astronomy

NGC 129

NGC 129 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 129 rather than just read about it. In short: NGC 129 is an open cluster stars in the northern constellation of Cassiopeia. It was discovered by William Herschel in 1788.

Key takeaways

NGC 129 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 129 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 129 from memory before moving on to harder problems.

Reference excerpt

NGC 129 is an open cluster stars in the northern constellation of Cassiopeia. It was discovered by William Herschel in 1788. It is located almost exactly halfway between the bright stars Caph (β Cassiopeiae) and γ Cassiopeiae. It is large but not dense and can be observed by binoculars, through which the most obvious component is a small triangle of stars of magnitude 8 and 9, located in the center of the cluster. NGC 129 contains several giant stars. The brightest member of the cluster is DL Cassiopeiae, a binary system which contains a Cepheid variable with a 8,00 day period. Using the fluctuations of the brightness of DL Cassiopeia from 8,7 to 9,28, Gieren et al. in 1994 determined the distance of NGC 129 to be 2034 ±110 pc (6.630 ±360 ly), much larger than the distance obtained by Turner et al. (1992), who obtained a distance of 1,670 ±13 pc from ZAMS fitting of the cluster. A possible cause of this difference is the different level of obstruction of light and star reddening of the stars of the cluster. One more cepheid variable, V379 Cas, is also a possible member of NGC 129.

References

External links Media related to NGC 129 at Wikimedia Commons

Illustrations

Worked examples

Example 1 — a first encounter with NGC 129

Start with the simplest possible case. Write down what NGC 129 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 129 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 129 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 129

In research: NGC 129 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 129 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 129 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1788, Cassiopeia (constellation), Discoveries by William Herschel, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 129 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 129 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 129 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 129 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 129 in simple terms?

NGC 129 is an open cluster stars in the northern constellation of Cassiopeia. It was discovered by William Herschel in 1788.

Why does NGC 129 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 129?

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 129.