astronomy

NGC 1275

NGC 1275 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 1275 rather than just read about it. In short: NGC 1275 (also known as Perseus A or Caldwell 24) is a type 1.5 Seyfert galaxy located around 225 million light-years away from Earth in the direction of the constellation of Perseus. NGC 1275 is a member of the large Perseus Cluster of galaxies.

Key takeaways

NGC 1275 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 1275 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 1275 from memory before moving on to harder problems.

Reference excerpt

NGC 1275 (also known as Perseus A or Caldwell 24) is a type 1.5 Seyfert galaxy located around 225 million light-years away from Earth in the direction of the constellation of Perseus. NGC 1275 is a member of the large Perseus Cluster of galaxies. It was discovered by German-British astronomer William Herschel on 17 October 1786.

Properties

NGC 1275 consists of two galaxies, a central type-cD galaxy in the Perseus Cluster, and a so-called high velocity system (HVS) which lies in front of it. The HVS is moving at 3000 km/s towards the dominant system, and is believed to be merging with the Perseus Cluster. The HVS is not affecting the cD galaxy as it lies at least 200 thousand light years from it. However tidal interactions are disrupting it and the ram pressure produced by its interaction with the intracluster medium of Perseus is stripping its gas as well as producing large amounts of star formation within it.

The central cluster galaxy contains a massive network of spectral line emitting filaments, which apparently are being dragged out by rising bubbles of relativistic plasma generated by the central active galactic nucleus. Long gaseous filaments made up of threads of gas stretch out beyond the galaxy, into the multimillion-degree, X-ray–emitting gas that fills the cluster. The amount of gas contained in a typical thread is approximately one million times the mass of the Sun. They are only 200 light-years wide, are often very straight, and extend for up to 20,000 light-years. The existence of the filaments poses a problem. As they are much cooler than the surrounding intergalactic cloud, it is unclear how they have existed for such a long time, or why they have not warmed, dissipated or collapsed to form stars. One possibility is that weak magnetic fields (about one-ten-thousandth the strength of Earth's field) exert enough force on the ions within the threads to keep them together.

NGC 1275 contains 13 billion solar masses of molecular hydrogen that seems to be infalling from Perseus' intracluster medium in a cooling flow, both feeding its active nucleus and fueling significant amounts of star formation The presence of an active nucleus demonstrates that a supermassive black hole is present in NGC 1275's center. The black hole is surrounded by a rotating disk of molecular gas. High-resolution observations of the rotation of this disk obtained using adaptive optics at the Gemini North telescope indicate a central mass of approximately 800 million solar masses, including both the mass of the black hole and of the inner core of the gas disk.

Supernovae Three supernovae have so far been observed in NGC 1275:

SN 1968A (type unknown, mag. 15.5) was discovered by Miklós Lovas on 25 January 1968. SN 2005mz (Type Ia, mag. 18.2) was discovered by Jack Newton, Mike Peoples, and Tim Puckett on 31 December 2005. SN 2024xav (Type II-P, mag. 18.63) was discovered by GOTO on 2 October 2024.

See also List of NGC objects (1001–2000)

References

External links

NGC 1275 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images APOD (2003-05-05) – NASA image & description APOD (2005-07-25) – NASA image showing unusual gas filaments Fabian, A.C., et al. "A deep Chandra observation of the Perseus cluster: shocks and ripples". Monthly Notices of the Royal Astronomical Society. Vol. 344 (2003): L43 (arXiv:astro-ph/0306036v2). Fabian, A.C. Nature 454, 968–970. Gabany, R. Jay. cosmotography.com – An image made with a 20" telescope, which displays the unusual gas filaments

Illustrations

Worked examples

Example 1 — a first encounter with NGC 1275

Start with the simplest possible case. Write down what NGC 1275 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 1275 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 1275 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 1275

In research: NGC 1275 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 1275 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 1275 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 3C objects, Astronomical objects discovered in 1786, Caldwell objects, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 1275 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 1275 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 1275 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 1275 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 1275 in simple terms?

Why does NGC 1275 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 1275?

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 1275.