astronomy

NGC 7678

NGC 7678 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 7678 rather than just read about it. In short: NGC 7678 is an intermediate spiral galaxy located in the constellation Pegasus. It is located at a distance of about 130 million light years from Earth, which, given its apparent dimensions, means that NGC 7678 is about 95,000 light years across.

Key takeaways

NGC 7678 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 7678 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 7678 from memory before moving on to harder problems.

Reference excerpt

NGC 7678 is an intermediate spiral galaxy located in the constellation Pegasus. It is located at a distance of about 130 million light years from Earth, which, given its apparent dimensions, means that NGC 7678 is about 95,000 light years across. It was discovered by William Herschel on September 15, 1784.

Characteristics NGC 7678 is a grand design spiral galaxy with two arms, from which the south arm is more prominent, and as a result the galaxy is asymmetrical. It was initially considered to that the asymmetry was the caused by a different galaxy interacting with NGC 7678 but further observations reveal that this is not the case. The galaxy is featured in Arp's Atlas of Peculiar Galaxies as number 28, in the category "One heavy arm". The galaxy has a small nucleus and a weak bar. The galaxy had been identified based on the spectral emission as a type 2 Seyfert galaxy, but the ratio of [NII]λ 6583/H-alpha indicates it is an HII region or a low-ionization nuclear emission-line region, with the HII region classification being supported by the λ6584/Hα and λ5007/Hβ ratios. Many large HII regions are visible at the southern arm. Ten giant HII regions have been detected in NGC 7678, with the largest having a mass of 107 M☉. These regions are places of active star formation and contain star clusters. The largest HII region in the southern arm could be the relic of a satellite galaxy that merged with NGC 7678 and caused the starburst activity. The total star formation rate of the galaxy is estimated to be 3.8 M☉ per year based on corrected Paα emission or 7.4 M☉ per year based on infrared emission.

Nearby galaxies NGC 7678 is an isolated galaxy in the kiloparsec scale. A. M. Garcia listed the galaxy as the namesake of the NGC 7678 galaxy group (also known as LGG 474). Other members of the group include NGC 7673, NGC 7677, and NGC 7664.

Supernovae Four supernovae have been observed in NGC 7678:

SN 1997dc (Type Ib, mag. 18.3) was discovered by the BAO Supernova Survey on 5 August 1997. SN 2002dp (Type Ia, mag. 15.1) was discovered by Alain Klotz on 18 June 2002. SN 2009ga (Type II-P, mag. 16.2) was discovered by Kōichi Itagaki on 9 June 2009. SN 2021qvr (Type II, mag. 17.707) was discovered by ATLAS on 22 June 2021.

See also List of NGC objects (7001–7840)

References

External links

NGC 7678 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images NGC 7678 on SIMBAD

Illustrations

Worked examples

Example 1 — a first encounter with NGC 7678

Start with the simplest possible case. Write down what NGC 7678 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 7678 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 7678 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 7678

In research: NGC 7678 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 7678 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 7678 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Arp objects, Astronomical objects discovered in 1784, Discoveries by William Herschel, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 7678 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 7678 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 7678 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 7678 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 7678 in simple terms?

Why does NGC 7678 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 7678?

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 7678.