astronomy

HD 92945

HD 92945 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 92945 rather than just read about it. In short: HD 92945 is a K-type main sequence star located 70 light years away in the northern constellation of Hydra. Its apparent visual magnitude varies by 0.02 magnitudes and is approximately 7.72 at maximum brightness.

Key takeaways

HD 92945 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 92945 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 92945 from memory before moving on to harder problems.

Reference excerpt

HD 92945 is a K-type main sequence star located 70 light years away in the northern constellation of Hydra. Its apparent visual magnitude varies by 0.02 magnitudes and is approximately 7.72 at maximum brightness.

Debris disk

In 2007, a debris disk with estimated dust mass 0.047±0.003 M🜨 has been observed around the star by coronagraphic imaging, using the ACS and NICMOS instruments on the Hubble Space Telescope. It appears to extend 45 to 175 astronomical units from HD 92945. The disk has a gap 20+10−8 AU wide at a radius of 73±3 AU, which may be being carved by a planet. No planet with mass exceeding 1-2 MJ was observed in the gap, but a lower-mass planet or a chain of two planets are still possible. Evidence for a planet via astrometric observations was presented in 2024. It could be explain the presence of the gap through long-term resonances with the disk, as its orbital separation is much less than the gap's radius and thus the planet would not be carving the disk directly. Alternatively, both the inner planet and an additional planet within the gap could be shepherding the disk through long-term gravitational interactions.

References

Illustrations

Worked examples

Example 1 — a first encounter with HD 92945

Start with the simplest possible case. Write down what HD 92945 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 92945 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 92945 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 92945

In research: HD 92945 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 92945 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 92945 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Circumstellar disks, Durchmusterung objects, Gliese and GJ objects, so understanding it makes those chapters shorter.
In everyday life: Look for HD 92945 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 92945 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 92945 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 92945 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 92945 in simple terms?

Why does HD 92945 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 92945?

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 92945.