astronomy

NGC 2445

NGC 2445 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 2445 rather than just read about it. In short: NGC 2445 is a peculiar ring galaxy in the constellation Lynx. The galaxy lies about 200 million light years away from Earth, which means, given its apparent dimensions, that NGC 2445 is approximately 100,000 light years across.

Key takeaways

NGC 2445 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 2445 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 2445 from memory before moving on to harder problems.

Reference excerpt

NGC 2445 is a peculiar ring galaxy in the constellation Lynx. The galaxy lies about 200 million light years away from Earth, which means, given its apparent dimensions, that NGC 2445 is approximately 100,000 light years across. It was discovered by Édouard Stephan on January 18, 1877. The galaxy interacts with another galaxy, NGC 2444, and as a result its shape is distorted and new stars are formed.

Characteristics NGC 2445 is characterised by its distorted shape and star formation which is the result of the collision with another galaxy, NGC 2444. NGC 2444 has pulled gas away from NGC 2445 and as a result a bridge of young blue stars has formed between the two galaxies that gives the latter a triangular shape. The interaction has also created a ring of star clusters and HII regions around the nucleus. The kinematics of the gas indicate that the ring has an age of 60 ± 15 million years. When observed in radio waves the galaxy is asymmetric, with emission being from the nucleus, three star-forming regions and a ridge towards NGC 2444. The northwestern region appears to have stronger magnetic field than the other two. Two giant molecular clouds are visible in the 12CO(J=1–0) emission to the west and northwest of the nucleus. In mid infrared are visible some arms connecting the ring with the nucleus. The streamers between the two galaxies are among the first in what appears to be a wave of star formation that started on the galaxy's outskirts and continued inward. Researchers estimate the streamer stars were born between 50 million and 100 million years ago. The age of the star-forming knots in the ring is calculated to be 2–8 million years. Stars no older than one million to two million years old are forming closer to the centre of NGC 2445. Observations of carbon monoxide emission indicate that NGC 2445 still has abundant gas and star formation rates will increase. Hubble Space Telescope has uncovered dark filaments of gas in the starburst galaxy's bright core. Those features may have been formed by outbursts of material, however the dust from the outbursts blankets the nucleus in the visible spectrum. When observed in radio waves the core isn't very compact and its spectrum indicates the presence of a starburst region with an age between 1.5 and 5 million years. A shell of hydrogen gas measuring 20 kiloparsecs across has been found at a projected distance of about 100 kiloparsec of the galactic system. A filament of this shells points towards the galaxies indicating that it is a superbubble associated with them or a tidal tail.

Supernova One supernova has been observed in NGC 2444/5, SN 2016bam. The supernova occurred between the two galaxies, about 3.5 arcseconds away from a HII region of NGC 2445. It was a type II supernova which had magnitude 16.1 at discovery.

Nearby galaxies NGC 2445 and NGC 2444 (which lies about one arcminute away) form a pair, known as Arp 143. The pair is part of a galaxy group known as LGG 148. Other members of the group include the galaxies NGC 2476, NGC 2493, NGC 2524, NGC 2415, UGC 3937, and UGC 3944.

References

External links

NGC 2445 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images

Illustrations

Worked examples

Example 1 — a first encounter with NGC 2445

Start with the simplest possible case. Write down what NGC 2445 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 2445 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 2445 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 2445

In research: NGC 2445 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 2445 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 2445 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Arp objects, Astronomical objects discovered in 1877, Discoveries by Édouard Stephan, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 2445 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 NGC 2445 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 2445 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 2445 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 2445 in simple terms?

Why does NGC 2445 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 2445?

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 2445.