astronomy

HD 89890

HD 89890 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 89890 rather than just read about it. In short: HD 89890 is the brightest member of a multiple star system with at least four components, located in the southern constellation of Vela. It is visible to the naked eye with an apparent visual magnitude of 4.50.

Key takeaways

HD 89890 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 89890 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 89890 from memory before moving on to harder problems.

Reference excerpt

HD 89890 is the brightest member of a multiple star system with at least four components, located in the southern constellation of Vela. It is visible to the naked eye with an apparent visual magnitude of 4.50. The annual parallax shift of 2.6 mas provides a distance estimate of around 1,200 light-years (370 parsecs). It is moving further away from Earth with a heliocentric radial velocity of +10 km/s.

System

The Washington Double Star Catalog lists three visible components for this system. The brightest, component A, is of visual magnitude 4.50. Component B has a magnitude of 7.179, and as of 2000 lies at an angular separation of 7.10″ from A, along a position angle (PA) of 102°. Component C is a magnitude 9.125 star at a separation of 36.20″ from A at a PA of 191°. The physical link between the stars was described on the basis of their dynamic parallax and mean velocities. The three components A, B and C have Gaia Data Release 2 parallaxes of 2.6564±0.2314 mas, 2.1771±0.0490 mas, and 1.6097±0.0400 mas, respectively.

Properties In 1996, Christiaam Sterken et al. announced that HD 89890 is a variable star. It was given its variable star designation, MV Velorum, in 1997. Component A has a stellar classification of B3 III, and is categorized as a Be star. It shows photometric variations with multiple periods around 4.6 days and line-profile variations with a period of 2.318 days. The radial velocity of this star is constant. It has 10 times the Sun's radius and shines with 3,082 times the Sun's luminosity from its photosphere at an effective temperature of 15,000 K. The component B shows a variation in spectra consistent with being a double-lined spectroscopic binary. The brighter member (Ba) is a silicon star with a class of A0 IVpSi, while the fainter component (Bb) is of type A2. Component C has a class of K0 III, indicating it is an evolved giant star. The measured effective temperature of C is 5,500 K. The fact that component A most likely shares a common origin with C suggests that the former is much older than expected, and may actually be a blue straggler formed from the merger of a close binary. This could have been caused by the gravitational influence of an unseen companion of A.

References

Illustrations

Worked examples

Example 1 — a first encounter with HD 89890

Start with the simplest possible case. Write down what HD 89890 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 89890 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 89890 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 89890

In research: HD 89890 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 89890 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 89890 is common in secondary-school and first-year university syllabi. It links to neighbouring topics A-type main-sequence stars, A-type subgiants, Ap stars, so understanding it makes those chapters shorter.
In everyday life: Look for HD 89890 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 89890 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 89890 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 89890 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 89890 in simple terms?

Why does HD 89890 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 89890?

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 89890.