astronomy

Kepler-8

Kepler-8 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-8 rather than just read about it. In short: Kepler-8 is a star located in the constellation Lyra in the field of view of the Kepler Mission, a NASA-led operation tasked with discovering terrestrial planets. The star, which is slightly hotter, larger, and more massive than the Sun, has one gas giant in its orbit, Kepler-8b.

Key takeaways

Kepler-8 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-8 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Kepler-8 from memory before moving on to harder problems.

Reference excerpt

Kepler-8 is a star located in the constellation Lyra in the field of view of the Kepler Mission, a NASA-led operation tasked with discovering terrestrial planets. The star, which is slightly hotter, larger, and more massive than the Sun, has one gas giant in its orbit, Kepler-8b. This gas giant is larger than Jupiter, but is less massive, and thus more diffuse. The planet's discovery was announced to the public on January 4, 2010 along with four other planets. As the fifth confirmed planetary system verified by Kepler, it helped demonstrate the capabilities of the Kepler spacecraft.

Nomenclature and history Kepler-8 was named the way it was because it is home to the eighth planetary system confirmed during the course of the Kepler Mission, a NASA-directed program tasked with searching a region of the sky for terrestrial planets that transit, or cross in front of (and thereby, for a while, make dimmer) the stars that they orbit with respect to Earth. The planet in orbit around Kepler-8, Kepler-8b, was the fifth of the first five planets discovered by the Kepler spacecraft; the first three planets confirmed by Kepler had been previously discovered, and were only used to verify the accuracy of Kepler's measurements. Kepler-8b's discovery was announced to the public on January 4, 2010 at the 215th meeting of the American Astronomical Society in Washington, D.C., alongside planets in orbit around Kepler-4, Kepler-5, Kepler-6, and Kepler-7. The data that was used to identify Kepler-8b's existence was re-examined and verified by observatories in Hawaii, Arizona, Texas, California, and the Canary Islands.

Characteristics Kepler-8 is situated some 1020 pc (or 3,300 light years) from Earth. With a mass of 1.213 Msun and a radius of 1.486 Rsun, Kepler-8 is more massive than the Sun by about a fifth of the Sun's mass, and is nearly three halves its size. The star is predicted to be 3.84 (± 1.5) billion years old, compared to the Sun's age at 4.6 billion years. Kepler-8 has a metallicity of [Fe/H] = -0.055 (± 0.03), making it 12% less metal-rich than the metal-rich Sun; metallicity is important in stars because stars richer in metal are more likely to harbor planets. The star also has an effective temperature of 6213 (± 150) K, meaning that it is hotter than the Sun, which has an effective temperature of 5778 K.

Kepler-8 has an apparent magnitude of 13.9; in other words, as seen from Earth, Kepler-8 is an extremely dim star. It cannot be seen with the naked eye.

Planetary system Kepler-8b is the only planet that has been discovered orbiting of Kepler-8. With a mass of .603 MJ and a radius of 1.419 RJ, the planet is 60% the mass of, but 42% larger than planet Jupiter. The planet is diffuse, with a density of .261 grams/cc, especially in comparison to Jupiter and its density of 5.515 grams/cc. At a distance of .0483 AU, Kepler-8b orbits its star every 3.5225 days. The eccentricity of Kepler-8 is assumed to be 0, which would give the planet a circular orbit. In comparison, planet Mercury orbits the Sun at .3871 AU every 87.97 days. Mercury also has an elliptical orbit, with an eccentricity of .2056.

See also List of extrasolar planets Kepler Mission Hot Jupiter

References

Worked examples

Example 1 — a first encounter with Kepler-8

Start with the simplest possible case. Write down what Kepler-8 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-8 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-8 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-8

In research: Kepler-8 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-8 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-8 is common in secondary-school and first-year university syllabi. It links to neighbouring topics F-type main-sequence stars, Kepler objects of interest, Lyra, so understanding it makes those chapters shorter.
In everyday life: Look for Kepler-8 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-8 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Kepler-8 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-8 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Kepler-8 in simple terms?

Why does Kepler-8 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-8?

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-8.