astronomy

NGC 7723

NGC 7723 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 7723 rather than just read about it. In short: NGC 7723 is a barred spiral galaxy located in the constellation Aquarius. It is located at a distance of about 90 million light years from Earth, which, given its apparent dimensions, means that NGC 7723 is about 95,000 light years across.

Key takeaways

NGC 7723 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 7723 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 7723 from memory before moving on to harder problems.

Reference excerpt

NGC 7723 is a barred spiral galaxy located in the constellation Aquarius. It is located at a distance of about 90 million light years from Earth, which, given its apparent dimensions, means that NGC 7723 is about 95,000 light years across. It was discovered by William Herschel on November 27, 1785. The galaxy is included in the Herschel 400 Catalogue. It lies 1.5 degrees north-northwest from Omega1 Aquarii. It can be seen with a 4-inch telescope under dark skies.

Characteristics NGC 7723 is a barred spiral galaxy. It has a bright nucleus and a boxy bulge. In the centre of the galaxy lies a supermassive black hole whose mass is estimated to be (10.6±4.9)×106 M☉ based on the spiral arm pitch angle. The bar emerges from the opposite sides of the bulge. Straight dust lanes are observed along the bar, the one smooth and the other appearing broken. The bar has a maximum apparent length of 64 arcseconds. At the end of the bar the spiral arms form a pseudoring with diameter of 71 arcseconds. Based on observations in far ultraviolet (FUV) and Hα there is active star formation at the pseudoring. Based on the B-I color profile of the galaxy the bar finishes at 23 arcseconds, at the same distance where there is a population of older stars, and thus is suggested to be the corotation radius of NGC 7723. The structure of the arms is complex. The arm that emanates from the southwest part of the bar is well defined for a quarter of a revolution and after that it becomes more diffuse and fades after reaching half a revolution. The other arm emanates from a feature about 60 degrees northwest of the bar and brightens after passing the end of the bar, and then it splits in two. The inner part forms the southwest part of the pseudoring and bifurcates after winding for about 120 degrees after the bar end, with the inner part being the brightest. The other arm becomes diffuse and of low surface brightness.

Supernova One supernova has been observed in NGC 7723: SN 1975N (Type Ia, mag. 15) was discovered by Paul Wild on 24 October 1975. It was also independently discovered by Valentin A. Lipovetsky on 27 October 1975.

Nearby galaxies NGC 7723 belongs to a small groups of galaxies known as the NGC 7727 group. Other members of the group include NGC 7727 and NGC 7724. NGC 7727 lies about 40' northwest of NGC 7723.

References

External links

NGC 7723 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 7723

Start with the simplest possible case. Write down what NGC 7723 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 7723 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 7723 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 7723

In research: NGC 7723 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 7723 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 7723 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aquarius (constellation), Astronomical objects discovered in 1785, Barred spiral galaxies, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 7723 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 7723 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 7723 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 7723 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 7723 in simple terms?

Why does NGC 7723 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 7723?

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 7723.