astronomy

HD 129899

HD 129899 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 129899 rather than just read about it. In short: HD 129899 (HIP 72670; 15 G. Apodis), is a solitary star located in the southern circumpolar constellation Apus, the bird-of-paradise.

Key takeaways

HD 129899 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 129899 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 129899 from memory before moving on to harder problems.

Reference excerpt

HD 129899 (HIP 72670; 15 G. Apodis), is a solitary star located in the southern circumpolar constellation Apus, the bird-of-paradise. It has an apparent magnitude of 6.44, placing it near the limit for naked eye visibility, even under ideal conditions. The object is located relatively far at a distance of 928 light-years based on Gaia DR3 parallax measurements and it is receding with a heliocentric radial velocity of 2.5 km/s. At its current distance, HD 129899's brightness is heavily diminished by an interstellar extinction of 0.55 magnitudes and it has an absolute bolometric magnitude of −1.28. HD 129899 has a stellar classification of ApSi, indicating that it is an Ap star with an overabundance of silicon in its spectrum. It has 3.43 times the mass of the Sun and 4.95 times the radius of the Sun. It radiates 190 times the luminosity of the Sun from its photosphere at an effective temperature of 10,617 K, giving it a bluish-white hue when viewed in the night sky. It has a near solar metallicity, having an iron abundance of [Fe/H] = −0.01 or 97.7% of the Sun's. At the age of 229 million years, HD 129899 has completed 95% of its main sequence lifetime. Unlike most chemically peculiar stars, HD 129899 spins rapidly with a rotational velocity of 199 km/s. The object was observed to be an Alpha2 Canum Venaticorum variable that fluctuates between 6.46 and 6.47 within 1.03 days, which corresponds to the period of the rotation. However, this has not been confirmed. HD 129899 has a relatively weak magnetic field of approximately 402±48 gauss.

References

Worked examples

Example 1 — a first encounter with HD 129899

Start with the simplest possible case. Write down what HD 129899 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 129899 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 129899 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 129899

In research: HD 129899 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 129899 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 129899 is common in secondary-school and first-year university syllabi. It links to neighbouring topics A-type main-sequence stars, Apus, Durchmusterung objects, so understanding it makes those chapters shorter.
In everyday life: Look for HD 129899 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 129899 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 129899 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 129899 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 129899 in simple terms?

HD 129899 (HIP 72670; 15 G. Apodis), is a solitary star located in the southern circumpolar constellation Apus, the bird-of-paradise.

Why does HD 129899 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 129899?

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 129899.