astronomy

Kepler-69

Kepler-69 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-69 rather than just read about it. In short: Kepler-69 (KOI-172, 2MASS J19330262+4452080, KIC 8692861) is a G-type main-sequence star similar to the Sun in the constellation Cygnus, located about 2,390 ly (730 pc) from Earth. On April 18, 2013 it was announced that the star has two planets.

Key takeaways

Kepler-69 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-69 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Kepler-69 from memory before moving on to harder problems.

Reference excerpt

Kepler-69 (KOI-172, 2MASS J19330262+4452080, KIC 8692861) is a G-type main-sequence star similar to the Sun in the constellation Cygnus, located about 2,390 ly (730 pc) from Earth. On April 18, 2013 it was announced that the star has two planets. Although initial estimates indicated that the terrestrial planet Kepler-69c might be within the star's habitable zone, further analysis showed that the planet very likely is interior to the habitable zone and is far more analogous to Venus than to Earth and thus completely inhospitable.

Nomenclature and history Prior to Kepler observation, Kepler-69 had the 2MASS catalogue number 2MASS J19330262+4452080. In the Kepler Input Catalog it has the designation of KIC 8692861, and when it was found to have transiting planet candidates it was given the Kepler object of interest number of KOI-172.

The star's planets were discovered by NASA's Kepler Mission, a mission tasked with discovering planets in transit around their stars. The transit method that Kepler uses involves detecting dips in brightness in stars. These dips in brightness can be interpreted as planets whose orbits move in front of their stars from the perspective of Earth. The name Kepler-69 derives directly from the fact that the star is the catalogued 69th star discovered by Kepler to have confirmed planets. The designations b, c derive from the order of discovery. The designation of b is given to the first planet orbiting a given star, followed by the other lowercase letters of the alphabet. In the case of Kepler-69, all of the known planets in the system were discovered at one time, so b is applied to the closest planet to the star and c to the farthest.

Stellar characteristics Kepler-69 is a G4 star that is approximately 81% the mass of and 93% the radius of the Sun. It has a surface temperature of 5638 ± 168 K and is 9.8 billion years old. In comparison, the Sun has a surface temperature of 5778 K and is 4.6 billion years old. The star's apparent magnitude, or how bright it appears from Earth's perspective, is 13.7. Therefore, Kepler-69 is too dim to be seen with the naked eye.

Planetary system Kepler-69 has two known planets orbiting around it. Kepler-69b is a hot super-Earth-sized exoplanet. Kepler-69c is a super-Earth-sized exoplanet, about 2.2 times larger than Earth. It receives a similar amount of flux from its star as Venus does from the Sun, and is thus a likely candidate for a super-Venus. Newer measurements suggest higher planetary radii than previous estimates: 2.80 and 2.17 R🜨 for Kepler 69 b and c respectively, in contrast with the earlier estimate from Barclay et al. (2013): 2.24 and 1.71 R🜨.

See also List of potentially habitable exoplanets Kepler-70

Notes

References

External links Kepler Mission – NASA. Kepler – Discoveries – Summary Table – NASA. Kepler – Discovery of New Planetary Systems (2013) Archived 2020-05-08 at the Wayback Machine. Kepler – Tally of Planets/interactive (2013) – NYT. Video (02:27) - NASA Finds Three New Planets in "Habitable Zone" (04/18/2013).

Illustrations

Worked examples

Example 1 — a first encounter with Kepler-69

Start with the simplest possible case. Write down what Kepler-69 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-69 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-69 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-69

In research: Kepler-69 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-69 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-69 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cygnus (constellation), G-type main-sequence stars, Kepler objects of interest, so understanding it makes those chapters shorter.
In everyday life: Look for Kepler-69 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-69 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Kepler-69 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-69 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Kepler-69 in simple terms?

Why does Kepler-69 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-69?

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-69.