astronomy

Pi Persei

Pi 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 Pi Persei rather than just read about it. In short: π Persei, Latinized as Pi Persei, is a single star in the northern constellation of Perseus. It has the traditional name Gorgonea Secunda , the second of three Gorgons in the mythology of the hero Perseus.

Key takeaways

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

Reference excerpt

π Persei, Latinized as Pi Persei, is a single star in the northern constellation of Perseus. It has the traditional name Gorgonea Secunda , the second of three Gorgons in the mythology of the hero Perseus. This star has a white hue and is faintly visible to the naked eye with an apparent visual magnitude of +4.7. It is located at a distance of approximately 303 light years from the Sun based on parallax, and is moving further away with a radial velocity of +14 km/s. This object is an A-type main-sequence star with a stellar classification of A2Vn, where the 'n' suffix indicates broad (nebulous) lines due to rapid rotation. It is spinning with a projected rotational velocity of 186 km/s, which is creating an equatorial bulge that is 6% wider than the polar radius. The star is 272 million years old with double the mass of the Sun. It has 4.8 times the Sun's radius and is radiating 170 times the luminosity of the Sun from its photosphere at an effective temperature of 9,290 K. In Chinese astronomy, this star is named Jīshī (Chinese: 積屍), meaning Heap of Corpses. R. H. Allen transliterated this name as Tseih She and wrongly identified it with Algol.

References

Illustrations

Worked examples

Example 1 — a first encounter with Pi Persei

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

In research: Pi 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 Pi 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: Pi Persei is common in secondary-school and first-year university syllabi. It links to neighbouring topics A-type main-sequence stars, Bayer objects, Bright Star Catalogue objects, so understanding it makes those chapters shorter.
In everyday life: Look for Pi 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Pi Persei” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Pi Persei in 20 minutes

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

Frequently asked questions

What is Pi Persei in simple terms?

Why does Pi 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 Pi 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 Pi Persei.