astronomy

Gliese 15 Ac

Gliese 15 Ac 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 Gliese 15 Ac rather than just read about it. In short: Gliese 15 Ac (also known as Groombridge 34 Ac, GX Andromedae c) is an exoplanet orbiting the nearby red dwarf star Gliese 15 A (Groombridge 34 A, GX Andromedae), which is part of a binary star system located about 11.6 light-years from the Sun. The planet was first proposed in October 2017 using radial velocity data from the CARMENES spectrograph, combined with measurements from the HARPS and HIRES spectrographs, an…

Key takeaways

Gliese 15 Ac belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Gliese 15 Ac to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Gliese 15 Ac from memory before moving on to harder problems.

Reference excerpt

Gliese 15 Ac (also known as Groombridge 34 Ac, GX Andromedae c) is an exoplanet orbiting the nearby red dwarf star Gliese 15 A (Groombridge 34 A, GX Andromedae), which is part of a binary star system located about 11.6 light-years from the Sun. The planet was first proposed in October 2017 using radial velocity data from the CARMENES spectrograph, combined with measurements from the HARPS and HIRES spectrographs, and its existence was confirmed in April 2018 using HARPS-N data. It has a minimum mass 36 times that of Earth and orbits at around 5.4 astronomical units with a period of 7,600 days (21 years), an orbit which may have been sculpted by interaction with the companion star, Gliese 15 B. As of 2020, Gliese 15 Ac is the longest-period sub-Jovian planet discovered by radial velocity.

References

Illustrations

Worked examples

Example 1 — a first encounter with Gliese 15 Ac

Start with the simplest possible case. Write down what Gliese 15 Ac 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 Gliese 15 Ac 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 Gliese 15 Ac 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 Gliese 15 Ac

In research: Gliese 15 Ac 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 Gliese 15 Ac 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: Gliese 15 Ac is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exoplanet stubs, Exoplanets detected by radial velocity, Exoplanets discovered in 2018, so understanding it makes those chapters shorter.
In everyday life: Look for Gliese 15 Ac 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 Gliese 15 Ac in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Gliese 15 Ac 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 Gliese 15 Ac out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Gliese 15 Ac in simple terms?

Why does Gliese 15 Ac 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 Gliese 15 Ac?

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 Gliese 15 Ac.