astronomy

HD 131399 Ab

HD 131399 Ab 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 HD 131399 Ab rather than just read about it. In short: HD 131399 Ab (nicknamed Scorpion-1b) is a K-type or M-type main-sequence star located in the constellation of Centaurus which was mistaken for an exoplanet orbiting the quadruple-star system HD 131399. Characteristics The planet was thought to be about 16 million years old, with a mass of 4 (± 1) MJ (Jupiter masses), and a temperature of 850 K (577 °C; 1,070 °F) (± 50 K), which would make it one of the coldest and l…

Key takeaways

HD 131399 Ab belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect HD 131399 Ab to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 131399 Ab from memory before moving on to harder problems.

Reference excerpt

Characteristics The planet was thought to be about 16 million years old, with a mass of 4 (± 1) MJ (Jupiter masses), and a temperature of 850 K (577 °C; 1,070 °F) (± 50 K), which would make it one of the coldest and least massive directly imaged exoplanets. Its atmosphere was shown to contain both water and methane through the use of near-infrared spectroscopy (1.4–1.6 μm). Scientists believed it was unlikely that the planet harbored life due to it being gaseous. The planet was said to have "no liquid water, extremely powerful winds, and no surface; just below the uppermost layer of the atmosphere it rains liquid iron droplets." The central star HD 131399A is orbited by the less massive stars (HD 131399B and HD 131399C) at about 300 astronomical units (AU). HD 131399B and HD 131399C orbit each other at about 10 AU, while HD 131399 Ab was thought to orbit HD 131399A at about 80 AU. One orbit of HD 131399 Ab was thought to take 550 years. During about a quarter of the orbit, 100 to 140 years, all three suns would have been visible during a single day: during this period, any spot on the planet would be in perpetual sunlight—as the single sun sets, the binary pair rises.

Discovery HD 131399 Ab was discovered using the SPHERE imager of the Very Large Telescope at the European Southern Observatory, located in the Atacama Desert of Chile, and announced in a July 2016 paper in the journal Science. This would hae been the first exoplanet to be discovered by SPHERE and one of very few directly imaged exoplanets. The image was created from two separate SPHERE observations: one to image the three stars and one to detect the faint planet. After its discovery, the team unofficially named the system "Scorpion-1" and the planet "Scorpion-1b", after the survey that prompted its discovery, the Scorpion Planet Survey (principal investigator: Daniel Apai). In May 2017, observations collected with the Gemini Planet Imager, and including a reanalysis of the SPHERE data, suggested that this target is in fact a background star. Further observations in 2022 confirmed this.

Gallery

See also HD 188753 Ab YSES 2b, a red dwarf similarly mistaken to be a gaseous exoplanet

References

Illustrations

Worked examples

Example 1 — a first encounter with HD 131399 Ab

Start with the simplest possible case. Write down what HD 131399 Ab 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 HD 131399 Ab 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 HD 131399 Ab 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 HD 131399 Ab

In research: HD 131399 Ab 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 HD 131399 Ab 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: HD 131399 Ab is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 2016, Centaurus, Disproven exoplanets, so understanding it makes those chapters shorter.
In everyday life: Look for HD 131399 Ab 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 HD 131399 Ab in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 131399 Ab 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 HD 131399 Ab out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 131399 Ab in simple terms?

HD 131399 Ab (nicknamed Scorpion-1b) is a K-type or M-type main-sequence star located in the constellation of Centaurus which was mistaken for an exoplanet orbiting the quadruple-star system HD 131399. Characteristics The planet was thought to be about 16 million years old, with a mass of 4 (± 1) M…

Why does HD 131399 Ab 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 HD 131399 Ab?

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 HD 131399 Ab.