astronomy

NGC 90

NGC 90 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 NGC 90 rather than just read about it. In short: NGC 90 is a grand-design spiral galaxy estimated to be about 333 million light years (102 megaparsecs) away in the constellation of Andromeda. The galaxy is currently interacting with NGC 93 and exhibits two highly elongated and distorted spiral arms.

Key takeaways

NGC 90 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect NGC 90 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 90 from memory before moving on to harder problems.

Reference excerpt

NGC 90 is a grand-design spiral galaxy estimated to be about 333 million light years (102 megaparsecs) away in the constellation of Andromeda. The galaxy is currently interacting with NGC 93 and exhibits two highly elongated and distorted spiral arms. These arms have bright blue star clusters which is indicative of star formation, likely caused by the interaction with its neighbor. NGC 90 and NGC 93 form the interacting galaxy pair Arp 65 in the Atlas of Peculiar Galaxies. Its interaction with NGC 93 has caused it produced characteristic similar to jellyfish galaxies such as tidal tails and escaping clouds of gas. It was discovered by R. J. Mitchell in 1854 and its apparent magnitude is 13.7.

Morphology NGC 90 is a grand-design spiral galaxy with two tidal arms extending from the main grand design arms. They are thin and long with one being aimed towards the northwest of the galaxy and a smoother, shorter one pointing in the opposite direction. These tidal tails straighten out towards the periphery.

Characteristics NGC 90 is interacting with another spiral galaxy located 64 kiloparsecs away, known as NGC 93, together forming Arp 65. A interaction with NGC 93 occurred roughly 100-250 million years ago displacing a large amount of gas far beyond its main disk. This interaction has caused two tidal tails extending from the galaxy. Along the western tidal tail and east of the disk, there are several regions of star formation outside the main disk of the galaxy. Evidence for this can be seen with images of bright blue regions which is indicative of star formation regions and populations of young stars. The central regions of the galaxy is affected by photoionization creating shocks.

Cloud Perhaps the most interesting thing about NGC 90 is its large H I cloud located southeast of the galaxy. This cloud has a mass of 6.8 × 109 solar masses meaning that this cloud contains about half of the galaxies total gas content in terms of mass. It is being displaced outwards from the galaxy traveling at a velocity of around 340 km/s. At velocities this high, it is not gravitationally bounded to NGC 90. The cause of this cloud and its speed is likely due to forces of ram pressure stripping being applied to NGC 90 as it travels through the hot gas of the galaxy group. This means that NGC 90 could be a potential jellyfish galaxy. Another factor influencing the loss of gas in NGC 90 is the interaction with the more gas-rich companion. H I clouds were only marginally detected in the main galaxy. The clouds that were detected has an asymmetric morphology.

References

Illustrations

Worked examples

Example 1 — a first encounter with NGC 90

Start with the simplest possible case. Write down what NGC 90 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 NGC 90 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 NGC 90 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 NGC 90

In research: NGC 90 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 NGC 90 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: NGC 90 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Andromeda (constellation), Arp objects, Astronomical objects discovered in 1854, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 90 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.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study NGC 90 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 90 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 NGC 90 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 90 in simple terms?

Why does NGC 90 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 NGC 90?

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 NGC 90.