astronomy

KS Persei

KS 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 KS Persei rather than just read about it. In short: KS Persei is a binary system in the equatorial constellation of Perseus. It is sometimes known as Bidelman's Star, named after William P.

Key takeaways

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

Reference excerpt

KS Persei is a binary system in the equatorial constellation of Perseus. It is sometimes known as Bidelman's Star, named after William P. Bidelman. The star is invisible to the naked eye with a mean apparent visual magnitude of 7.70. As of 2018, the structure and evolutionary history of this system remain uncertain, although some form of mass transfer is likely to have occurred to explain the observed properties. The peculiar nature of the spectra for this star was noted in the Henry Draper Catalogue and was the subject of a study by W. P. Bidelman published in 1950. He found extremely weak lines of hydrogen, similar to those for Upsilon Sagittarii but at a lower temperature. The data strongly suggested the star has an abnormally low abundance of hydrogen in the stellar atmosphere. Bidelman noted that the radial velocity of the star is variable, demonstrating that it has an unseen companion. Preliminary orbital elements for this single-lined spectroscopic binary were published in 1955 by J. F. Heard and O. Boshko, giving an orbital period of 359.7 days and with eccentricity of 0.27. They found a large mass function of 4.5, suggesting that the supergiant has lost mass and the companion is relatively massive. The mass function was revised to 3.6±0.4 in 1988, suggesting the secondary is five times more massive than the primary. Although the Gaia parallax is small (and the Hipparcos parallax is negative), KS Persei is thought to be less than 1,000 pc away. Older studies have suggested distances up to 3,900 pc. An analysis by G. Wallerstein and associates in 1967 showed that nitrogen is the second most abundant element in the primary, likely as a result of carbon cycling. G. A. Bakos attempted to photometrically detect an eclipse but was unsuccessful. However, he did tentatively detect semiregular variation with a period of ~30 days and an amplitude of 0.1 magnitude. This variability was confirmed by K. Morrison and G. P. H. Willingale in 1987, and they discovered an additional five day cycle. In 1982, J. S. Drilling and D. Schönberner detected a hot companion from spectra collected by the International Ultraviolet Explorer. The system is an infrared source, and models of the infrared flux suggest it is being emitted by circumstellar dust heated to 1,100 K. It is possible that the companion is obscured by dust.

References

Illustrations

Worked examples

Example 1 — a first encounter with KS Persei

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

In research: KS 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 KS 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: KS Persei is common in secondary-school and first-year university syllabi. It links to neighbouring topics A-type supergiants, Chemically peculiar stars, Durchmusterung objects, so understanding it makes those chapters shorter.
In everyday life: Look for KS 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 KS Persei in 20 minutes

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

Frequently asked questions

What is KS Persei in simple terms?

KS Persei is a binary system in the equatorial constellation of Perseus. It is sometimes known as Bidelman's Star, named after William P.

Why does KS 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 KS 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 KS Persei.