astronomy

KOI-256

KOI-256 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 KOI-256 rather than just read about it. In short: KOI-256 is a double star located in the constellation Draco approximately 575 light-years (176 pc) from Earth. While observations by the Kepler spacecraft suggested the system contained a gas giant exoplanet orbiting a red dwarf, later studies determined that KOI-256 was a binary system composed of the red dwarf orbiting a white dwarf.

Key takeaways

KOI-256 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect KOI-256 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of KOI-256 from memory before moving on to harder problems.

Reference excerpt

KOI-256 is a double star located in the constellation Draco approximately 575 light-years (176 pc) from Earth. While observations by the Kepler spacecraft suggested the system contained a gas giant exoplanet orbiting a red dwarf, later studies determined that KOI-256 was a binary system composed of the red dwarf orbiting a white dwarf.

Name

The acronym "KOI" comes from Kepler object of interest and means that the object has been cataloged by the Kepler spacecraft during its search for extrasolar planets using the transit method. The "256" is the number of the object.

Characteristics

Initial observations by the Kepler spacecraft suggested a central red dwarf with a mass of 0.65 M☉, a radius of 1.1 R☉, and a temperature of 3,639 K (3,366 °C; 6,091 °F). Its candidate exoplanet was estimated to have a mass of 14.8 M🜨, a radius of 25.34 R🜨, an orbital period of 1.38 days, a temperature of 1,160 K (890 °C; 1,630 °F), and a semi-major axis of 0.021 astronomical units. Further studies by Muirhead et al. (2012) refined the candidate exoplanet parameters to a radius of 5.60±0.76 R🜨, a temperature of 726 K (453 °C; 847 °F), and a semi-major axis of 0.016 AU. Muirhead et al. (2013) performed additional observations with the Hale Telescope at Palomar Observatory. Using the radial velocity method for exoplanet detection, Muirhead's team found that the red dwarf was wobbling too much to be caused by a planetary mass object, and was more likely being influenced by a white dwarf. Using ultraviolet data from the GALEX spacecraft, it was seen that the red dwarf was significantly active, further suggesting perturbations by a white dwarf. The team re-analyzed Kepler's data, and found that when the white dwarf passed in front of the red dwarf, the red dwarf's light noticeably warped and brightened, an effect called gravitational lensing. While only being slightly larger than the Earth, the white dwarf has such large mass that the physically larger red dwarf orbits around its smaller companion. With the new observations, the red dwarf was shown to have a mass of 0.51±0.15 M☉, a radius of 0.540±0.014 R☉, and a temperature of 3,450 ± 50 K (3,180 ± 50 °C; 5,750 ± 90 °F). The white dwarf has a mass of 0.592±0.084 M☉, a radius of 0.01345±0.00091 R☉, and a temperature of 7,100 ± 800 K (6,800 ± 800 °C; 12,300 ± 1,400 °F).

References

Illustrations

Worked examples

Example 1 — a first encounter with KOI-256

Start with the simplest possible case. Write down what KOI-256 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 KOI-256 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 KOI-256 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 KOI-256

In research: KOI-256 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 KOI-256 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: KOI-256 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 2009, Draco (constellation), Eclipsing binaries, so understanding it makes those chapters shorter.
In everyday life: Look for KOI-256 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 KOI-256 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what KOI-256 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 KOI-256 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is KOI-256 in simple terms?

Why does KOI-256 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 KOI-256?

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 KOI-256.