astronomy

Gliese 105

Gliese 105 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 105 rather than just read about it. In short: Gliese 105 (also known as 268 G. Ceti) is a triple star system in the constellation of Cetus.

Key takeaways

Gliese 105 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 105 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Gliese 105 from memory before moving on to harder problems.

Reference excerpt

Gliese 105 (also known as 268 G. Ceti) is a triple star system in the constellation of Cetus. It is located relatively near the Sun at a distance of 23.6 light years (7.2 parsecs). Despite this, even the brightest component is barely visible with the unaided eye (see Bortle scale). No planets have yet been detected around any of the stars in this system.

All three of the stars are less massive than the Sun. The brightest component is designated HD 16160, and is known as Gliese 105 A. It is a K-type main-sequence star, about 70% the mass of the Sun. This star is unusual because its eruptions appear to not conform to the Waldmeier effect—i.e., the strongest eruptions of HD 16160 are not the ones characterized by the fast eruption onset. A nearby star has a similar proper motion to Gliese 105 A, so it is assumed to be physically associated with the primary, and is known as Gliese 105 B. The two are visually separated by 165″, which corresponds to 1,200 astronomical units (au) given parallax. In 1994, Edward W. Weis announced that component B is a variable star. In 1997 it was given its variable star designation, BX Ceti. It is a BY Draconis variable star whose brightness varies between 11.64 and 11.68 magnitudes. A third companion, known as Gliese 105 C, lies much closer to A, currently at a distance of approximately 24 au. The pair A-C have an estimated orbital period of about 70 years. While detected directly, Gliese 105 C has also been observed to perturb Gliese 105 A from its usual position; from that, its orbit is estimated to have a high eccentricity of around 0.64 and a semimajor axis of 17 au. Gliese 105 C is an extremely faint red dwarf. It is roughly 8 to 9 percent the mass of the Sun, and it is about 20,000 times fainter than its parent star in visible light—at a distance of 1 au (the distance from the Earth to the Sun) it would only be four times brighter than the full moon.

Illustrations

Worked examples

Example 1 — a first encounter with Gliese 105

Start with the simplest possible case. Write down what Gliese 105 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 105 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 105 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 105

In research: Gliese 105 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 105 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 105 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bright Star Catalogue objects, Cetus (constellation), Durchmusterung objects, so understanding it makes those chapters shorter.
In everyday life: Look for Gliese 105 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 105 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Gliese 105 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 105 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Gliese 105 in simple terms?

Gliese 105 (also known as 268 G. Ceti) is a triple star system in the constellation of Cetus.

Why does Gliese 105 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 105?

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 105.