astronomy

HD 165185

HD 165185 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 165185 rather than just read about it. In short: HD 165185 is the Henry Draper Catalogue designation for a star in the southern zodiac constellation of Sagittarius. It has an apparent visual magnitude of 5.94, which indicates it is a sixth magnitude star that is faintly visible to the naked eye.

Key takeaways

HD 165185 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 165185 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 165185 from memory before moving on to harder problems.

Reference excerpt

HD 165185 is the Henry Draper Catalogue designation for a star in the southern zodiac constellation of Sagittarius. It has an apparent visual magnitude of 5.94, which indicates it is a sixth magnitude star that is faintly visible to the naked eye. (According to the Bortle scale, it can be viewed from dark suburban skies.) Parallax measurements give an estimated distance of 55.8 light years from the Sun. It is drifting further away with a heliocentric radial velocity of +15.4 km/s. This star is a pre-main-sequence solar analog with a stellar classification of G1 V. It is spinning with a projected rotational velocity of 7.53 km/s and a rotation period of 5.9 days. Measurements of magnetic activity in the chromosphere show variations over time, much like the sunspot cycle. This activity showed a distinct peak in 2009. Stellar models give an estimated mass equal to 1.13 times the mass of the Sun, but only 94% of the Sun's radius. The total, or bolometric luminosity of the star is 15% higher than the Sun, while the abundance of elements other than hydrogen and helium—what astronomer's term the metallicity—is nearly the same as in the Sun. The stellar atmosphere has an effective temperature of 5,940 K, giving it the yellow-hued glow of a G-type star. HD 165185 completed its perihelion passage some 851,000 years ago when it came within 29 ly (8.9 pc) of the Sun, and it is now moving away with a radial velocity component of 15.4 km/s. Based upon the motion of this star through space, its age, and properties, this star is a probable member of the Ursa Major Moving Group; a stellar kinematic group that formed in the same region of space. It has a suspected common proper motion companion at an angular separation of 12″, corresponding to a projected separation of 220 AU. This is a red dwarf star with a stellar classification of M0 and an infrared K band magnitude of 8.11.

References

Illustrations

Worked examples

Example 1 — a first encounter with HD 165185

Start with the simplest possible case. Write down what HD 165185 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 165185 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 165185 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 165185

In research: HD 165185 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 165185 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 165185 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bright Star Catalogue objects, Double stars, Durchmusterung objects, so understanding it makes those chapters shorter.
In everyday life: Look for HD 165185 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 165185 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 165185 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 165185 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 165185 in simple terms?

Why does HD 165185 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 165185?

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 165185.