astronomy

L 168-9

L 168-9 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 L 168-9 rather than just read about it. In short: L 168-9 (also known as GJ 4332 or TOI-134, officially named Danfeng) is a red dwarf star located 82.1 light-years (25.2 parsecs) away from the Solar System in the constellation of Tucana. The star has about 61% the mass and 60% the radius of the Sun.

Key takeaways

L 168-9 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect L 168-9 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of L 168-9 from memory before moving on to harder problems.

Reference excerpt

L 168-9 (also known as GJ 4332 or TOI-134, officially named Danfeng) is a red dwarf star located 82.1 light-years (25.2 parsecs) away from the Solar System in the constellation of Tucana. The star has about 61% the mass and 60% the radius of the Sun. It has a temperature of 3,842 K (3,569 °C; 6,456 °F) and a rotation period of 29 days. L 168-9 is orbited by one known exoplanet.

Nomenclature The designation L 168-9 comes from Luyten's first catalogue of stars with high proper motion. In August 2022, this planetary system was included among 20 systems to be named by the third NameExoWorlds project. The approved names, proposed by a team from China, were announced in June 2023. L 168-9 is named Danfeng (丹凤) and its planet is named Qingluan (青鸾), after mythological birds of ancient China.

Planetary system The exoplanet L 168-9 b, officially named Qingluan, was discovered in 2020 using TESS. At the discovery, this terrestrial super-Earth was thought to have about 4.6 times the mass and 1.39 times the radius of Earth, and an estimated equilibrium temperature of 965 K (692 °C; 1,277 °F). L 168-9 b is a target for observation and atmospheric characterization with the James Webb Space Telescope, and has been observed as one of its first targets. A newer study refined the planetary parameters of L 168-9 b. The newer research found a lower mass of 4.07 M🜨 and a higher radius of 1.63 R🜨. These parameters imply a lower density of 5.18 g/cm3, in contrast to the previous value of 9.6 g/cm3. Given the lower density of the planet, it more likely has a pure rock composition, rather than a 50% iron core and 50% silicate mantle as previously proposed. The orbital parameters show little variation, while the equilibrium temperature was updated to 998±39 K. Transmission spectra of combined near- and mid-infrared observations by the James Webb Space Telescope showed no atmospheric features. However, further observations are required to rule out a thick (100 bar) carbon dioxide atmosphere, which could also explain the data.

References

Worked examples

Example 1 — a first encounter with L 168-9

Start with the simplest possible case. Write down what L 168-9 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 L 168-9 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 L 168-9 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 L 168-9

In research: L 168-9 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 L 168-9 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: L 168-9 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Durchmusterung objects, Gliese and GJ objects, Hipparcos objects, so understanding it makes those chapters shorter.
In everyday life: Look for L 168-9 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.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study L 168-9 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what L 168-9 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 L 168-9 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is L 168-9 in simple terms?

Why does L 168-9 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 L 168-9?

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 L 168-9.