astronomy

SU Persei

SU 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 SU Persei rather than just read about it. In short: SU Persei is a red supergiant star located in the constellation of Perseus. It is located within the Double Cluster, 7,250+470−420 light-years away.

Key takeaways

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

Reference excerpt

SU Persei is a red supergiant star located in the constellation of Perseus. It is located within the Double Cluster, 7,250+470−420 light-years away. It is a semiregular variable star that ranges in brightness from magnitude 7.2 to 8.7, which makes it too faint to be seen with the naked eye, but can be seen with binoculars or a telescope. SU Persei was imaged by the CHARA array in 2015, 2016, 2019, 2020, and 2021. Observations during 2015 and 2016 with CHARA show that the star has an angular diameter between 3.51 and 3.68 milliarcseconds. Considering its large distance from Earth, this results in a radius between 1,044 and 1,139 times that of the Sun, making it one of the largest stars known. SU Persei is losing mass at a rate of 1.62+0.72−0.63×10−6 M☉ per year, via a stellar wind. In 1907, Henrietta Swan Leavitt discovered that the star's brightness varies by examining photographic plates. It was given its variable star designation, SU Persei in 1908.

See also List of stars in Perseus List of stars with resolved images AZ Cygni

References

Illustrations

Worked examples

Example 1 — a first encounter with SU Persei

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

In research: SU 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 SU 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: SU Persei is common in secondary-school and first-year university syllabi. It links to neighbouring topics Henry Draper Catalogue objects, M-type supergiants, Objects with variable star designations, so understanding it makes those chapters shorter.
In everyday life: Look for SU 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 SU Persei in 20 minutes

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

Frequently asked questions

What is SU Persei in simple terms?

SU Persei is a red supergiant star located in the constellation of Perseus. It is located within the Double Cluster, 7,250+470−420 light-years away.

Why does SU 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 SU 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 SU Persei.