astronomy

HD 129445

HD 129445 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 129445 rather than just read about it. In short: HD 129445 (HIP 72203; LTT 5856) is a star located in the southern constellation Circinus. It has an apparent magnitude of 8.80, making it faintly visible in binoculars but not to the naked eye.

Key takeaways

HD 129445 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 129445 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 129445 from memory before moving on to harder problems.

Reference excerpt

HD 129445 (HIP 72203; LTT 5856) is a star located in the southern constellation Circinus. It has an apparent magnitude of 8.80, making it faintly visible in binoculars but not to the naked eye. The object is located relatively close at a distance of 219 light-years based on Gaia DR3 parallax measurements but it is drifting away with a spectroscopic radial velocity of 8.56 km/s. It has an absolute magnitude of +4.73, which is similar to the Sun's absolute magnitude of 4.83.

Physical characteristics HD 129445 has a stellar classification of G6 V, indicating that it is an ordinary G-type main-sequence star like the Sun, albeit a bit cooler. It has 106% the mass of the Sun and 118% the radius of the Sun. It radiates 1.23 times the luminosity of the Sun from its photosphere at an effective temperature of 5,605 K, giving it a yellow hue when viewed in the night sky. HD 129445 is extremely metal enriched with an iron abundance more than twice of that of the Sun's and it spins slowly with a projected rotational velocity of 1.4 km/s. It is slightly older than the Sun at the age of 4.94 billion years.

Planetary system The star was observed by the Magellan Planet Search Program due to its absolute visual magnitude and high metallicity. The Magellan program conducted 17 doppler velocity measurements, which spans a full orbital period. The results led the program to detect a planet dubbed HD 129445 b. In 2023, the inclination and true mass of HD 129445 b were determined via astrometry.

See also HD 152079 HD 164604 HD 175167 HD 86226 List of extrasolar planets

References

Worked examples

Example 1 — a first encounter with HD 129445

Start with the simplest possible case. Write down what HD 129445 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 129445 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 129445 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 129445

In research: HD 129445 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 129445 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 129445 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Circinus, Durchmusterung objects, G-type main-sequence stars, so understanding it makes those chapters shorter.
In everyday life: Look for HD 129445 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “HD 129445” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study HD 129445 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 129445 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 129445 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 129445 in simple terms?

HD 129445 (HIP 72203; LTT 5856) is a star located in the southern constellation Circinus. It has an apparent magnitude of 8.80, making it faintly visible in binoculars but not to the naked eye.

Why does HD 129445 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 129445?

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 129445.