astronomy

Kepler-1638

Kepler-1638 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-1638 rather than just read about it. In short: Kepler-1638 is a G-type subgiant star located about 5,000 light years away in the constellation of Cygnus. One known exoplanet has been found orbiting the star: Kepler-1638b.As of January 2021, Kepler-1638 is the farthest star with a known exoplanet orbiting in the habitable zone.

Key takeaways

Kepler-1638 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-1638 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Kepler-1638 from memory before moving on to harder problems.

Reference excerpt

Kepler-1638 is a G-type subgiant star located about 5,000 light years away in the constellation of Cygnus. One known exoplanet has been found orbiting the star: Kepler-1638b.As of January 2021, Kepler-1638 is the farthest star with a known exoplanet orbiting in the habitable zone.

Planetary system

Kepler-1638 b is an exoplanet in orbit of its star, Kepler-1638, located in the constellation Cygnus. It was confirmed in 2016 as part of a study statistically validating hundreds of Kepler planets. Based on the parameters in the discovery paper, the planet is a super-Earth, with a radius of 1.87+0.33−0.22 R🜨, and a predicted mass of 4.16 Earths. It has an orbit of 259.337±0.013 days in its system's habitable zone and orbits 0.745 AU from its star. It is the most distant known exoplanet that is considered potentially habitable. However, these parameters were estimated before the first measurement of the host star's parallax was published as part of Gaia DR2 in 2018. The Gaia parallax suggests a distance of about 1,548 parsecs (5,050 light-years), much farther than the pre-Gaia estimate of about 764 parsecs (2,490 light-years). This revised distance results in a significantly larger estimate of the radius of the star, and thus of the planet, with a 2018 study finding a planetary radius of 3.226+0.201−0.315 R🜨. This would make the planet an ice giant like Neptune, and thus not potentially habitable in an Earth-like sense.

References

See also List of potentially habitable exoplanets

Illustrations

Worked examples

Example 1 — a first encounter with Kepler-1638

Start with the simplest possible case. Write down what Kepler-1638 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-1638 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-1638 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-1638

In research: Kepler-1638 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-1638 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-1638 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-1638 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-1638 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Kepler-1638 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-1638 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Kepler-1638 in simple terms?

Why does Kepler-1638 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-1638?

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-1638.