grand design spiral arms. Their inner parts have knots while the outermost are smooth. The galaxy is seen with an inclination of 42 degrees. In the centre of NGC 7418 is believed to lie a supermassive black hole with an estimated mass between 1 and 15 million (106.58 ± 0.59) M☉, based on the spiral pitch angle. The centre of the galaxy has also been found to host a massive stellar cluster, with an estimated mass of nearly 60 million (107.78 ± 0.19) M☉. The existence of this nuclear star cluster doesn't rule out the existence of a supermassive black hole. Galaxies like the Milky Way and the Andromeda Galaxy have been found to host both. The stellar population at the nucleus of NGC 7418 has been found to be quite young, with mean age less than 100 million years, indicating recent star forming activity.

Supernova One supernova has been observed in NGC 7418.

SN 1983 Z (type unknown, mag. 15.5) was discovered by Luis Eduardo González (astronomer) on September 3, 1983, at Cerro El Roble. The supernova was 11" west and 52" south of the nucleus of the galaxy.

Nearby galaxies NGC 7418 is a member of a galaxy group known as the IC 1459 group. It is a loose group centred at IC 1459 and contains a large number of spiral galaxies. Other members include NGC 7418A, NGC 7421, IC 5264, IC 5269, IC 5269B, IC 5270, and IC 5273. NGC 7421 lies 19.5 arcminutes away and NGC 7418A lies 16.5 arcminutes to the north as seen in the sky. This group, along with the NGC 7582 group, form the Grus cloud, a region of elevated galaxy density. The Grus cloud, along with the nearby Pavo-Indus cloud, lies between the Local Supercluster and Pavo–Indus Supercluster. The group features both diffuse X-ray emission from the intergalactic medium and HI emission. Based on the presence of both, it has been suggested that the group is in its early stages of assembling from different subgroups. Three HI clouds have been found to be associated with the group, two located near IC 5270 and one near NGC 7418, at its northwest edge, with total mass 6×108 M☉. These HI clouds are believed to have formed from gas stripped from the galaxies as a result of interactions.

References

External links

NGC 7418 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images NGC 7418 on SIMBAD

Illustrations

Worked examples

Example 1 — a first encounter with NGC 7418

Start with the simplest possible case. Write down what NGC 7418 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 7418 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 7418 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 7418

In research: NGC 7418 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 7418 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 7418 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1834, Discoveries by John Herschel, Grus (constellation), so understanding it makes those chapters shorter.
In everyday life: Look for NGC 7418 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 7418 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 7418 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 7418 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 7418 in simple terms?

Why does NGC 7418 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 7418?

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 7418.