astronomy

Gliese 849

Gliese 849 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 849 rather than just read about it. In short: Gliese 849, or GJ 849, is a small, solitary star in the equatorial constellation of Aquarius. It has a reddish hue and is invisible to the naked eye with an apparent visual magnitude of 10.41.

Key takeaways

Gliese 849 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 849 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Gliese 849 from memory before moving on to harder problems.

Reference excerpt

Gliese 849, or GJ 849, is a small, solitary star in the equatorial constellation of Aquarius. It has a reddish hue and is invisible to the naked eye with an apparent visual magnitude of 10.41. The distance to this star is 28.8 light-years (8.8 parsecs) based on parallax, but it is drifting closer to the Sun with a radial velocity of −15.3 km/s. It has a pair of confirmed gas giant companions. The stellar classification of GJ 849 is M3.5V, which means this is a small red dwarf star generating energy through hydrogen fusion at its core region. Various studies have found super-solar abundances in the spectra, indicating that the elemental abundances of higher mass elements is significantly higher than in the Sun. The star has about half the mass and size of the Sun, and is spinning slowly with a rotation period of approximately 39 days. The estimated age of the star is more than three billion years. It is radiating a mere 2.9% of the luminosity of the Sun from its photosphere at an effective temperature of 3,490 K.

Planetary system In late 2006, a long-period Jupiter-like exoplanet was reported to be orbiting the red dwarf in a period just over 5 years in length. There was also a linear trend in the radial velocities which suggested another longer period companion. The trend in the radial velocities was confirmed in 2013. An orbit for the second exoplanet was finally determined in 2015. The first planet discovered, Gliese 849 b, was the first planet discovered orbiting a red dwarf with a semi-major axis greater than 0.21 AU.

See also List of star systems within 25–30 light-years Gliese 317 Gliese 649 Gliese 581 List of extrasolar planets

References

External links "Gj 849". Extrasolar Planets Encyclopaedia. Archived from the original on November 6, 2007. "BD-05 5715 / Gl 849". Solstation. Archived from the original on 2021-03-30. Retrieved 2007-05-26. "Image: Gliese 849". Aladin Previewer.

Worked examples

Example 1 — a first encounter with Gliese 849

Start with the simplest possible case. Write down what Gliese 849 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 849 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 849 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 849

In research: Gliese 849 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 849 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 849 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aquarius (constellation), Durchmusterung objects, Gliese and GJ objects, so understanding it makes those chapters shorter.
In everyday life: Look for Gliese 849 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 849 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Gliese 849 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 849 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Gliese 849 in simple terms?

Gliese 849, or GJ 849, is a small, solitary star in the equatorial constellation of Aquarius. It has a reddish hue and is invisible to the naked eye with an apparent visual magnitude of 10.41.

Why does Gliese 849 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 849?

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 849.