astronomy

TOI-2431 b

TOI-2431 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 TOI-2431 b rather than just read about it. In short: TOI-2431 b is an extrasolar planet orbiting the orange dwarf star TOI-2431. It was initially detected by the transit method in 2019, and with additional observations was confirmed in 2025.

Key takeaways

TOI-2431 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 TOI-2431 b to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of TOI-2431 b from memory before moving on to harder problems.

Reference excerpt

TOI-2431 b is an extrasolar planet orbiting the orange dwarf star TOI-2431. It was initially detected by the transit method in 2019, and with additional observations was confirmed in 2025. The planet is notable for its extremely short orbital period of 5h 22min, one of the shortest known. In about 31 million years, it will enter the Roche lobe of the host star and be torn apart.

Characteristics TOI-2431 b has around 1.54 times Earth's radius (R🜨) and 6.2 times Earth's mass (M🜨), resulting in a density of 9.2 g/cm3, which is significantly higher than that of Earth and implies a rocky composition. Its orbital period is extremely short, at just 0.224 days (5.4 hours), the sixth-shortest for any known exoplanet, as of 2025. The separation from the host star is 0.0063 astronomical units (940,000 kilometres), a constant value throughout the orbit, since its eccentricity is roughly zero. The separation is just 30% wider than the Roche lobe of the host star, and is decaying (shortening) at a rate that implies a remaining lifetime of about 31 million years before the planet enters the star's Roche lobe and is torn apart. This close orbit implies TOI-2431 b is tidally locked, with one side permanently facing the host star and the other side always facing it. It also implies a high irradiation, and hence a high temperature. Its equilibrium temperature is estimated at 2,063 K (1,790 °C), assuming a Bond albedo of 0. The elevated temperature imply its dayside is likely made up from molten lava. Rocky planets at such orbital periods and high irradiances are expected to have an atmosphere made up from vapors of rock in the side always facing the host star. Such atmosphere can be detected with transmission spectroscopy using powerful telescopes such as the James Webb Space Telescope. Since TOI-2431 has a relatively bright apparent magnitude, TOI-2431 b has a high potential for the detection of such an atmosphere.

Discovery The planet was initially detected as a candidate in 2019 by the Transiting Exoplanet Survey Satellite and while a candidate, was briefly mentioned in a 2021 HST proposal and a 2022 study about the detection of an evaporating atmosphere made of rock vapor, owing its short orbital period and the feasibility of such a detection. It was confirmed in 2025 by Kaya Han Tas et al, using a joint of Transit photometry from the TESS and Doppler spectroscopy from the NEID and Habitable-zone Planet Finder (HPF) spectrographs, as well as imaging to secure the accuracy of the observations by ruling out potential artifacts from stars within field of view of the equipments.

Host star TOI-2431 (HIP 11707) is a K-type main-sequence star located in the constellation of Cetus. It is somewhat nearby to the Solar System, at a distance of 117.4 light-years (36.0 parsecs). The star has 0.66 times the mass of the Sun and 0.651 times the Sun's radius. It irradiates 10.9% of the Sun's luminosity from its photosphere at an effective temperature of 4,109 K, giving it an orange hue typical of K-type stars. The spectral type is K7V, the same of 61 Cygni B. Its apparent magnitude of 10.89 is below the threshold for naked eye vision.

See also M62H b and PSR J1719−1438 b, exoplanets with the shortest known orbits. K2-137b

References

Worked examples

Example 1 — a first encounter with TOI-2431 b

Start with the simplest possible case. Write down what TOI-2431 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 TOI-2431 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 TOI-2431 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 TOI-2431 b

In research: TOI-2431 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 TOI-2431 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: TOI-2431 b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exoplanets discovered by TESS, Exoplanets discovered in 2025, Transiting exoplanets, so understanding it makes those chapters shorter.
In everyday life: Look for TOI-2431 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 TOI-2431 b in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what TOI-2431 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 TOI-2431 b out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is TOI-2431 b in simple terms?

TOI-2431 b is an extrasolar planet orbiting the orange dwarf star TOI-2431. It was initially detected by the transit method in 2019, and with additional observations was confirmed in 2025.

Why does TOI-2431 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 TOI-2431 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 TOI-2431 b.