astronomy

NGC 1261

NGC 1261 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 1261 rather than just read about it. In short: NGC 1261 (also known as Caldwell 87) is a globular cluster of stars in the southern constellation of Horologium, first discovered by Scottish astronomer James Dunlop in 1826. The cluster is located at a distance of 53 kilolight-years from the Sun, and 59 kilolight-years from the Galactic Center.

Key takeaways

NGC 1261 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 1261 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 1261 from memory before moving on to harder problems.

Reference excerpt

NGC 1261 (also known as Caldwell 87) is a globular cluster of stars in the southern constellation of Horologium, first discovered by Scottish astronomer James Dunlop in 1826. The cluster is located at a distance of 53 kilolight-years from the Sun, and 59 kilolight-years from the Galactic Center. It is about 10.24 billion years old with 341,000 times the mass of the Sun. The cluster does not display the normal indications of core collapse, but evidence suggests it may have instead passed through a post core-collapse bounce state within the past two billion years. The central luminosity density is 2.22 L☉·pc−3, which is low for a globular cluster. Despite this, it has a Shapley–Sawyer Concentration Class of II, indicating a dense central concentration. A total of 22 RR Lyrae variables have been discovered in this cluster, along with two long-period variables, three SX Phoenicis variables, and an eclipsing binary. It was determined to be an Oosterhoff type I cluster, based on the periods of fourteen of the RR Lyrae variables. 18 probable blue straggler candidates have been identified.

References

External links Media related to NGC 1261 at Wikimedia Commons

NGC 1261 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images SEDS NASA data Photometry paper Globular Clusters Database

Illustrations

Worked examples

Example 1 — a first encounter with NGC 1261

Start with the simplest possible case. Write down what NGC 1261 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 1261 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 1261 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 1261

In research: NGC 1261 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 1261 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 1261 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1826, Caldwell objects, Globular clusters, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 1261 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 1261 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 1261 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 1261 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 1261 in simple terms?

Why does NGC 1261 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 1261?

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 1261.