astronomy

Kepler-277b

Kepler-277b 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 Kepler-277b rather than just read about it. In short: Kepler-277b (also known by its Kepler Objects of Interest designation KOI-1215.01) is the second most massive and third-largest rocky planet ever discovered, with a mass close to that of Saturn. Discovered in 2014 by the Kepler Space Telescope, Kepler-277b is a sub-Neptune sized exoplanet with a very high mass and density for an object of its radius, suggesting a composition made mainly of rock and iron.

Key takeaways

Kepler-277b belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Kepler-277b to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Kepler-277b from memory before moving on to harder problems.

Reference excerpt

Kepler-277b (also known by its Kepler Objects of Interest designation KOI-1215.01) is the second most massive and third-largest rocky planet ever discovered, with a mass close to that of Saturn. Discovered in 2014 by the Kepler Space Telescope, Kepler-277b is a sub-Neptune sized exoplanet with a very high mass and density for an object of its radius, suggesting a composition made mainly of rock and iron. Along with its sister planet, Kepler-277c, the planet's mass was determined using transit-timing variations (TTVs).

Characteristics

Size and temperature Kepler-277b was detected using the transit method and TTVs, allowing for both its mass and radius to be determined to some level. It is approximately 2.92 R🜨, between the size of Earth and Neptune. At that radius, most planets should be gaseous Mini-Neptunes with no solid surface. However, the mass of Kepler-277b is extremely high for its size. Transit-timing variations indicate a planetary mass of about 87.3 M🜨, comparable to Saturn's mass at 95.16 M🜨. The planet has a density of approximately 19.3 g/cm3 and about 10.4 times the surface gravity of Earth. Such a high density for an object of this size implies that, like its sister planet, Kepler-277b is an enormous rock-based planet. It is currently the second most massive and third largest terrestrial planet ever discovered, behind Kepler-277c in radius and PSR J1719−1438 b in both radius and mass. Due to its proximity to its host star, Kepler-277b is quite hot with an equilibrium temperature of about 924 K (651 °C; 1,204 °F), hot enough to melt certain metals.

Internal structure and composition Models of Kepler-277b's internal structure suggest that it has a very large iron core with an estimated radius of 2.435 R🜨. The core predominantly consists of an allotrope of iron with a face-centered cubic (FCC) crystalline structure. At the innermost region of Kepler-277b's core where pressures reach as high as 37.52 terapascals, iron exists in a body-centered-tetragonal (BCT) and body-centered cubic (BCC) crystalline structure. Kepler-277b has a relatively thin silicate mantle in comparison to its core. The mantle of Kepler-277b is thought be predominantly composed of ultrahigh-pressure phases of magnesium silicates (MgSiO3). The uppermost mantle of Kepler-277b is thought to consist of olivine, wadsleyite, and ringwoodite while the lower part of Kepler-277b's upper mantle consists of silicate perovskite and post-perovskite.

Orbit Kepler-277b orbits close to its host star, with one orbit lasting 17.324 days. Its semi-major axis, or average distance from the parent object, is about 0.136 AU. For comparison, the planet Mercury in the Solar System takes 88 days to orbit at a distance of 0.38 AU. At this distance, Kepler-277b is very hot and most likely tidally locked to its host star. It is close to a 2:1 resonance with Kepler-277c, which orbits at an average distance of about 0.209 AU.

Host star

The parent star Kepler-277 is a large yellow star. It is 1.69 R☉ and 1.12 M☉, with a temperature of 5946 K, a metallicity of -0.315 [Fe/H], and an unknown age. For comparison, the Sun has a temperature of 5778 K, a metallicity of 0.00 [Fe/H], and an age of about 4.5 billion years. The large radius in comparison to its mass and temperature suggest that Kepler-277 could be a Subgiant star.

Worked examples

Example 1 — a first encounter with Kepler-277b

Start with the simplest possible case. Write down what Kepler-277b 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 Kepler-277b 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 Kepler-277b 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 Kepler-277b

In research: Kepler-277b 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 Kepler-277b 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: Kepler-277b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exoplanets discovered by the Kepler space telescope, Exoplanets discovered in 2014, Lyra, so understanding it makes those chapters shorter.
In everyday life: Look for Kepler-277b 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 Kepler-277b in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Kepler-277b 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 Kepler-277b out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Kepler-277b in simple terms?

Why does Kepler-277b 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 Kepler-277b?

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 Kepler-277b.