astronomy

Phi Aquilae

Phi Aquilae 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 Aquilae rather than just read about it. In short: Phi Aquilae is a binary star system in the equatorial constellation of Aquila. Its name is a Bayer designation that is Latinized from φ Aquilae, and abbreviated Phi Aql or φ Aql.

Key takeaways

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

Reference excerpt

Phi Aquilae is a binary star system in the equatorial constellation of Aquila. Its name is a Bayer designation that is Latinized from φ Aquilae, and abbreviated Phi Aql or φ Aql. The system has an apparent visual magnitude of +5.28 and is visible to the naked eye as a faint point of light. With an annual parallax shift of 14.7 mas, this star is located at a distance of approximately 221 light-years (68 parsecs) from Earth. It is drifting closer with a radial velocity of −27 km/s. Based on its motion through space, this system is a candidate member of the nearby Argus association of co-moving stars, although it may be too old. Phi Aquilae is a single-lined spectroscopic binary with an orbital period of 3.32067 days. The pair have a projected separation of 190.4 AU as of 2008. The primary component is a subgiant star with a stellar classification of A1 IV. The star is around 280 million years old and is spinning with a projected rotational velocity of 27 km/s. It has 2.39 times the mass of the Sun and somewhere in the range of 1.8–2.5 times the Sun's radius. The outer atmosphere has an effective temperature of 9,509 K, giving it the white-hued appearance of an A-type star. It is radiating 34 times the luminosity of the Sun. The orbiting companion may be the source of the X-ray emission from this system, as stars similar to the primary component do not generally produce detectable levels of X-rays. It has 40% of the mass of the Sun. Based on photometric data from the TESS mission, the pair may undergo grazing eclipses. This implies an orbital inclination of at least 79°, and constrains the mass of the secondary to 0.5 M☉. A third component of this system was detected during the VAST survey. This faint component lies at an angular separation of 2.83 arcseconds, for a projected separation of 190 AU and an estimated orbital period of over 1,500 years.

References

External links Simbad Phi Aquilae Image HR 7610

Illustrations

Worked examples

Example 1 — a first encounter with Phi Aquilae

Start with the simplest possible case. Write down what Phi Aquilae 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 Aquilae 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 Aquilae 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 Aquilae

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

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

Frequently asked questions

What is Phi Aquilae in simple terms?

Phi Aquilae is a binary star system in the equatorial constellation of Aquila. Its name is a Bayer designation that is Latinized from φ Aquilae, and abbreviated Phi Aql or φ Aql.

Why does Phi Aquilae 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 Aquilae?

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 Aquilae.