astronomy

NGC 3783

NGC 3783 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 3783 rather than just read about it. In short: NGC 3783 is a barred spiral galaxy located about 135 million light years away in the constellation Centaurus. Its velocity with respect to the cosmic microwave background is 3234 ± 22 km/s, which corresponds to a Hubble distance of 155.6 ± 10.9 Mly (47.70 ± 3.35 Mpc).

Key takeaways

NGC 3783 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 3783 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 3783 from memory before moving on to harder problems.

Reference excerpt

NGC 3783 is a barred spiral galaxy located about 135 million light years away in the constellation Centaurus. Its velocity with respect to the cosmic microwave background is 3234 ± 22 km/s, which corresponds to a Hubble distance of 155.6 ± 10.9 Mly (47.70 ± 3.35 Mpc). In addition, two non-redshift measurements give a distance of 155.74 ± 30.17 Mly (47.750 ± 9.250 Mpc). It was discovered by British astronomer John Herschel on 21 April 1835. NGC 3783 is inclined by an angle of 23° to the line of sight from the Earth along a position angle of about 163°. The morphological classification of SBa indicates a bar structure across the center (B) and tightly wound spiral arms (a). Although not shown by this classification, observers note the galaxy has a luminous inner ring surrounding the bar structure. The bright compact nucleus is active and categorized as a Seyfert 1 type. This nucleus is a strong source of X-ray emission and undergoes variations in emission across the electromagnetic spectrum.

The source of the activity in this galaxy is a rapidly rotating supermassive black hole, which is located at the core and is surrounded by an accretion disk of dust. The estimated mass of this black hole, from reverberation mapping, is about 2.8 million times the mass of the Sun. Interferometric observations yield an inner radius of 0.52 ± 0.16 ly (0.16 ± 0.05 pc) for the orbiting torus of dust. This is a member of a loose association of 47 galaxies known as the NGC 3783 group. Located at a mean distance of 117 million light-years (36 Mpc), the group is centered at coordinates α = 11h 37m 12s, δ = –37° 30′ 57.6″: equivalent to about 870×10^3 ly (267 kpc) from NGC 3783. The NGC 3783 group has a mean velocity of 2,903 ± 26 km/s with respect to the Sun and a velocity dispersion of 190 ± 24 km/s. The diffuse X-ray emission of the group is roughly centered on the galaxy NGC 3783. The NGC 3783 group is located in the Hydra-Antlia region of the Hydra-Centaurus Supercluster.

Gallery

References

External links Roy, Steve; et al. (May 25, 2000), "Chandra Clocks Million Mile Per Hour Wind Expanding From Vicinity of Giant Black Hole", Chandra Press Room, p. 13, Bibcode:2000cxo..pres...13., retrieved June 29, 2013 Hönig, Sebastian; et al. (June 20, 2013), "Dusty Surprise Around Giant Black Hole", European Southern Observatory, retrieved June 29, 2013

Illustrations

Worked examples

Example 1 — a first encounter with NGC 3783

Start with the simplest possible case. Write down what NGC 3783 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 3783 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 3783 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 3783

In research: NGC 3783 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 3783 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 3783 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1835, Barred spiral galaxies, Centaurus, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 3783 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 3783 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 3783 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 3783 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 3783 in simple terms?

Why does NGC 3783 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 3783?

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 3783.