astronomy

NGC 2787

NGC 2787 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 2787 rather than just read about it. In short: NGC 2787 is a barred lenticular galaxy approximately 24 million light-years away in the northern constellation of Ursa Major. It was discovered on December 3, 1788 by German-born astronomer William Herschel.

Key takeaways

NGC 2787 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 2787 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 2787 from memory before moving on to harder problems.

Reference excerpt

NGC 2787 is a barred lenticular galaxy approximately 24 million light-years away in the northern constellation of Ursa Major. It was discovered on December 3, 1788 by German-born astronomer William Herschel. J. L. E. Dreyer described it as, "bright, pretty large, a little extended 90°, much brighter middle, mottled but not resolved, very small (faint) star involved to the southeast". The visible galaxy has an angular size of 2.5 × 1.5 arcminutes or 3.24 × 1.81 arcminutes and an apparent visual magnitude of 11.8. This galaxy is small and isolated with a morphological classification of SB(r)0+, which indicates a barred spiral (SB) with a ring around the bar (r). Being a lenticular galaxy, it has the large halo of an elliptical galaxy. The disk is inclined at an angle of 58°±3° to the line of sight from the Earth, with the major axis aligned along a position angle of 110°±3°. The galaxy has an unusually high mass-to-light ratio, much greater than for a typical spiral galaxy. The distribution of the galaxy's neutral hydrogen forms a clumpy ring with a radius of 10.3 kpc, double that of the visible galaxy, with a mass of 5.5×108 M☉. This ring appears misaligned with the central disk. NGC 2787 contains a low-ionization nuclear emission-line region (LINER) at its core, which is a type of region that is characterized by its spectral line emission from weakly ionized atoms. LINERs are very common within lenticular galaxies, with approximately one-fifth of nearby lenticular galaxies containing LINERs. The supermassive black hole at the center has a mass of 4.1+0.4−0.5×107 M☉. The central region of the galaxy contains dust rings that are tilted with respect to the disk, which may be the result of an encounter with another galaxy. NGC 2787 is part of the Ursa Major Cloud, which is part of the Virgo Supercluster.

References

External links Media related to NGC 2787 at Wikimedia Commons A Galaxy That's All Wound Up NGC 2787 at ESA/Hubble

Illustrations

Worked examples

Example 1 — a first encounter with NGC 2787

Start with the simplest possible case. Write down what NGC 2787 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 2787 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 2787 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 2787

In research: NGC 2787 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 2787 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 2787 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Barred lenticular galaxies, Field galaxies, LINER galaxies, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 2787 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 2787 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 2787 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 2787 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 2787 in simple terms?

Why does NGC 2787 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 2787?

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 2787.