astronomy

Omicron Aquarii

Omicron Aquarii 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 Omicron Aquarii rather than just read about it. In short: Omicron Aquarii is a variable star in the equatorial constellation of Aquarius. Its name is a Bayer designation that is Latinized from ο Aquarii, and abbreviated Omicron Aqr or ο Aqr.

Key takeaways

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

Reference excerpt

Omicron Aquarii is a variable star in the equatorial constellation of Aquarius. Its name is a Bayer designation that is Latinized from ο Aquarii, and abbreviated Omicron Aqr or ο Aqr. Visible to the naked eye, it has an apparent visual magnitude of +4.71. Parallax measurements put it at a distance of roughly 466 light-years (143 parsecs) from Earth. It is drifting further away with a radial velocity of +11 km/s. The star is a candidate member of the Pisces-Eridanus stellar stream of co-moving stars. It has the traditional star name Kae Uh, from the Chinese 蓋屋 (Mandarin pronunciation Gài Wū). In Chinese astronomy, 蓋屋 is the rooftop, an asterism consisting of ο Aquarii and 32 Aquarii. Consequently, the Chinese name for ο Aquarii itself is 蓋屋一 (Gài Wū yī, English: the First Star of Roofing.)

Properties

The spectrum of Omicron Aquarii fits a stellar classification of B5V, indicating that this is a main sequence star. Omicron Aquarii has 4.2 times the mass of the Sun and four times the Sun's radius. It is radiating 644 times the luminosity of the Sun from its photosphere at an effective temperature of 11,145 K. This is classified as a Gamma Cassiopeiae type variable star and its brightness varies from magnitude +4.68 down to +4.89. It is likely a single star, with no stellar companions. This star is spinning rapidly with an equatorial rotational velocity of 368 km/s, which is ~96% of the star's critical rotation velocity of 391 km/s. This is creating an equatorial bulge with a radius of 6.8±1.0 R☉ compared to a polar radius of 6.0±0.8 R☉. As a result, the polar temperature 11,500±578 K; higher than the equator. The emission lines are being generated by a decreted circumstellar disk of hot hydrogen gas. This disk has been globally stable for at least twenty years, as of 2020. It is inclined at an angle of 75°±3° to the plane of the sky. 90% of the hydrogen emission comes from within 9.5 stellar radii of the host star, and the disk has an estimated mass of ∼1.8×10−10 of the star's mass.

References

External links Image Omicron Aquarii

Illustrations

Worked examples

Example 1 — a first encounter with Omicron Aquarii

Start with the simplest possible case. Write down what Omicron Aquarii 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 Omicron Aquarii 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 Omicron Aquarii 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 Omicron Aquarii

In research: Omicron Aquarii 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 Omicron Aquarii 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: Omicron Aquarii is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aquarius (constellation), B-type main-sequence stars, Bayer objects, so understanding it makes those chapters shorter.
In everyday life: Look for Omicron Aquarii 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 Omicron Aquarii in 20 minutes

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

Frequently asked questions

What is Omicron Aquarii in simple terms?

Omicron Aquarii is a variable star in the equatorial constellation of Aquarius. Its name is a Bayer designation that is Latinized from ο Aquarii, and abbreviated Omicron Aqr or ο Aqr.

Why does Omicron Aquarii 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 Omicron Aquarii?

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 Omicron Aquarii.