astronomy

NGC 4424

NGC 4424 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 4424 rather than just read about it. In short: NGC 4424 is a spiral galaxy located in the equatorial constellation of Virgo. It was discovered February 27, 1865 by German astronomer Heinrich Louis d'Arrest.

Key takeaways

NGC 4424 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 4424 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 4424 from memory before moving on to harder problems.

Reference excerpt

NGC 4424 is a spiral galaxy located in the equatorial constellation of Virgo. It was discovered February 27, 1865 by German astronomer Heinrich Louis d'Arrest. This galaxy is located at a distance of 13.5 million light years and is receding with a heliocentric radial velocity of 442 km/s. It has a morphological class of SB(s)a, which normally indicates a spiral galaxy with a barred structure (SB), no inner ring feature (s), and tightly-wound spiral arms (a). The galactic plane is inclined at an angle of 62° to the line of sight from the Earth. It is a likely member of the Virgo Cluster of galaxies.

The galaxy NGC 4424 has a peculiar morphology with shells that give the appearance of a galaxy merger within the last half billion years. It has a long tail of hydrogen stretching 110 kpc to the south that is likely due to stripping from ram pressure. Because of the lack of gas, star formation has completely ceased in the outer parts of the galaxy, while there is still a mild amount occurring in the inner region. NGC 4424 will most likely end up as a lenticular galaxy by three billion years from now. There is no indication of an active, compact source of X-ray emission at the very center of NGC 4424, but there is an ionized tail stretching ~10 kpc from the core. Based on its stellar mass and velocity dispersion, the galaxy's center is predicted to host an intermediate-mass black hole (IMBH) of approximately (0.8±0.2)×105 M☉. Hubble images show a red, tidally stretched star cluster—named "Nikhuli"—located at a projected distance of about 5″ (~400 pc) from the nucleus. Nikhuli has a stellar mass of (3.44±0.93)×106 M☉ and is elongated toward the galaxy's center, suggesting it may be the captured nuclear star cluster of a stripped galaxy undergoing tidal shredding during a minor merger. Coincident with Nikhuli is an X-ray point source, NGC 4424 X-3, which exhibits a luminosity of L0.5–8 keV ≈ 6×1038 erg s−1 and is interpreted as an active massive black hole (with an estimated mass of ∼0.7×105 M☉). This cluster is expected to sink to the center of NGC 4424 due to dynamical friction on a timescale of roughly 100 to 220 million years, potentially seeding the bulgeless host with its central black hole. The discovery of Nikhuli and its potential role in black hole seeding attracted widespread coverage in popular science and mainstream media.

Supernovae Two supernovae have been observed in NGC 4424:

SN 1895A (type unknown, mag. 12.5) was discovered by Max Wolf on March 16, 1895. SN 2012cg (Type Ia, mag. 16.9) was discovered by the LOSS program from images taken on May 17, 2012. It reached maximum light (mag. 11.9) nine days later and became the brightest supernova of the year 2012. The supernova reached a peak absolute magnitude of −19.50±0.31 in the B (blue) band and synthesized 0.72±0.31 M☉ of the radioactive isotope nickel-56. The available observations favor a merger of double degenerate progenitors as the source for the event. The proximity of the galaxy made this one of the best studied supernova explosions to date.

References

External links Media related to NGC 4424 at Wikimedia Commons

Illustrations

Worked examples

Example 1 — a first encounter with NGC 4424

Start with the simplest possible case. Write down what NGC 4424 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 4424 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 4424 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 4424

In research: NGC 4424 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 4424 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 4424 is common in secondary-school and first-year university syllabi. It links to neighbouring topics NGC objects, Peculiar galaxies, Principal Galaxies Catalogue objects, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 4424 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 4424 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 4424 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 4424 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 4424 in simple terms?

NGC 4424 is a spiral galaxy located in the equatorial constellation of Virgo. It was discovered February 27, 1865 by German astronomer Heinrich Louis d'Arrest.

Why does NGC 4424 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 4424?

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 4424.