astronomy

V520 Persei

V520 Persei 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 V520 Persei rather than just read about it. In short: V520 Persei is a blue supergiant member of NGC 869, one of the Perseus Double Cluster open clusters. It is an irregular variable star.

Key takeaways

V520 Persei belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect V520 Persei to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of V520 Persei from memory before moving on to harder problems.

Reference excerpt

V520 Persei is a blue supergiant member of NGC 869, one of the Perseus Double Cluster open clusters. It is an irregular variable star. At a magnitude of about 6.6, V520 Persei is the brightest member in either NGC 869 or NGC 884, although the brighter HD 13994 lies in the foreground along the same line of sight.

The Washington Double Star Catalog lists V520 Per as a double star about 15" from a 13th magnitude A0 companion which is another cluster member. There are dozens of other stars within an arc-minute, including several brighter than 10th magnitude and two 15th magnitude stars closer than the listed companion. The Catalogue of Components of Double and Multiple Stars also lists a single companion, but it is an 11th magnitude star 29" away. V520 Per is a well-defined member of NGC 869 by location, proper motion, photometry, and spectroscopy, which places it at the same distance of around 7,000 light years. This is supported by the Gaia Data Release 3 parallax of 0.43 mas.

The type of variability is listed in the General Catalogue of Variable Stars as IA, indicating it is poorly studied with no clear period. The visual range is 6.52 - 6.67. Statistical analysis of Hipparcos photometry suggests a possible period of 1.6 days, but the type variability is not clearly defined. V520 Persei is a supergiant with a spectral class of B3. It also shows some emission lines in its spectrum. It has exhausted its core hydrogen and expanded into a more luminous star fusing hydrogen in a shell or helium in its core. It is over 100,000 times more luminous than the sun, although only thirty times its mass. Much of the luminosity arises from ultraviolet radiation created by the temperature of over 20,000 K. V520 Per has been identified as one of Flamsteed's "missing stars", catalogue numbers created by Flamsteed but not actually associated with a current star in that constellation. It is described as being 61 Andromedae, although it is well outside the boundary of Andromeda and Flamsteed catalogued other nearby stars in Perseus, for example 7 Persei for χ Per itself.

References

Illustrations

Worked examples

Example 1 — a first encounter with V520 Persei

Start with the simplest possible case. Write down what V520 Persei 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 V520 Persei 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 V520 Persei 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 V520 Persei

In research: V520 Persei 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 V520 Persei 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: V520 Persei is common in secondary-school and first-year university syllabi. It links to neighbouring topics B-type supergiants, Be stars, Double stars, so understanding it makes those chapters shorter.
In everyday life: Look for V520 Persei 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 V520 Persei in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what V520 Persei 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 V520 Persei out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is V520 Persei in simple terms?

V520 Persei is a blue supergiant member of NGC 869, one of the Perseus Double Cluster open clusters. It is an irregular variable star.

Why does V520 Persei 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 V520 Persei?

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 V520 Persei.