science

NGC 6231

NGC 6231 is a science 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 6231 rather than just read about it. In short: NGC 6231 (also known as Caldwell 76 or the Baby Scorpion Cluster) is an open cluster in the southern sky located half a degrees north of Zeta Scorpii. NGC 6231 is part of a swath of young, bluish stars in the constellation Scorpius known as the Scorpius OB1 association.

Key takeaways

NGC 6231 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect NGC 6231 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 6231 from memory before moving on to harder problems.

Reference excerpt

NGC 6231 (also known as Caldwell 76 or the Baby Scorpion Cluster) is an open cluster in the southern sky located half a degrees north of Zeta Scorpii. NGC 6231 is part of a swath of young, bluish stars in the constellation Scorpius known as the Scorpius OB1 association. The star Zeta1 (HR 6262) is a member of this association, while its brighter apparent partner, Zeta2 (HR 6271), is only 150 ly from Earth and so is not a member. This cluster is estimated to be about 2–7 million years old, and is approaching the Solar System at 22 km/s. The cluster and association lie in the neighboring Sagittarius Arm of the Milky Way. Zeta1 Scorpii (spectral type O8 and magnitude 4.71.) is the brightest star in the association, and one of the most radiant stars known in the galaxy. NGC 6231 was used to measure the binary fraction of B-type stars: 52%±8%, indicating that B-type stars are commonly found in binary systems, but not as commonly as in O-type stars. NGC 6231 also includes three Wolf-Rayet stars: HD 151932, HD 152270, and HD 152408.

Discovery The cluster was discovered by Giovanni Batista Hodierna before 1654. Hodierna listed it as Luminosae in his catalogue of deep sky observations. This catalogue was included in his book De Admirandis Coeli Characteribuse published in 1654 at Palermo. It was independently observed by other astronomers after Hodierna, including Edmond Halley (1678), Jean-Philippe de Cheseaux (1745–46), and Abbe Lacaille (1751–52).

Common names The cluster forms the head of the False Comet, a wider collection of stars from Scorpius OB1 running northward from Zeta Scorpii and NGC 6231 roughly halfway toward Mu Scorpii. The tail is formed by two clusters, Collinder 316 and Trumpler 24. Trumpler 24 is surrounded by the emission nebula IC 4628, also known as the Prawn Nebula, where the tail appears to fan out. The cluster is also sometimes known as The Northern Jewel Box, due to its similar appearance to the NGC 4755, the Jewel Box cluster, which is further south in the sky.

Chinese astronomy In Chinese astronomy, NGC 6231 is usually identified as Shengong (Chinese: 神宮; pinyin: Shéngōng), a dressing room. In older sources, Shengong corresponds to the star Mu2 Scorpii, or another faint star or patch of stars nearby; the name has been adopted by the IAU Working Group on Star Names for the star HD 153072. Still other sources identify Shengong as Zeta Scorpii.

Gallery

Notes

External links

SEDS NGC 6231 at DOCdb (Deep Sky Observer's Companion)

NGC 6231 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 6231

Start with the simplest possible case. Write down what NGC 6231 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 6231 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 6231 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 6231

In research: NGC 6231 appears in science 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 6231 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 6231 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Caldwell objects, NGC objects, Open clusters, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 6231 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 6231 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 6231 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 6231 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 6231 in simple terms?

Why does NGC 6231 matter?

Because it connects several science 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 6231?

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 6231.