astronomy

Kepler-37b

Kepler-37b 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-37b rather than just read about it. In short: Kepler-37b is an exoplanet orbiting the star Kepler-37 in the constellation Lyra. As of February 2013, it is the smallest planet discovered around a main-sequence star, with a radius slightly greater than that of the Moon and slightly smaller than that of Mercury.

Key takeaways

Kepler-37b 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-37b to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Kepler-37b from memory before moving on to harder problems.

Reference excerpt

Kepler-37b is an exoplanet orbiting the star Kepler-37 in the constellation Lyra. As of February 2013, it is the smallest planet discovered around a main-sequence star, with a radius slightly greater than that of the Moon and slightly smaller than that of Mercury. The measurements do not constrain its mass, but masses above a few times that of the Moon give unphysically high densities.

Characteristics

Mass, radius and temperature

Kepler-37b is a sub-Earth, an exoplanet with a radius and mass smaller than Earth. Its equilibrium temperature is 718 K (445 °C; 833 °F). Because of its small size and high temperatures, it is not expected to have an atmosphere. Its radius is approximately 0.31 R🜨 (about 1,980 kilometres (1,230 mi)), slightly larger than the Moon (0.27 R🜨), but a little smaller than Mercury (0.38 R🜨). Due to its small size, it is very likely Kepler-37b is a rocky planet with a solid surface. Furthermore, it is too hot to support liquid water on its surface.

Host star

The planet orbits a (G-type) star similar to the Sun, named Kepler-37, orbited by a total of four planets. The star has a mass of 0.80 M☉ and a radius of 0.79 R☉. It has a temperature of 5417 K and is 5.66 billion years old. In comparison, the Sun is 4.6 billion years old, and has a temperature of 5778 K. The star's apparent magnitude, or how bright it appears from Earth's perspective, is 9.71. Therefore, it is too dim to be seen with the naked eye.

Orbit Kepler-37b orbits its parent star at a distance of about 15 million kilometers (9.3 million miles), with a period of roughly 13 days at a distance of 0.1 AU (compared to Mercury's distance from the Sun, which is about 0.38 AU). The outer two planets in the system have orbital periods within one percent of the 8:5 and 3:1 resonances with Kepler-37b's period.

Discovery Kepler-37b, along with two other planets, Kepler-37c and Kepler-37d, were discovered by the Kepler space telescope, which observes stellar transits. After observing transits of Kepler-37b, astronomers had to compare it with the size of the parent star. The size of the star was obtained using asteroseismology; Kepler-37 is currently the smallest star to be studied using this process. This allowed the size of Kepler-37b to be determined "with extreme accuracy". To date, Kepler-37b is the smallest planet discovered around a main-sequence star outside the Solar System. Detection of Kepler-37b was possible due to its short orbital period, relative brightness, and low activity of its host star, allowing brightness data to average out quickly. The discovery of Kepler-37b has led Jack Lissauer, a scientist at NASA's Ames Research Center, to conjecture that "such little planets are common".

See also List of exoplanet extremes List of smallest exoplanets

Notes

References

Illustrations

Worked examples

Example 1 — a first encounter with Kepler-37b

Start with the simplest possible case. Write down what Kepler-37b 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-37b 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-37b 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-37b

In research: Kepler-37b 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-37b 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-37b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exoplanets discovered by the Kepler space telescope, Exoplanets discovered in 2013, Kepler-37, so understanding it makes those chapters shorter.
In everyday life: Look for Kepler-37b 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-37b in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Kepler-37b 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-37b out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Kepler-37b in simple terms?

Why does Kepler-37b 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-37b?

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-37b.