astronomy

HD 93905

HD 93905 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 HD 93905 rather than just read about it. In short: HD 93905 (HR 4238) is a solitary star located in the southern constellation Antlia. The star has an absolute magnitude of 0 and an apparent magnitude of 5.61, making it faintly visible to the naked eye under ideal conditions.

Key takeaways

HD 93905 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect HD 93905 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 93905 from memory before moving on to harder problems.

Reference excerpt

HD 93905 (HR 4238) is a solitary star located in the southern constellation Antlia. The star has an absolute magnitude of 0 and an apparent magnitude of 5.61, making it faintly visible to the naked eye under ideal conditions. The star is located 371 light years away based on its parallax shift and is drifting closer with a helocentric radial velocity of −9.6 km/s. This star has a classification of A1 V, which indicates that it is an ordinary A-type main-sequence star that is fusing hydrogen at its core. At present it has 2.78 times the mass of the Sun but is large and over luminous for its class with 3.89 times and 101 times the radius and luminosity of the Sun respectively. This is because HD 93905 has already completed most of its main sequence lifetime at an age of 256 million years. HD 93905 has a surface temperature of 8,895 K and spins quickly with a projected rotational velocity of 85 km/s.

References

Illustrations

Worked examples

Example 1 — a first encounter with HD 93905

Start with the simplest possible case. Write down what HD 93905 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 HD 93905 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 HD 93905 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 HD 93905

In research: HD 93905 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 HD 93905 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: HD 93905 is common in secondary-school and first-year university syllabi. It links to neighbouring topics A-type main-sequence stars, Antlia, Bright Star Catalogue objects, so understanding it makes those chapters shorter.
In everyday life: Look for HD 93905 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 HD 93905 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 93905 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 HD 93905 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 93905 in simple terms?

Why does HD 93905 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 HD 93905?

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 HD 93905.