astronomy

NGC 7679

NGC 7679 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 7679 rather than just read about it. In short: NGC 7679 is a lenticular galaxy with a peculiar morphology in the constellation Pisces. It is located at a distance of about 200 million light years from Earth, which, given its apparent dimensions, means that NGC 7679 is about 60,000 light years across.

Key takeaways

NGC 7679 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 7679 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 7679 from memory before moving on to harder problems.

Reference excerpt

NGC 7679 is a lenticular galaxy with a peculiar morphology in the constellation Pisces. It is located at a distance of about 200 million light years from Earth, which, given its apparent dimensions, means that NGC 7679 is about 60,000 light years across. It was discovered by Heinrich d'Arrest on September 23, 1864. The total infrared luminosity is 1011.05 L☉, and thus it is categorised as a luminous infrared galaxy. NGC 7679 is both a starburst galaxy and a Seyfert galaxy.

Characteristics NGC 7679 is a barred lenticular galaxy seen face on, and is noted for its distorted shape. The galaxy has two plumes in opposite directions, possibly the result of tidal interaction with NGC 7682, and smooth outer arms. The inner region is of high surface brightness with many knots and a high star formation rate. The star formation rate of the galaxy is estimated to be 80 M☉ per year based on the x-ray luminosity observed by XMM-Newton, and on the H-alpha luminosity of 21.2 ± 0.2 M☉ per year while observations in infrared indicate a star formation of 11.35 ± 0.6 M☉ per year. There is evidence of massive starburst activity in the circumnuclear region, with 35% of the stars there being aged less than 10 million years. A ring of ionised gas dominates both the optical and infrared wavelengths and is the locus of the starburst activity.

Nucleus The nucleus of NGC 7679 has been found to be active and has been categorised as a Seyfert galaxy. The most accepted theory for the energy source of Seyfert galaxies is the presence of an accretion disk around a supermassive black hole. NGC 7679 is believed to host a supermassive black hole whose mass is estimated to be 5.9×106 (106.77) M☉ based on velocity dispersion. The X-ray spectrum from BeppoSAX shows no significant absorption above 2 MeV and the iron Ka line was marginally detected. However, the galaxy shows signs of obstruction in visual light, as it lacks broad emission lines. Two possible reasons are the presence of dust or the accretion disk that produces X-rays is not obstructed but the broad line region is. The lack of X-ray absorption along with the presence of broad H-alpha lines but not broad H-beta mean that it cannot be easily categorised as a particular type of Seyfert galaxy.

Nearby galaxies NGC 7679 forms a pair with NGC 7682. NGC 7682 lies at a distance of 269.7 arcseconds, which corresponds to a projected distance of 97 kpc. The two galaxies are connected by a hydrogen bridge, a sign of a closer encounter in the past 500 million years. It is possible that the interaction of the two galaxies caused star formation in NGC 7679. A fainter galaxy has been found superimposed on the eastern arm of the galaxy, but it is actually located in the background.

See also NGC 7130 - A similar active and starburst galaxy

Gallery

References

External links Media related to NGC 7679 at Wikimedia Commons NGC 7679 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 7679

Start with the simplest possible case. Write down what NGC 7679 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 7679 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 7679 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 7679

In research: NGC 7679 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 7679 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 7679 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Arp objects, Barred lenticular galaxies, Interacting galaxies, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 7679 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 7679 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 7679 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 7679 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 7679 in simple terms?

Why does NGC 7679 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 7679?

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 7679.