astronomy

GJ 3470 b

GJ 3470 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 GJ 3470 b rather than just read about it. In short: GJ 3470 b (occasionally Gliese 3470 b, formally named Phailinsiam) is an exoplanet orbiting the star GJ 3470, located in the constellation Cancer. With a mass of just under 14 Earth-masses, a radius approximately 4.3 times that of Earth's, and a high equilibrium temperature of 673 K (400 °C; 752 °F), it is a hot Neptune.

Key takeaways

GJ 3470 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 GJ 3470 b to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of GJ 3470 b from memory before moving on to harder problems.

Reference excerpt

GJ 3470 b (occasionally Gliese 3470 b, formally named Phailinsiam) is an exoplanet orbiting the star GJ 3470, located in the constellation Cancer. With a mass of just under 14 Earth-masses, a radius approximately 4.3 times that of Earth's, and a high equilibrium temperature of 673 K (400 °C; 752 °F), it is a hot Neptune. The orbit of GJ 3470 b is strongly inclined to the equatorial plane of the parent star, with misalignment equal to 97+16−11°.

Nomenclature In August 2022, this planet and its host star were included among 20 systems to be named by the third NameExoWorlds project. The approved names, proposed by a team from Thailand, were announced in June 2023. GJ 3470 b is named Phailinsiam and its host star is named Kaewkosin, after the "Siamese Sapphire" and the crystals of Indra in Thai.

Atmosphere The atmosphere of Phailinsiam is one of the best spectroscopically characterized among all exoplanets. The exoplanet's atmosphere was first observed by researchers Akihiko Fukui, Norio Narita and Kenji Kuroda at the University of Tokyo in 2013, and afterwards, Fukui commented, "Suppose the atmosphere consists of hydrogen and helium, the mass of the atmosphere would be 5–20% of the total mass of the planet. Comparing that to the fact that the mass of Earth's atmosphere is about one ten-thousandth of a percent (0.0001%) of the total mass of the Earth, this planet has a considerably thick atmosphere." In 2013, by means of Large Binocular Telescope observations, with the LBC Blue and Red cameras, a team reported the detection of Rayleigh scattering in the atmosphere of this planet. In 2015 a team using the Las Cumbres Observatory Global Telescope (LCOGT) network confirmed this finding. In the Las Cumbres researchers' paper published in The Astrophysical Journal, they conclude that the most plausible explanation for the scattering effect to be an atmosphere made predominantly of hydrogen and helium, causing the exoplanet to be veiled by dense clouds and hazes. It is thought that the planet would appear blue to the human eye due to this scattering. In 2017–2019, the primary hydrogen atmosphere with overall low metallicity, depleted methane and traces of water was characterized. It is likely filling an entire Roche lobe of the planet. In 2019 and 2020, a metastable helium outflow was detected in the atmosphere of Phailinsiam, indicating the atmosphere is currently escaping at a rate of 30,000-100,000 tons per second, or 0.16-0.53 Earth masses per billion years. In 2024, a team of astronomers led by Thomas Beatty discovered a haze of sulfur dioxide (SO2) in the atmosphere of the exoplanet using JWST observations, indicating active chemical reactions in the atmosphere, likely triggered by radiation from its nearby star. These same observations also clearly measured the presence of methane and carbon dioxide in the atmosphere for the first time, and confirmed that the planet has a high metallicity-atmosphere. These observations also showed that previous claims of Mie-scattering clouds were false.

Gallery

Illustrations

Worked examples

Example 1 — a first encounter with GJ 3470 b

Start with the simplest possible case. Write down what GJ 3470 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 GJ 3470 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 GJ 3470 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 GJ 3470 b

In research: GJ 3470 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 GJ 3470 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: GJ 3470 b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cancer (constellation), Exoplanets detected by radial velocity, Exoplanets discovered in 2012, so understanding it makes those chapters shorter.
In everyday life: Look for GJ 3470 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 GJ 3470 b in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what GJ 3470 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 GJ 3470 b out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is GJ 3470 b in simple terms?

Why does GJ 3470 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 GJ 3470 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 GJ 3470 b.