astronomy

GL Virginis

GL Virginis 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 GL Virginis rather than just read about it. In short: GL Virginis, also known as G 12-30, is a star in the constellation of Virgo. It is a faint red dwarf, like more than 70% of the stars located within 10 parsecs (32.6 ly) of the Solar System; its magnitude visual magnitude is 13.898, making it impossible to see with the naked eye.

Key takeaways

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

Reference excerpt

GL Virginis, also known as G 12-30, is a star in the constellation of Virgo. It is a faint red dwarf, like more than 70% of the stars located within 10 parsecs (32.6 ly) of the Solar System; its magnitude visual magnitude is 13.898, making it impossible to see with the naked eye. In 1977, Glen J. Veeder and Olav L. Hansen announced that the star, then called GL 12-30, is a variable star. It was given its variable star designation, GL Virginis, in 1981. Located 21.1 light years (6.46 parsecs) away, GL Virginis has a spectral type of M4.5V and an effective temperature of approximately 3110 K. Its luminosity (emitted in the visible section of the electromagnetic spectrum) is only one ten-thousandth compared to the Sun; however, since a significant fraction of its radiation is emitted as invisible infrared light, its bolometric luminosity increases to 0.5% of that of the Sun. Its mass is 12% that of the Sun and its radius is 16% of the Sun. It is a fairly rapid rotator: its rotational velocity is least 17 km/s, which implies that it takes less than half a day to complete a rotation on its axis. The star is emitting frequent flares, with at least five detected by 2019. The closest known star system to GL Virginis is Gliese 486, 6.4 light-years away.

References

Illustrations

Worked examples

Example 1 — a first encounter with GL Virginis

Start with the simplest possible case. Write down what GL Virginis 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 GL Virginis 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 GL Virginis 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 GL Virginis

In research: GL Virginis 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 GL Virginis 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: GL Virginis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Gliese and GJ objects, M-type main-sequence stars, Objects with variable star designations, so understanding it makes those chapters shorter.
In everyday life: Look for GL Virginis 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 GL Virginis in 20 minutes

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

Frequently asked questions

What is GL Virginis in simple terms?

Why does GL Virginis 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 GL Virginis?

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 GL Virginis.