astronomy

Gliese 806

Gliese 806 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 806 rather than just read about it. In short: Gliese 806 is a star in the northern constellation of Cygnus, located about a degree to the southeast of the bright star Deneb. It is invisible to the naked eye with an apparent visual magnitude of +10.79.

Key takeaways

Gliese 806 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 806 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Gliese 806 from memory before moving on to harder problems.

Reference excerpt

Gliese 806 is a star in the northern constellation of Cygnus, located about a degree to the southeast of the bright star Deneb. It is invisible to the naked eye with an apparent visual magnitude of +10.79. The star is located at a distance of 39.3 light years from the Sun based on stellar parallax. It is drifting closer with a radial velocity of −24.6 km/s, and is predicted to come to within 30.1 light-years in ~198,600 years. The star hosts two known planetary companions. The stellar classification of Gliese 806 is dM1.5, which indicates this is a small red dwarf star – an M-type main-sequence star that is generating energy through core hydrogen fusion. It is roughly three billion years old and is spinning with a projected rotational velocity of 0.46 km/s. The star has 42% of the mass and radius of the Sun. It is radiating 0.3% of the luminosity of the Sun from its photosphere at an effective temperature of 3,586 K.

Planetary system In 1989, Marcy and Benitz detected a periodicity of 416 days in radial velocity variation, inferring the possible presence of a companion with a mass of about 0.011 M☉. However, this candidate object was never confirmed. More recently, observations by TESS have found a candidate transiting planet with a period of less than a day. In January 2023, this planet was confirmed and a second, non-transiting planet found via radial velocity observations. A third radial velocity signal was also found, but the study was unable to confirm it as having a planetary origin. All known planets are super-Earths, and the inner transiting planet Gliese 806 b is likely to be rocky.

Worked examples

Example 1 — a first encounter with Gliese 806

Start with the simplest possible case. Write down what Gliese 806 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 806 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 806 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 806

In research: Gliese 806 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 806 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 806 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cygnus (constellation), Gliese and GJ objects, Hipparcos objects, so understanding it makes those chapters shorter.
In everyday life: Look for Gliese 806 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 806 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Gliese 806 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 806 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Gliese 806 in simple terms?

Why does Gliese 806 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 806?

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 806.