astronomy

Luyten b

Luyten b 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 Luyten b rather than just read about it. In short: Luyten's Star b (GJ 273 b) is a confirmed exoplanet, likely rocky, orbiting within the habitable zone of the nearby red dwarf Luyten's Star. It is the fourth-closest potentially habitable exoplanet known, at a distance of 12 light-years.

Key takeaways

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

Reference excerpt

Luyten's Star b (GJ 273 b) is a confirmed exoplanet, likely rocky, orbiting within the habitable zone of the nearby red dwarf Luyten's Star. It is the fourth-closest potentially habitable exoplanet known, at a distance of 12 light-years. Only Proxima Centauri b, Ross 128 b, and GJ 1061 d are closer. Discovered alongside Gliese 273c in June 2017, Luyten b is a super-Earth of around 2.89 times the mass of Earth and receives only 6% more starlight than Earth, making it one of the best candidates for habitability.

Characteristics

Mass, radius, and temperature

Mass and size Luyten b is a super-Earth, meaning that it has a mass and/or radius greater than that of Earth, but less than that of Uranus or Neptune. Radial velocity measurements shows that the planet has a minimum mass of 2.89 M🜨, placing it at the lower end of the super-Earth range. The planet has not been found to transit its star, and as a result its true mass and radius are not known. Due to its low mass, the planet is likely terrestrial, with a predicted radius of 1.51 R🜨. Up to four candidate planets have been proposed around Luyten's Star. A 2020 study showed that if all four planets are present, their true masses must be close to their minimum masses for the system to be stable, with an upper limit of 3.03 M🜨 for Luyten b.

Temperature The planet receives an incident flux only 6% greater than that of Earth. With an estimated albedo, or proportion of light reflected by the planet, of 0.30, Luyten b has an equilibrium temperature of 259 K. For comparison, Earth has an equilibrium temperature of 255 K. With an Earth-like atmosphere — if it has one — Luyten b would have an average surface temperature of about 292 K (19 °C; 66 °F), very similar to that of Earth.

Orbit and rotation Luyten b orbits quite close to its host star. One full revolution around Luyten's Star takes about 18.6 days at an average distance of 0.091 AU, much closer in than Mercury, which has a year of 88 days and an orbital radius of 0.387 AU. However, because the host star is so dim, Luyten b falls right within the system's habitable zone and only receives 6% more starlight than Earth. Luyten b has a moderate orbital eccentricity of 0.10 ± 0.08.

Host star Luyten's Star is a medium-sized red dwarf star on the main sequence. It has 29.3% the radius, 29% the mass, 0.88% the luminosity of the Sun, and has an effective temperature of 3,382 K. Unlike many nearby red dwarfs, like Proxima Centauri, Luyten's Star is very inactive with a long rotation period of over 118 days.

Active SETI In October 2017 and 2018, the nonprofit organization METI (Messaging Extraterrestrial Intelligence) sent a message, "Sónar Calling GJ273b", containing dozens of short musical compositions and a scientific "tutorial" towards the planet in hopes of contacting any potential extraterrestrial civilizations.

See also LHS 1140 b, a massive habitable zone Super-Earth around another quiet star List of potentially habitable exoplanets Proxima Centauri b, the closest potentially habitable exoplanet to Earth Ross 128 b, the second-closest habitable zone planet and very similar to Proxima b

References

Worked examples

Example 1 — a first encounter with Luyten b

Start with the simplest possible case. Write down what Luyten b 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 Luyten b 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 Luyten b 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 Luyten b

In research: Luyten b 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 Luyten b 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: Luyten b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Canis Minor, Exoplanets discovered in 2017, Super-Earths in the habitable zone, so understanding it makes those chapters shorter.
In everyday life: Look for Luyten b 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 Luyten b in 20 minutes

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

Frequently asked questions

What is Luyten b in simple terms?

Why does Luyten b 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 Luyten b?

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 Luyten b.