astronomy

HD 161988

HD 161988 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 161988 rather than just read about it. In short: HD 161988, also known as HR 6635, is a solitary, orange hued star located in the southern circumpolar constellation Apus. It has an apparent magnitude of 6.07, allowing it to be faintly visible to the naked eye.

Key takeaways

HD 161988 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 161988 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 161988 from memory before moving on to harder problems.

Reference excerpt

HD 161988, also known as HR 6635, is a solitary, orange hued star located in the southern circumpolar constellation Apus. It has an apparent magnitude of 6.07, allowing it to be faintly visible to the naked eye. Parallax measurements place it at a distance of 621 light years, and it is currently receding with a heliocentric radial velocity of 36.8 km/s. The object has a stellar classification of K2 III, indicating that it is a red giant. Gaia Data Release 3 models place it on the red giant branch. At present it has 3.05 times the mass of the Sun and an enlarged radius of 20.8 R☉. It shines at 185 times the luminosity of the Sun from its photosphere at an effective temperature of 4,498 K. HD 161988 has an iron abundance 74% that of the Sun, making it slightly metal deficient. Like most giants, it spins modestly with a projected rotational velocity of 2.1 km/s. HD 161988 has a 14th magnitude optical companion located 26.4 arcseconds away along a position angle of 122°.

References

External links Image HD 161988

Worked examples

Example 1 — a first encounter with HD 161988

Start with the simplest possible case. Write down what HD 161988 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 161988 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 161988 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 161988

In research: HD 161988 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 161988 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 161988 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Apus, Bright Star Catalogue objects, Double stars, so understanding it makes those chapters shorter.
In everyday life: Look for HD 161988 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 161988 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 161988 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 161988 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 161988 in simple terms?

Why does HD 161988 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 161988?

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 161988.