astronomy

TOI-2109

TOI-2109 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-2109 rather than just read about it. In short: TOI-2109 is a magnitude 10.2 star in the constellation of Hercules. It is located 870 ly (268 pc) from Earth based on parallax measurements.

Key takeaways

TOI-2109 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-2109 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of TOI-2109 from memory before moving on to harder problems.

Reference excerpt

TOI-2109 is a magnitude 10.2 star in the constellation of Hercules. It is located 870 ly (268 pc) from Earth based on parallax measurements. This star is host to one confirmed exoplanet.

Characteristics TOI-2109 is an F-type main-sequence star, a star moderately larger, hotter and more luminous than the Sun that is fusing hydrogen into helium at its core. It is 1.7 times larger than the Sun, comparable to Sirius A, 1.4 times more massive and nearly five times brighter. The effective temperature of its surface is 6,530 K (6,260 °C; 11,290 °F), which is 10% hotter than the Sun, whose temperature measures 5,772 K (5,499 °C; 9,930 °F). The age of TOI-2109 is uncertain, around 1.8 billion years. The rotation period of this star is 14% longer than Earth's day, about 1/25th that of the Sun.

Planetary system

TOI-2109 hosts at least one exoplanet, which is named TOI-2109 b and was discovered in 2021 via the transit method. TOI-2109 b is a hot Jupiter, with the shortest orbital period of its class. It completes an orbit in just 0.67 days (16 hours), being separated by only 0.01791 astronomical units (2,679,000 km) from its host star. The extreme proximity also means TOI-2109 b is strongly irradiated. The dayside temperature measures 3,630 K (3,360 °C; 6,070 °F), while the nightside is around 1,000 degrees cooler, at less than 2,500 K (2,230 °C; 4,040 °F). Only 55 Cancri e and KELT-9b have hotter dayside temperatures. This planet is around 30% larger than Jupiter and five times more massive. Its orbit is well-aligned to the star's axis. In 2024, low-amplitude transit-timing variations were detected using the CHEOPS space telescope, which could be attributed to a yet unseen exoplanet. This putative planet should have an orbital period greater than 1.125 days and its other characteristics remain unconstrained.

Notes

References

Worked examples

Example 1 — a first encounter with TOI-2109

Start with the simplest possible case. Write down what TOI-2109 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-2109 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-2109 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-2109

In research: TOI-2109 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-2109 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-2109 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Durchmusterung objects, F-type main-sequence stars, Hercules (constellation), so understanding it makes those chapters shorter.
In everyday life: Look for TOI-2109 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-2109 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what TOI-2109 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-2109 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is TOI-2109 in simple terms?

TOI-2109 is a magnitude 10.2 star in the constellation of Hercules. It is located 870 ly (268 pc) from Earth based on parallax measurements.

Why does TOI-2109 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-2109?

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-2109.