astronomy

HD 101782

HD 101782 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 101782 rather than just read about it. In short: HD 101782, also known as HR 4507, is a yellowish-orange hued star located in the southern circumpolar constellation of Chamaeleon. It has an apparent magnitude of 6.33, placing it near the limit for naked eye visibility.

Key takeaways

HD 101782 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 101782 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 101782 from memory before moving on to harder problems.

Reference excerpt

HD 101782, also known as HR 4507, is a yellowish-orange hued star located in the southern circumpolar constellation of Chamaeleon. It has an apparent magnitude of 6.33, placing it near the limit for naked eye visibility. Based on parallax measurements from Gaia DR3, the object is estimated to be 356 light years away from the Solar System. It appears to be receding with a heliocentric radial velocity of 11.5 km/s. De Mederios found the radial velocity to be variable, suggesting that it may be a spectroscopic binary. Eggen (1989) lists it as a member of the young disk population. HD 101782 has a stellar classification of K0 III, indicating that it is an evolved red giant. It is currently on the horizontal branch (HB), fusing helium at its core. The star is located on the cool end of the red clump, a region on the HR diagram with metal-rich HB stars. It has double the mass of the Sun but has expanded to 10.1 times its girth. It radiates 55 times the luminosity of the Sun from its photosphere at an effective temperature of 4,663 K. It has an iron abundance 110% that of the Sun's, placing it at solar metallicity. Like most giants it spins slowly, having a projected rotational velocity lower than 1.1 km/s. TYC 9507-3649-1 is a 10th magnitude optical companion located 25.9″ away along a position angle of 139°. This companion was first noticed by Sir John Herschel in 1837.

References

Illustrations

Worked examples

Example 1 — a first encounter with HD 101782

Start with the simplest possible case. Write down what HD 101782 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 101782 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 101782 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 101782

In research: HD 101782 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 101782 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 101782 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bright Star Catalogue objects, Chamaeleon, Double stars, so understanding it makes those chapters shorter.
In everyday life: Look for HD 101782 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 101782 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 101782 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 101782 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 101782 in simple terms?

Why does HD 101782 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 101782?

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 101782.