astronomy

Struve 2398

Struve 2398 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 Struve 2398 rather than just read about it. In short: Struve 2398 (Gliese 725) is a binary star system in the northern constellation of Draco. Struve 2398 is star number 2398 in the Struve Double Star Catalog of Russian-German astronomer Friedrich Georg Wilhelm von Struve.

Key takeaways

Struve 2398 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Struve 2398 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Struve 2398 from memory before moving on to harder problems.

Reference excerpt

Struve 2398 (Gliese 725) is a binary star system in the northern constellation of Draco. Struve 2398 is star number 2398 in the Struve Double Star Catalog of Russian-German astronomer Friedrich Georg Wilhelm von Struve. The astronomer's surname, and hence the star identifier, is sometimes indicated by a Greek sigma, Σ; hence, this system can be listed with the identifier Σ 2398. Although the components are too faint to be viewed with the naked eye, this star system is among the closest to the Sun. Parallax measurements by the Gaia spacecraft give them an estimated distance of 11.5 light-years (3.5 parsecs) away. Both stars are small red dwarfs, with each having around a third the Sun's mass and radius. They are each sources of X-ray emission. They are orbiting with a period of about 871 years, at a separation of about 63 astronomical units with an orbital eccentricity of 0.29. The pair has a relatively high proper motion of 2.2 arc seconds per year. The system is on an orbit through the Milky Way that has an eccentricity of 0.05, carrying them as close as 8 kpc and as far as 9 kpc from the Galactic Center. The plane of their galactic orbit carries them as far as 463−489 pc away from the galactic plane.

Planetary systems Both stars of the Struve 2398 system are known to host planets. Struve 2398 A has one known planet, a likely super-Earth discovered in 2024 using the radial velocity method. This planet has a minimum mass 2.8 times that of Earth, and has a close orbit with a period of 11 days; it is too close to its star to be in the habitable zone. TESS observations show that the planet likely does not transit its host star. Struve 2398 B also hosts one known planet, a super-Earth orbiting within the habitable zone, circling its host star every 37.9 days. An additional planet with an orbital period of 4.765 days is suspected. Both were detected using the radial velocity method and announced in 2025. Other planetary candidates had previously been proposed around star B, but were not confirmed.

See also Other systems with multiple planet-hosting stars:

55 Cancri HD 20781 & HD 20782 HD 133131 WASP-94 XO-2

References

External links SolStation entry http://www.daviddarling.info/encyclopedia/S/Struve2398.html http://jumk.de/astronomie/near-stars/struve-2398.shtml Struve 2398 in Dra

Worked examples

Example 1 — a first encounter with Struve 2398

Start with the simplest possible case. Write down what Struve 2398 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 Struve 2398 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 Struve 2398 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 Struve 2398

In research: Struve 2398 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 Struve 2398 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: Struve 2398 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Binary stars, Draco (constellation), Durchmusterung objects, so understanding it makes those chapters shorter.
In everyday life: Look for Struve 2398 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 Struve 2398 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Struve 2398 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 Struve 2398 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Struve 2398 in simple terms?

Why does Struve 2398 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 Struve 2398?

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 Struve 2398.