astronomy

Theta Aquilae

Theta 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 Theta Aquilae rather than just read about it. In short: Theta Aquilae, also named Antinous, is a binary star in the equatorial constellation Aquila. Its identifier is a Bayer designation that is Latinized from θ Aquilae, and abbreviated Theta Aql or θ Aql.

Key takeaways

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

Reference excerpt

Theta Aquilae, also named Antinous, is a binary star in the equatorial constellation Aquila. Its identifier is a Bayer designation that is Latinized from θ Aquilae, and abbreviated Theta Aql or θ Aql. The combined apparent visual magnitude of the pair is 3.26, making it the fourth-brightest member of the constellation. This distance to this system can be determined through the parallax technique, yielding an estimate of roughly 286 light-years (88 parsecs) from Earth. It is drifting closer with a heliocentric radial velocity of −27 km/s.

Properties Theta Aquilae is a double-lined spectroscopic binary, which indicates that the individual components have not been viewed through a telescope; instead, what can be observed is their combined spectrum with the individual absorption line features shifting back and forth over the course of an orbit because of the Doppler effect. Their orbit has a period of 17.1 days with a large orbital eccentricity is 0.60. At the estimated distance of this system, the angular separation of 3.2 milliarcseconds corresponds to a physical separation of about 0.24–0.28 au. A 2007 study classified both stars with a matching stellar classification of B9.5 III, suggesting that they are massive, B-type giant stars that have exhausted the supply of hydrogen at their cores and evolved away from the main sequence of stars like the Sun. Hummel et al. (1996) gave the primary component, θ Aql A, an estimated mass of 3.6 solar, a radius 4.8 the Sun's, and 278 the luminosity of the Sun. For the secondary component, θ Aql B, they give the corresponding parameters as 2.9 times the mass, 2.4 times the radius and 68 times the luminosity of the Sun. Based upon their estimated parameters, Kaler (2008) suggests that θ Aql A is actually a subgiant star, while θ Aql B is a main sequence star. Adelman et al (2015) confirm the main sequence status of the secondary component, and find that it is a weak Am star with overabundances of zirconium and barium.

Etymology In Chinese, 天桴 (Tiān Fú), meaning Celestial Drumstick, refers to an asterism consisting of θ Aquilae, 62 Aquilae, 58 Aquilae and η Aquilae. Consequently, the Chinese name for θ Aquilae itself is 天桴一 (Tiān Fú yī, English: the First Star of Celestial Drumstick.) R. H. Allen's Star Names writes this name as Tseen Foo, applied specifically to θ Aquilae and translated as Heavenly Raft. (See also τ Aquilae.) In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Thanih Ras al Akab (تاني ألرأس ألعقاب - taanii al ra’s alʕuqāb), which was translated into Latin as Secunda Capitis Vulturis, meaning the second (star) of eagle's head. This star, along with δ Aql and η Aql, were Al Mizān (ألميزان), the Scale-beam. According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Mizān were the title for three stars :δ Aql as Al Mizān I, η Aql as Al Mizān II and θ Aql as Al Mizān III. This star, together with η Aql, δ Aql, ι Aql, κ Aql and λ Aql, constituted the obsolete constellation Antinous. The IAU Working Group on Star Names approved the name Antinous for Theta Aquilae A on 16 May 2024, after the obsolete constellation, and it is now so entered in the IAU Catalog of Star Names.

References

External links Image Theta Aquilae The Constellations and Named Stars

Illustrations

Worked examples

Example 1 — a first encounter with Theta Aquilae

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

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

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

Frequently asked questions

What is Theta Aquilae in simple terms?

Why does Theta 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 Theta 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 Theta Aquilae.