astronomy

NGC 7408

NGC 7408 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 7408 rather than just read about it. In short: NGC 7408 is a barred spiral galaxy in the constellation of Tucana. It has an apparent visual magnitude of 13.33 and an angular size of 1.5′ × 1.2′.

Key takeaways

NGC 7408 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 7408 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 7408 from memory before moving on to harder problems.

Reference excerpt

NGC 7408 is a barred spiral galaxy in the constellation of Tucana. It has an apparent visual magnitude of 13.33 and an angular size of 1.5′ × 1.2′. Its velocity with respect to the cosmic microwave background is 3,372±13 km/s, which corresponds to a Hubble distance of 162.2 ± 11.4 Mly (49.73 ± 3.49 Mpc). However, 12 non-redshift measurements give a closer mean distance of 142.80 ± 5.67 Mly (43.783 ± 1.739 Mpc). It was discovered by British astronomer John Herschel on 1 November 1834. The morphological classification of NGC 7408 is SB(s)cd, indicating a barred spiral form (SB) with no ring structure (s) and closely wound spiral arms (cd). It a Seyfert II galaxy, i.e. it has a quasar-like nucleus with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, the host galaxy is clearly detectable.

NGC 7329 group NGC 7408 is a member of the NGC 7329 group (also known as LGG 462). This group contains at least 11 galaxies, including NGC 7329, NGC 7358, NGC 7417, IC 5222, IC 5227, IC 5244, IC 5250, IC 5266, IC 5272, and ESO 109-32.

Supernovae Two supernovae have been observed in NGC 7408:

SN 2007bn (type unknown, mag. 17) was discovered by R. Martin and the Perth Observatory Automated Supernova Search on 18 April 2007. SN 2009bu (Type II-P, mag. 16.4) was discovered by Alessandro Dimai on 25 March 2009.

See also List of NGC objects (7001–7840)

References

External links NGC 7408 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 7408

Start with the simplest possible case. Write down what NGC 7408 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 7408 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 7408 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 7408

In research: NGC 7408 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 7408 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 7408 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1834, Barred spiral galaxies, Discoveries by John Herschel, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 7408 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 7408 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 7408 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 7408 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 7408 in simple terms?

NGC 7408 is a barred spiral galaxy in the constellation of Tucana. It has an apparent visual magnitude of 13.33 and an angular size of 1.5′ × 1.2′.

Why does NGC 7408 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 7408?

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 7408.