astronomy

RT Virginis

RT 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 RT Virginis rather than just read about it. In short: RT Virginis is a variable star in the equatorial constellation of Virgo, abbreviated RT Vir. It ranges in brightness from an apparent visual magnitude of 7.7 down to 9.7, which is too faint to be visible to the naked eye.

Key takeaways

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

Reference excerpt

RT Virginis is a variable star in the equatorial constellation of Virgo, abbreviated RT Vir. It ranges in brightness from an apparent visual magnitude of 7.7 down to 9.7, which is too faint to be visible to the naked eye. Based on parallax measurements made with the VLBI, the distance to this star is approximately 740 light years. It is receding from the Sun with a radial velocity of 17 km/s. The long period variability of this star was discovered by W. P. Fleming in 1896, based on photographic plates taken between 1886 and 1895. It was listed with its variable star designation, RT Virginis, in Annie Jump Cannon's 1907 work Second Catalog of Variable Stars. A. H. Joy in 1942 categorized it as an irregular variable with a stellar classification of M8III. In 1969 it was classified as a semiregular variable star of the SRb type. The period was determined to be 155 days by P. N. Kholopov and associates in 1985, then re-evaluated as 375 days based on AAVSO light curves in 1997. This is an oxygen-rich red giant star on the asymptotic giant branch of its evolution, and is undergoing mass loss due to thermal pulsation. Water vapor emission in the vicinity of the star was detected in the microwave band by D. F. Dickinson in 1973. This is originating from strong maser emission in a circumstellar gas-dust shell. The flux density of these water masers is over 100 Jy. The star is losing mass at a rate of 3×10−6 M☉·yr−1; the equivalent of the Sun's mass in 3.3 million years. The velocity of the spherically expanding gas is as high as 11 km/s in the water maser region, at a radius of 5 to 25 AU. In a SiO emitting region located ~400 AU from the star, the gas velocity is 7.8 km/s. This outflow appears clumpy and asymmetrical with a strong temporal variation.

References

Illustrations

Worked examples

Example 1 — a first encounter with RT Virginis

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

In research: RT 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 RT 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: RT Virginis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1896, Asymptotic-giant-branch stars, Discoveries by Williamina Fleming, so understanding it makes those chapters shorter.
In everyday life: Look for RT 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 RT Virginis in 20 minutes

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

Frequently asked questions

What is RT Virginis in simple terms?

Why does RT 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 RT 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 RT Virginis.