astronomy

IC 4687

IC 4687 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 IC 4687 rather than just read about it. In short: IC 4687 known as IRAS 18093-5744 or F18093-5744, is an Sb spiral galaxy located in the constellation of Pavo. It is located 250 million light years from Earth and was discovered by Royal Harwood Frost on August 1, 1904, who described the object "as brighter middle with magnitude of 14.

Key takeaways

IC 4687 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect IC 4687 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of IC 4687 from memory before moving on to harder problems.

Reference excerpt

IC 4687 known as IRAS 18093-5744 or F18093-5744, is an Sb spiral galaxy located in the constellation of Pavo. It is located 250 million light years from Earth and was discovered by Royal Harwood Frost on August 1, 1904, who described the object "as brighter middle with magnitude of 14. It has a surface brightness of 12.5.

Characteristics IC 4687 is classified as a luminous infrared galaxy. It has an infrared-luminosity of 1011.3 LΘ, compatible with a star formation rate of 30 MΘ yr−1. Through it has an energy output dominated by its star formation, the galaxy has a weak active galactic nucleus. The regions of IC 4687 are also known to contain high amounts of molecular gas surface densities of log ΣH2 (MΘ pc−2) = 2.9 ± 0.2. In additional, the galaxy is known to produce stars at a rapid rate when compared to normal star forming galaxies with the regions having log ΣSFR (MΘ yr−1 kpc−2) = 0.7 ± 0.4. This units are considered ~ 10 factor higher when compared to extreme values of nearby galaxies. Not to mention, IC 4687 has a velocity field mainly controlled by rotation. It also has a defined kinematic center that is synchronous with its nucleus. IC 4687 forms an interacting galaxy trio with two other galaxies, IC 4686 and IC 4689. Both of these galaxies are located ~ 10 and ~ 20 kiloparsecs away from IC 4687 and are classified as spiral-like with their velocity fields influenced by kinematic and rotation centers. Because of its close merger with IC 4686, a starburst and wolf-raynet galaxy, IC 4687 appears distorted. The Hubble images shows the galaxy has a distorted morphology with interstellar dust and gas apparently obscuring its companion. Not to mention, IC 4687 has large curly tidal tail as a result of the merger. It is possible the weak interaction from IC 4686 might triggered its starburst.

References

External links Media related to IC 4687 at Wikimedia Commons

IC 4687 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images IC 4687 at SIMBAD

Illustrations

Worked examples

Example 1 — a first encounter with IC 4687

Start with the simplest possible case. Write down what IC 4687 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 IC 4687 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 IC 4687 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 IC 4687

In research: IC 4687 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 IC 4687 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: IC 4687 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1904, Barred spiral galaxies, Discoveries by Royal Harwood Frost, so understanding it makes those chapters shorter.
In everyday life: Look for IC 4687 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 IC 4687 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what IC 4687 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 IC 4687 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is IC 4687 in simple terms?

Why does IC 4687 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 IC 4687?

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 IC 4687.