astronomy

Gliese 867

Gliese 867 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 Gliese 867 rather than just read about it. In short: Gliese 867 is a quadruple star system located 29 light-years (8.9 parsecs) away in the constellation Aquarius. It is composed of two binary sub-systems, Gliese 867 A & B, also known by their variable star designations FK Aquarii and FL Aquarii.

Key takeaways

Gliese 867 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Gliese 867 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Gliese 867 from memory before moving on to harder problems.

Reference excerpt

Gliese 867 is a quadruple star system located 29 light-years (8.9 parsecs) away in the constellation Aquarius. It is composed of two binary sub-systems, Gliese 867 A & B, also known by their variable star designations FK Aquarii and FL Aquarii. Gliese 867 is the third-nearest quadruple system, after Gliese 570 and Mu Herculis, and the nearest such system where the primary star is a red dwarf. There are two closer quintuple systems, V1054 Ophiuchi and Xi Ursae Majoris, the former composed entirely of red dwarfs.

System

Gliese 867 A & B are separated by 24.5 arcseconds, corresponding to a projected distance of 216 AU. Both are spectroscopic binaries. Gliese 867 A & B are both flare stars and BY Draconis variables. They have been known to be flare stars since 1978.

Gliese 867 A (FK Aquarii)

Gliese 867 A, also known as FK Aquarii, is a close binary orbiting every 4.1 days. The companion star is also called Gliese 867 C. Both stars are red dwarfs around half the mass of the Sun. The system has been known to be a spectroscopic binary since 1965, at that time referred to by its Durchmusterung designation BD−21°6267A. It has also been characterized by astrometry from the Gaia space telescope. Both stars are magnetically active, and have strong dipolar magnetic fields resembling those found in lower-mass, fully convective red dwarfs. The primary star is the most massive red dwarf known to host this type of magnetic field as of 2024.

Gliese 867 B (FL Aquarii)

Gliese 867 B, also known as FL Aquarii, is a close binary orbiting every 1.8 days. It was found to be a spectrosopic binary in 2014. The primary star is a red dwarf, while the companion, Gliese 867 D, has a minimum mass of only 61±7 Jupiter masses, and so may be a brown dwarf.

Illustrations

Worked examples

Example 1 — a first encounter with Gliese 867

Start with the simplest possible case. Write down what Gliese 867 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 Gliese 867 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 Gliese 867 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 Gliese 867

In research: Gliese 867 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 Gliese 867 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: Gliese 867 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aquarius (constellation), Brown dwarfs, Durchmusterung objects, so understanding it makes those chapters shorter.
In everyday life: Look for Gliese 867 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 Gliese 867 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Gliese 867 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 Gliese 867 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Gliese 867 in simple terms?

Why does Gliese 867 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 Gliese 867?

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 Gliese 867.