astronomy

Phi Ursae Majoris

Phi Ursae Majoris 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 Phi Ursae Majoris rather than just read about it. In short: Phi Ursae Majoris, Latinized from φ Ursae Majoris, is a binary star system in the northern constellation of Ursa Major. It is white-hued and is visible to the naked eye with a combined apparent visual magnitude of +4.60; the primary is magnitude 5.28 while the secondary is magnitude 5.39.

Key takeaways

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

Reference excerpt

Phi Ursae Majoris, Latinized from φ Ursae Majoris, is a binary star system in the northern constellation of Ursa Major. It is white-hued and is visible to the naked eye with a combined apparent visual magnitude of +4.60; the primary is magnitude 5.28 while the secondary is magnitude 5.39. The system is located at a distance of approximately 510 light-years (160 parsecs) from the Sun based on parallax, but is drifting closer with a radial velocity of −14.7 km/s. It should make its closest approach at a distance of around 370 light-years in about 4.7 million years. As of 2017, the components had an angular separation of 0.50″ along a position angle of 304°. They are orbiting each other with a period of 105.4 years and eccentricity of 0.44. Both of components are A-type subgiant stars with a stellar classification of A3 IV. Phi Ursae Majoris is moving through the galaxy at a speed of 21.6 km/s relative to the Sun. Its projected galactic orbit carries it between 24,000 and 46,000 light-years from the center of the galaxy.

Naming With τ, h, υ, θ, e, and f, it composed the Arabic asterism Sarīr Banāt al-Na'sh, the Throne of the daughters of Na'sh, and Al-Haud, the Pond. According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al-Haud were the title for seven stars: f as Alhaud I, τ as Alhaud II, e as Alhaud III, h as Alhaud IV, θ as Alhaud V, υ as Alhaud VI and this star (φ) as Alhaud VII. In Chinese, 文昌 (Wén Chāng), meaning Administrative Center, refers to an asterism consisting of φ Ursae Majoris, υ Ursae Majoris, θ Ursae Majoris, 15 Ursae Majoris and 18 Ursae Majoris. Consequently, the Chinese name for φ Ursae Majoris itself is known as 文昌三 (Wén Chāng sān, English: the Third Star of Administrative Center).

References

Worked examples

Example 1 — a first encounter with Phi Ursae Majoris

Start with the simplest possible case. Write down what Phi Ursae Majoris 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 Phi Ursae Majoris 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 Phi Ursae Majoris 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 Phi Ursae Majoris

In research: Phi Ursae Majoris 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 Phi Ursae Majoris 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: Phi Ursae Majoris is common in secondary-school and first-year university syllabi. It links to neighbouring topics A-type subgiants, Bayer objects, Binary stars, so understanding it makes those chapters shorter.
In everyday life: Look for Phi Ursae Majoris 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 Phi Ursae Majoris in 20 minutes

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

Frequently asked questions

What is Phi Ursae Majoris in simple terms?

Why does Phi Ursae Majoris 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 Phi Ursae Majoris?

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 Phi Ursae Majoris.