astronomy

HD 102272

HD 102272 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 102272 rather than just read about it. In short: HD 102272 is a star in the equatorial constellation of Leo. With an apparent visual magnitude of 8.69, it is too faint to be visible to the naked eye.

Key takeaways

HD 102272 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 102272 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 102272 from memory before moving on to harder problems.

Reference excerpt

HD 102272 is a star in the equatorial constellation of Leo. With an apparent visual magnitude of 8.69, it is too faint to be visible to the naked eye. The star is located at a distance of approximately 1,140 light years based on parallax measurements, but is drifting closer to the Sun with a radial velocity of −12 km/s. As of 2008, two extrasolar planets are known to orbit the star. This is an evolved giant star with a stellar classification of K0. It is an estimated eight billion years old and has expanded to eight times the Sun's radius. The star has about the same mass as the Sun and is spinning with a projected rotational velocity of 2 km/s. It is radiating 25 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,750 K.

Planetary system In June 2008, the discovery of two extrasolar planets orbiting the star was announced. The planets were detected using the radial velocity method with the Hobby-Eberly Telescope. The radial velocity data clearly shows the presence of the inner planet (HD 102272 b). Although there is evidence for another planet, there is insufficient data to unambiguously determine its orbit. The pair are close to a 4:1 orbital resonance with the outer planet in a high eccentricity orbit.

Worked examples

Example 1 — a first encounter with HD 102272

Start with the simplest possible case. Write down what HD 102272 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 102272 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 102272 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 102272

In research: HD 102272 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 102272 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 102272 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Durchmusterung objects, Henry Draper Catalogue objects, Hipparcos objects, so understanding it makes those chapters shorter.
In everyday life: Look for HD 102272 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 102272 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 102272 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 102272 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 102272 in simple terms?

HD 102272 is a star in the equatorial constellation of Leo. With an apparent visual magnitude of 8.69, it is too faint to be visible to the naked eye.

Why does HD 102272 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 102272?

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 102272.