astronomy

HD 164922 b

HD 164922 b 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 b rather than just read about it. In short: HD 164922 b is an exoplanet orbiting the star HD 164922 about 72 light-years from Earth in the constellation Hercules. Its inclination is not known, and its true mass may be significantly greater than the radial velocity lower limit of 0.36 Jupiter masses.

Key takeaways

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

Reference excerpt

HD 164922 b is an exoplanet orbiting the star HD 164922 about 72 light-years from Earth in the constellation Hercules. Its inclination is not known, and its true mass may be significantly greater than the radial velocity lower limit of 0.36 Jupiter masses. The planet also has a low eccentricity of 0.05, about the same as Jupiter and Saturn in the Solar System. The exoplanet was found by using the radial velocity method, from radial-velocity measurements via observation of Doppler shifts in the spectrum of the planet's parent star.

Characteristics

Mass, radius and temperature HD 164922 b is a gas giant, an exoplanet that has a radius and mass around that of the planets Jupiter and Saturn. It has a temperature of 159 K (−114 °C; −173 °F). It has an estimated mass of around 0.36 MJ, and a potential radius of around 8 R🜨 based on its similar mass to Saturn.

Host star

The planet orbits a (G-type) star named HD 164922. The star has a mass of 0.87 M☉ and a radius of around 0.99 R☉. It has a temperature of 5293 K and is 13.4 billion years old. 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. The star's apparent magnitude, or how bright it appears from Earth's perspective, is 7.01. Therefore, HD 164922 is too dim to be seen with the naked eye, but can be viewed using good binoculars.

Orbit HD 164922 b orbits its star every 1,155 days at a distance of 2.1 AU (compared to Mars's orbital distance from the Sun, which is around 1.5 AU). It receives only 15% of the sunlight as the Earth does from the Sun.

Discovery The search for HD 164922 b started when its host star was chosen an ideal target for a planet search using the radial velocity method (in which the gravitational pull of a planet on its star is measured by observing the resulting Doppler shift), as stellar activity would not overly mask or mimic Doppler spectroscopy measurements. It was also confirmed that HD 164922 is neither a binary star nor a quickly rotating star, common false positives when searching for transiting planets. Analysis of the resulting data found that the radial velocity variations most likely indicated the existence of a planet. The net result was an estimate of a 12.9 M🜨 planetary companion orbiting the star at a distance of 0.33 AU with an eccentricity of 0.07. The discovery of HD 164922 b was reported in the online archive arXiv on June 30, 2016.

See also 14 Herculis b List of exoplanets discovered between 2000–2009

References

Worked examples

Example 1 — a first encounter with HD 164922 b

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

In research: HD 164922 b 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 b 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 b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exoplanets detected by radial velocity, Exoplanets discovered in 2006, Giant planets, so understanding it makes those chapters shorter.
In everyday life: Look for HD 164922 b 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 b in 20 minutes

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

Frequently asked questions

What is HD 164922 b in simple terms?

Why does HD 164922 b 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 b?

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 b.