astronomy

HD 89345 b

HD 89345 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 89345 b rather than just read about it. In short: HD 89345 b is a Neptune-like exoplanet that orbits a G-type star. It is also called K2-234b.

Key takeaways

HD 89345 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 89345 b to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 89345 b from memory before moving on to harder problems.

Reference excerpt

HD 89345 b is a Neptune-like exoplanet that orbits a G-type star. It is also called K2-234b. Its mass is equivalent to 35.7 Earths, it takes 11.8 days to complete one orbit of its star, and is 0.105 AU away from its star. It was discovered by a team of 43 astrophysicists, one of which was V. Van Eylen, and was announced in 2018.

Overview The exoplanet HD 89345 b, which has a mass of 0.1 MJ and a radius of 0.61 RJ, was assigned to the class of ocean planets. The parent star of the planet, which is about 5.3 billion years old, belongs to the spectral class of G5V-G6V. It is 66 percent larger and 22 percent more massive than the Sun, and is located 413 light-years away. The effective temperature of the star is 5609 K. Considering that HD 89345 b makes one revolution around the star in 11.8 days at a distance of 0.11 AU, this planet was described by researchers as a warm subterranean with an equilibrium temperature of 1059 K.

Discovery HD 89345 b, a Saturn-sized exoplanet orbiting a slightly evolved star HD 89345, was discovered in 2018 using the transit photometry method, the process that detects distant planets by measuring the minute dimming of a star as an orbiting planet passes between it and the Earth. It is the only planet orbiting around HD 89345, a G5 class star, situated in the constellation of Leo in 413 light-years from the Sun. This star is aged 9.4 billion years. HD 89345 b orbits its star in about 12 terrestrial days in an elliptical orbit. The orbit is closer to the star than the inner limit of the habitable zone. It has a low density and can be composed of gas. Its parent star, HD 89345, is a bright star (apparent magnitude 9.3) observed by the K2 mission with one-minute time sampling. It exhibits solar-like oscillations. The data is collected by asteroseismology, which enables to determine the parameters of the star and find its mass and radius. Its mass is 1.12+0.04−0.01 M☉ and its mean radius is 1.657+0.020−0.004 R☉. The star appears to have recently left the main sequence, based on the inferred age, 9.4+0.4−1.3 Gyr, and the non-detection of mixed modes. The star hosts a "warm Saturn" with an orbital period of approximately 11.8 days and a radius of 6.86±0.14 R🜨. Radial-velocity follow-up observations performed with the FIES, HARPS, and HARPS-N spectrographs show that the planet has a mass of 35.7±3.3 M🜨. The data also show that the planet's orbit is eccentric ( e ≈ 0.2 {\displaystyle e\thickapprox 0.2} ).

See also List of potentially habitable exoplanets List of exoplanet firsts List of exoplanetary host stars List of exoplanets discovered using the Kepler spacecraft List of planets observed during Kepler's K2 mission List of nearest terrestrial exoplanet candidates

References

Worked examples

Example 1 — a first encounter with HD 89345 b

Start with the simplest possible case. Write down what HD 89345 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 89345 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 89345 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 89345 b

In research: HD 89345 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 89345 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 89345 b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exoplanets discovered in 2018, Leo (constellation), Transiting exoplanets, so understanding it makes those chapters shorter.
In everyday life: Look for HD 89345 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 89345 b in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 89345 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 89345 b out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 89345 b in simple terms?

HD 89345 b is a Neptune-like exoplanet that orbits a G-type star. It is also called K2-234b.

Why does HD 89345 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 89345 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 89345 b.