astronomy

K2-25

K2-25 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 K2-25 rather than just read about it. In short: K2-25 is a young red dwarf star located in the Hyades cluster. There is a single known Neptune-sized planet in a 3.5 day orbit.

Key takeaways

K2-25 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect K2-25 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of K2-25 from memory before moving on to harder problems.

Reference excerpt

K2-25 is a young red dwarf star located in the Hyades cluster. There is a single known Neptune-sized planet in a 3.5 day orbit.

Hyades cluster Using proper motion measurements in a search for low-luminosity members of the Hyades cluster, William van Altena first identified the star vA 50 (later known as K2-25) as a probable cluster member. Membership in the Hyades cluster was later confirmed.

Properties

K2-25 is a red dwarf that is only 26% the mass of the Sun and less than 1% of the luminosity. As a member of the Hyades cluster, it is only 650 million years old as compared to the Sun's 4.5 billion. There is clear evidence for starspot activity in both the Kepler data and radial velocities as well as the associated activity indicators.

Planetary system The star has one known planet, K2-25b, with searches of the Kepler space telescope data for transits of additional planets being negative. Analysis of transit-timing variations from the Spitzer Space Telescope as well as the MEarth Project also found no evidence of additional planets.

Discovery Brightness measurements of K2-25 taken by the Kepler space telescope during its extended K2 mission led to the discovery of the transiting planet K2-25b.

Characteristics K2-25b is a Hot Neptune type planet in an eccentric 3.48 day orbit. Due to its proximity and the activity levels of its host star, K2-25b should be losing some of its atmosphere to space; however, observations of two transits by the Hubble Space Telescope to search for escaping neutral hydrogen were negative.

References

External links The Extrasolar Planets Encyclopaedia entry for K2-25b

Illustrations

Worked examples

Example 1 — a first encounter with K2-25

Start with the simplest possible case. Write down what K2-25 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 K2-25 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 K2-25 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 K2-25

In research: K2-25 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 K2-25 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: K2-25 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Hyades (star cluster), M-type main-sequence stars, Planetary systems with one confirmed planet, so understanding it makes those chapters shorter.
In everyday life: Look for K2-25 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 K2-25 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what K2-25 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 K2-25 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is K2-25 in simple terms?

K2-25 is a young red dwarf star located in the Hyades cluster. There is a single known Neptune-sized planet in a 3.5 day orbit.

Why does K2-25 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 K2-25?

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 K2-25.