astronomy

HD 145457

HD 145457 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 145457 rather than just read about it. In short: HD 145457 is a star located in the northern constellation of Corona Borealis (The Northern Crown) at a distance of around 442 light-years from the Sun, as determined through parallax measurements. It has been formally named Kamuy by the IAU, after a spiritual or divine being in Ainu mythology.

Key takeaways

HD 145457 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 145457 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 145457 from memory before moving on to harder problems.

Reference excerpt

HD 145457 is a star located in the northern constellation of Corona Borealis (The Northern Crown) at a distance of around 442 light-years from the Sun, as determined through parallax measurements. It has been formally named Kamuy by the IAU, after a spiritual or divine being in Ainu mythology. With an apparent magnitude of 6.57, it is barely visible to the unaided eye on dark nights clear of light pollution. It is drifting closer to the Sun with a radial velocity of −3.2 km/s. HD 145457 is an aging giant star with a stellar classification of K0 III that has cooled and expanded off the main sequence after exhausting its core hydrogen supply. With the assumption that it is a helium-burning object, the properties of HD 145457 can be derived by comparison with evolutionary tracks. With an age of 5.2 billion years old, it is around 1.57 times as massive as the Sun and has swollen to around 10 times its diameter. It is radiating 50 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,738 K. It is a lithium-rich giant, unusual since lithium is rapidly destroyed once a star becomes a red giant. One explanation for the excess lithium in these stars has been a recent engulfment of a planet, but it is now thought more likely to be due to nucleosynthesis in the star. It is generally assumed that these lithium-rich giants are members of the red clump, core helium burning stars at the cool end of the horizontal branch.

Planetary system HD 145457 has an exoplanetary companion called HD 145457 b discovered in 2010. 2.9 times as massive as Jupiter, it orbits about every 176 days with an orbital eccentricity of 0.112±3.1. Its semimajor axis is 0.76 AU. HD 145457 b was discovered by precise Doppler measurements with the Subaru Telescope. As part of the IAU NameExoWorlds project in 2019, HD 145457 b has been formally named Chura. The name was selected by Japan. Chura is a word in the Ryukyuan/Okinawan language meaning natural beauty.

References

Worked examples

Example 1 — a first encounter with HD 145457

Start with the simplest possible case. Write down what HD 145457 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 145457 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 145457 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 145457

In research: HD 145457 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 145457 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 145457 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Corona Borealis, Durchmusterung objects, Henry Draper Catalogue objects, so understanding it makes those chapters shorter.
In everyday life: Look for HD 145457 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 145457” →

Affiliate

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

How to study HD 145457 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 145457 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 145457 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 145457 in simple terms?

Why does HD 145457 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 145457?

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 145457.