astronomy

NGC 2617

NGC 2617 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 2617 rather than just read about it. In short: NGC 2617 is a Seyfert galaxy in the equatorial constellation of Hydra. It was discovered on February 12, 1885, by French astronomer Édouard Stephan.

Key takeaways

NGC 2617 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 2617 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 2617 from memory before moving on to harder problems.

Reference excerpt

NGC 2617 is a Seyfert galaxy in the equatorial constellation of Hydra. It was discovered on February 12, 1885, by French astronomer Édouard Stephan. In 1888, Danish astronomer J. L. E. Dreyer described it as "extremely faint, very small, 2 very faint stars involved". It is located at an estimated distance of 202 million light years. In the infrared, the galaxy has an angular size of 0.693 by 0.652 arcminutes. This is an almost face-on spiral galaxy with a morphological classification of Sc, indicating a spiral galaxy (S) with loosely wound spiral arms (c). In 1992, NGC 2617 was shown to be an extragalactic source of X-ray emission, and in 1996 it was identified as a Seyfert 1.8 galaxy by E. C. Moran and associates. A radio counterpart was found in 1998. During April 2013, a dramatic outburst was discovered at the core of NGC 2617, and the spectral type was found to have changed to a Seyfert 1. An increase in X-ray emission was observed, followed by an increase in ultraviolet and then infrared luminosity. This event can be modeled by X-ray radiation heating the accretion disk orbiting a supermassive black hole (SMBH) at the center of the galaxy. This was followed by emission at longer wavelengths from the heated disk. An increase in luminosity between 2010 and 2012 may have cleared away dust in the inner part of the disk prior to the outburst, allowing a clearer view and changing the Seyfert type of the galaxy. The SMBH has an estimated mass of 30.9+11.8−8.5 million M☉. Additional outbursts were observed from 2016 to 2018, in between deep minima.

References

Illustrations

Worked examples

Example 1 — a first encounter with NGC 2617

Start with the simplest possible case. Write down what NGC 2617 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 2617 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 2617 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 2617

In research: NGC 2617 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 2617 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 2617 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Discoveries by Édouard Stephan, Hydra (constellation), NGC objects, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 2617 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 2617 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 2617 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 2617 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 2617 in simple terms?

NGC 2617 is a Seyfert galaxy in the equatorial constellation of Hydra. It was discovered on February 12, 1885, by French astronomer Édouard Stephan.

Why does NGC 2617 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 2617?

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 2617.