astronomy

Kepler-36

Kepler-36 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 Kepler-36 rather than just read about it. In short: Kepler-36 is a star in the constellation of Cygnus with two known planets. It has an anomalously large radius, meaning that it is a subgiant.

Key takeaways

Kepler-36 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Kepler-36 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Kepler-36 from memory before moving on to harder problems.

Reference excerpt

Kepler-36 is a star in the constellation of Cygnus with two known planets. It has an anomalously large radius, meaning that it is a subgiant.

Planetary system

On June 21, 2012, the discovery of two planets orbiting the star was announced. The planets, a super-Earth and a mini-Neptune, are unusual in that they have very close orbits; their semi-major axes differ by only 0.013 AU. The outer planet orbits only 11% farther than the inner one. Coupled with masses significantly higher than Earth, their gravitational influence to each other is significant, meaning that their interaction causes extreme transit timing variations for both. Kepler-36b and c have estimated densities of 6.8 and 0.86 g/cm3, respectively. The two planets are close to a 7:6 orbital resonance. Kepler-36 is the most compact known resonant system with the 7:6 mean-motion resonance marking the last attainable stable period ratio. The large difference in densities, despite the close proximity of the planets' orbits, is likely due to the large difference in mass. The innermost and less massive planet likely lost most, or all, of the hydrogen/helium envelope acquired during formation.

References

External links Kepler mission discoveries

Worked examples

Example 1 — a first encounter with Kepler-36

Start with the simplest possible case. Write down what Kepler-36 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 Kepler-36 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 Kepler-36 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 Kepler-36

In research: Kepler-36 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 Kepler-36 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: Kepler-36 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cygnus (constellation), G-type subgiants, Kepler objects of interest, so understanding it makes those chapters shorter.
In everyday life: Look for Kepler-36 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 Kepler-36 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Kepler-36 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 Kepler-36 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Kepler-36 in simple terms?

Kepler-36 is a star in the constellation of Cygnus with two known planets. It has an anomalously large radius, meaning that it is a subgiant.

Why does Kepler-36 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 Kepler-36?

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 Kepler-36.