astronomy

HD 103197

HD 103197 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 103197 rather than just read about it. In short: HD 103197 is a star with a planetary companion in the southern constellation of Centaurus. It has an apparent visual magnitude of 9.40, which is too faint to be viewed with the naked eye.

Key takeaways

HD 103197 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 103197 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 103197 from memory before moving on to harder problems.

Reference excerpt

HD 103197 is a star with a planetary companion in the southern constellation of Centaurus. It has an apparent visual magnitude of 9.40, which is too faint to be viewed with the naked eye. Based on parallax measurements, HD 103197 is located at a distance of 187 light years from the Sun. It is drifting closer with a radial velocity of −4.6 km/s. This is a K-type main-sequence star with a stellar classification of K1V(p). In 1978, N. Houk noted that the cores of the star's H and K lines are weakly in emission; hence the 'p' code indicating a spectral peculiarity. The star is an estimated five billion years old with a projected rotational velocity of approximately 0.6 km/s and it appears to be very inactive. It has 90% of the mass and 95% of the radius of the Sun. Its metal content is five-eighths greater than in the Sun. In 2009, a gas giant exoplanet companion was discovered using the radial velocity method. This object is orbiting the host star at a distance of 0.249 AU (37.2 Gm) and a period of 47.84 d, with what is assumed to be a circular orbit.

Worked examples

Example 1 — a first encounter with HD 103197

Start with the simplest possible case. Write down what HD 103197 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 103197 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 103197 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 103197

In research: HD 103197 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 103197 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 103197 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Centaurus, Durchmusterung objects, Henry Draper Catalogue objects, so understanding it makes those chapters shorter.
In everyday life: Look for HD 103197 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 103197 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 103197 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 103197 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 103197 in simple terms?

HD 103197 is a star with a planetary companion in the southern constellation of Centaurus. It has an apparent visual magnitude of 9.40, which is too faint to be viewed with the naked eye.

Why does HD 103197 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 103197?

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 103197.