astronomy

NGC 4253

NGC 4253 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 4253 rather than just read about it. In short: NGC 4253 is a barred spiral galaxy located in the constellation Coma Berenices. It is located at a distance of about 185 million light years from Earth, which, given its apparent dimensions, means that NGC 4253 is about 65,000 light years across.

Key takeaways

NGC 4253 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 4253 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 4253 from memory before moving on to harder problems.

Reference excerpt

NGC 4253 is a barred spiral galaxy located in the constellation Coma Berenices. It is located at a distance of about 185 million light years from Earth, which, given its apparent dimensions, means that NGC 4253 is about 65,000 light years across. It was discovered by William Herschel on February 3, 1788. It is a Seyfert galaxy.

Characteristics The NGC 4253 is a barred galaxy with thick bar, while the arms form a ring. Marquez et al. suggested that the galaxy has a secondary bar perpendicular to the main bar, although that could be an artifact due to the presence of strong dust lanes and no inner bar is visible in images by WFPC2 F606W of the Hubble Space Telescope. There is evidence of star formation along the dust lanes in the leading edge of the bar, especially at the east half. The nucleus of NGC 4253 has been found to be active and it has been categorised as a narrow line type I Seyfert galaxy. The most accepted theory for the energy source of active galactic nuclei is the presence of an accretion disk around a supermassive black hole. The mass of the black hole in the centre of NGC 5506 is estimated to be 1–13 × 106 M☉ based on reverberation mapping of the hydrogen lines, 1.6+1.4−1.2×106 M☉ based on time lag spectra, and 1.26+1.00−0.77×106 M☉ based on X-ray variations. The nucleus emits X-rays. The X-rays have been found to vary in intensity, exhibiting quasi-periodic oscillation, although this phenomenon appears to be transient. The variability was found by ROSAT X-ray satellite. The intensity varied by a factor of 3 every 6,450 seconds (about 1.8 hours) based on observations by XMM-Newton in 2005, while in 2000 that period was estimated to be 4,200 seconds. It has been suggested that the source of the oscillation lies at the inner part of the accretion disk. The galaxy has been found to host a maser and is a compact source in radiowaves.

Nearby galaxies NGC 4253 belongs to a galaxy group known as LGG 276. Other members of this group includes the galaxies NGC 4131, NGC 4134, NGC 4169, NGC 4174, NGC 4175, NGC 4185, NGC 4196, NGC 4132, MCG 5-29-24, MCG 5-29-35, UGC 7221, and UGC 7294. NGC 4245 lies at a projected distance of 16.5 arcminuntes.

See also NGC 4593 – a similar barred galaxy which hosts an active nucleus NGC 5506 – another similar Seyfert galaxy

References

External links

NGC 4253 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images NGC 4253 on SIMBAD

Illustrations

Worked examples

Example 1 — a first encounter with NGC 4253

Start with the simplest possible case. Write down what NGC 4253 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 4253 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 4253 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 4253

In research: NGC 4253 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 4253 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 4253 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1788, Barred spiral galaxies, Coma Berenices, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 4253 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 4253 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 4253 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 4253 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 4253 in simple terms?

Why does NGC 4253 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 4253?

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 4253.