astronomy

HD 85390

HD 85390 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 85390 rather than just read about it. In short: HD 85390 is a star with an exoplanet companion in the southern constellation of Vela. It was given the proper name Natasha by Zambia during the 100th anniversary of the IAU.

Key takeaways

HD 85390 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 85390 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 85390 from memory before moving on to harder problems.

Reference excerpt

HD 85390 is a star with an exoplanet companion in the southern constellation of Vela. It was given the proper name Natasha by Zambia during the 100th anniversary of the IAU. Natasha means "thank you" in many languages of Zambia. This star is too faint to be seen with the naked eye, having an apparent visual magnitude of 8.54. It is located at a distance of 109 light-years from the Sun based on parallax, and is drifting further away with a radial velocity of 33 km/s. The stellar classification of HD 85390 is K1.5V, showing this to be a K-type main-sequence star. It is an older star with age estimates of 7–9 billion years, and is not considered chromospherically active. The star is spinning with a projected rotational velocity of 2 km/s. It is smaller, cooler, dimmer, and less massive than the Sun, but the metallicity is near solar.

Planetary system The planet HD 85390 b was detected by the radial velocity method in 2011. It is following an eccentric orbit at a distance of 1.4 AU from the host star. An additional planet in the system was suspected since 2013, only to be refuted in 2019.

References

Worked examples

Example 1 — a first encounter with HD 85390

Start with the simplest possible case. Write down what HD 85390 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 85390 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 85390 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 85390

In research: HD 85390 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 85390 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 85390 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 85390 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 85390 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 85390 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 85390 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 85390 in simple terms?

HD 85390 is a star with an exoplanet companion in the southern constellation of Vela. It was given the proper name Natasha by Zambia during the 100th anniversary of the IAU.

Why does HD 85390 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 85390?

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 85390.