astronomy

V1401 Aquilae

V1401 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 V1401 Aquilae rather than just read about it. In short: V1401 Aquilae is a single, semi-regular pulsating star in the equatorial constellation of Aquila. It has the designation HD 190390 from the Henry Draper Catalogue, and was formerly designated 64 Sagittarii.

Key takeaways

V1401 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 V1401 Aquilae to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of V1401 Aquilae from memory before moving on to harder problems.

Reference excerpt

V1401 Aquilae is a single, semi-regular pulsating star in the equatorial constellation of Aquila. It has the designation HD 190390 from the Henry Draper Catalogue, and was formerly designated 64 Sagittarii. The evolutionary status of the star is unclear, and it has been classified as a post-AGB object, a UU Herculis variable, or belonging to the W Virginis variable subclass of the type II Cepheids. It is dimly visible to the naked eye with an apparent visual magnitude that fluctuates around 6.3. Based on parallax measurements, it is located at a distance of approximately 2,380 light years. It lies 21.5° from the galactic plane. The variability of this star was announced by W. Strohmeier and associates in 1965. C. Waelkens and M. Burnet in 1985 found an irregular photometric variation with a period of around a month and suggested it is a candidate UU Herculis variable. J. D. Fernie in 1986 confirmed the variability and tentatively identified periods of 28.4 and 11.8 days. He found a very low gravity with shell-like features, suggesting potential mass loss. An analysis of the chemical composition by R. E. Luck and associates in 1990 found a mild enhancement of s-process elements as well as lithium, indicating it may have evolved from a lithium-rich giant. The stellar classification of V1401 Aql is F2II, matching an F-type bright giant. There is strong evidence that this star belongs to the population II cepheids, and it may be a W Virginis variable. On the Hertzsprung–Russell diagram it lies on the blue (hot) side of the Cepheid instability strip for population II stars. Membership in the UU Herculis variable class seems less likely since it has a relatively normal radial velocity and no infrared excess has been detected. The pulsation period of 28.6 days has been confirmed, but the pulsational behavior of this star is complex and it is not successfully modeled using a simple harmonic radial pulsation. The star is strongly metal deficient by a factor of 40, meaning the abundances of higher mass elements is much lower than in the Sun. There is a mild enhancement of s-process elements, although this is not considered to be intrinsic. Some investigators have suspected the star to be in an evolutionary stage following the asymptotic giant branch, but this is not confirmed based on chemical abundances.

References

Illustrations

Worked examples

Example 1 — a first encounter with V1401 Aquilae

Start with the simplest possible case. Write down what V1401 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 V1401 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 V1401 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 V1401 Aquilae

In research: V1401 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 V1401 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: V1401 Aquilae is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aquila (constellation), Bright Star Catalogue objects, Double stars, so understanding it makes those chapters shorter.
In everyday life: Look for V1401 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 V1401 Aquilae in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what V1401 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 V1401 Aquilae out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is V1401 Aquilae in simple terms?

Why does V1401 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 V1401 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 V1401 Aquilae.