astronomy

LTT 3780

LTT 3780 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 LTT 3780 rather than just read about it. In short: LTT 3780, also known as TOI-732 or LP 729-54, is the brighter component of a wide visual binary star system in the constellation Hydra. This star is host to a pair of orbiting exoplanets.

Key takeaways

LTT 3780 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect LTT 3780 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of LTT 3780 from memory before moving on to harder problems.

Reference excerpt

LTT 3780, also known as TOI-732 or LP 729-54, is the brighter component of a wide visual binary star system in the constellation Hydra. This star is host to a pair of orbiting exoplanets. Based on parallax measurements, it is located at a distance of 72 light years from the Sun. LTT 3780 has an apparent visual magnitude of 13.07, requiring a telescope to view. The spectrum of LTT 3780 presents as a small M-type main-sequence star, a red dwarf, with a stellar classification of M3.5 V. It is spinning very slowly, with a rotation period of 104 days. The abundance of iron, an indicator of the star's metallicity, appears higher than in the Sun. The star is inactive, showing a negligible level of magnetic activity in its chromosphere. It has about 40% of the mass and 37% of the radius of the Sun. The star is radiating just 17% of the Sun's luminosity from its photosphere at an effective temperature of 3,331. Collectively designated LDS 3977, the two stars in this system share a common proper motion and have an angular separation of 15.8″, which corresponds to a (physical) projected separation of 348 AU. At this separation, the orbital period would be ~9,100 years. The fainter member is a red dwarf with a class of M5.0 V. It has 14% of the mass of the Sun and 17% of the Sun's radius.

Planetary system In 2020, an analysis carried out by a team of astronomers led by astronomer Ryan Cloutier of the TESS project confirmed the existence of two planets on mildly eccentric orbits, the inner being a super-Earth and the outer a small gas planet about half the mass of Uranus.

LTT 3780 b The inner planet, LTT 3780 b, is an ultra-short period rocky super-Earth. James Webb Space Telescope observations published in 2025 are consistent with the planet being a bare rock with no atmosphere; CO2 atmospheres with a surface pressure of at least 0.01 bar can be ruled out.

LTT 3780 c Astronomers utilizing the Gemini South 8.1-meter telescope performed an atmospheric survey of LTT 3780 c through high-resolution transmission spectroscopy. From observations during a single transit, they detected tentative signs of methane in the atmosphere but found no traces of ammonia, even though it is highly detectable in a cloud-free, hydrogen-rich atmosphere. A later study with JWST found stronger evidence for methane along with moderate to strong signs of either heavier hydrocarbons or sulfur-bearing molecules. This study also put constraints on the atmospheric abundance of water vapor, CO and CO2.

See also List of extrasolar planets List of multiplanetary systems

References

Worked examples

Example 1 — a first encounter with LTT 3780

Start with the simplest possible case. Write down what LTT 3780 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 LTT 3780 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 LTT 3780 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 LTT 3780

In research: LTT 3780 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 LTT 3780 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: LTT 3780 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Hydra (constellation), M-type main-sequence stars, Planetary systems with two confirmed planets, so understanding it makes those chapters shorter.
In everyday life: Look for LTT 3780 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 LTT 3780 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what LTT 3780 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 LTT 3780 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is LTT 3780 in simple terms?

LTT 3780, also known as TOI-732 or LP 729-54, is the brighter component of a wide visual binary star system in the constellation Hydra. This star is host to a pair of orbiting exoplanets.

Why does LTT 3780 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 LTT 3780?

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 LTT 3780.