astronomy

HD 164922

HD 164922 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 164922 rather than just read about it. In short: HD 164922 is a seventh magnitude G-type main sequence star in the constellation of Hercules. To view it, binoculars or a telescope are necessary, as it is too faint to be visible to the naked eye.

Key takeaways

HD 164922 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 164922 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 164922 from memory before moving on to harder problems.

Reference excerpt

HD 164922 is a seventh magnitude G-type main sequence star in the constellation of Hercules. To view it, binoculars or a telescope are necessary, as it is too faint to be visible to the naked eye. It is 71.7 light-years (22.0 parsecs) distant from the Earth. It is reaching the end of its main sequence life and will soon evolve to become a red giant.

Nomenclature The name HD 164922 derives directly from the fact that the star is the 164,922nd star listed in the Henry Draper catalog. The designation b for its planet derives from the order of discovery. The designation of b is given to the first planet found orbiting a given star, followed by the other lowercase letters of the alphabet. In the case of HD 164922, only one was discovered, which was designated b, followed by three more planets, which were designated c, d, and e.

Stellar characteristics HD 164922 is a G-type main sequence star that is approximately 87% the mass of and 99% the radius of the Sun. It has a temperature of 5390 K and is about 10 billion years old, with estimates ranging as high as 13.4 billion years. In comparison, the Sun is about 4.6 billion years old and has a temperature of 5778 K. The star is metal-rich, with a metallicity ([Fe/H]) of 0.16, or 144% the solar amount. This is particularly odd for a star as old as HD 164922. Its luminosity (L☉) is 70% of the solar luminosity.

Planetary system On 15 July 2006, a long period Saturn-mass exoplanet was announced orbiting around HD 164922. This planet orbits at 2.11 AU from the star with a low eccentricity value of 0.05. Almost exactly ten years later in 2016, another exoplanet, though less massive than the first planet, was discovered orbiting farther in from the star. This planet has a minimum mass of nearly 13 times that of Earth, meaning it is possibly a Neptune-like planet. A third exoplanet, a hot super-Earth, was discovered in 2020, and a fourth, Neptune-mass, in 2021.

See also List of exoplanets discovered between 2000–2009 - HD 164922 b List of exoplanets discovered in 2016 - HD 164922 c List of exoplanets discovered in 2020 - HD 164922 d List of exoplanets discovered in 2021 - HD 164922 e

References

External links The Extrasolar Planet Encyclopedia: HD 164922 SIMBAD: HD 164922 "ARICNS: HD 164922". ARICNS. Centre of Astronomy, Heidelberg University.

Illustrations

Worked examples

Example 1 — a first encounter with HD 164922

Start with the simplest possible case. Write down what HD 164922 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 164922 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 164922 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 164922

In research: HD 164922 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 164922 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 164922 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Durchmusterung objects, G-type main-sequence stars, Gliese and GJ objects, so understanding it makes those chapters shorter.
In everyday life: Look for HD 164922 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 164922 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 164922 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 164922 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 164922 in simple terms?

HD 164922 is a seventh magnitude G-type main sequence star in the constellation of Hercules. To view it, binoculars or a telescope are necessary, as it is too faint to be visible to the naked eye.

Why does HD 164922 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 164922?

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 164922.