astronomy

NGC 3115

NGC 3115 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 3115 rather than just read about it. In short: NGC 3115 (also called the Spindle Galaxy or Caldwell 53) is a field lenticular (S0) galaxy in the constellation Sextans. The galaxy was discovered by William Herschel on February 22, 1787.

Key takeaways

NGC 3115 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 3115 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 3115 from memory before moving on to harder problems.

Reference excerpt

NGC 3115 (also called the Spindle Galaxy or Caldwell 53) is a field lenticular (S0) galaxy in the constellation Sextans. The galaxy was discovered by William Herschel on February 22, 1787. At about 32 million light-years away from Earth, it is several times bigger than the Milky Way. It is a lenticular (S0) galaxy because it contains a disk and a central bulge of stars, but without a detectable spiral pattern. NGC 3115 is seen almost exactly edge-on, but was nevertheless mis-classified as elliptical. There is some speculation that NGC 3115, in its youth, was a quasar. One supernova has been observed in NGC 3115: SN 1935B (type and mag. unknown).

Star formation NGC 3115 has consumed most of the gas of its youthful accretion disk. It has very little gas and dust left that would trigger new star formation. The vast majority of its component stars are very old.

Black hole In 1992 John Kormendy of the University of Hawaii and Douglas Richstone of the University of Michigan announced what was observed to be a supermassive black hole in the galaxy. Based on orbital velocities of the stars in its core, the central black hole has mass measured to be approximately one billion solar masses (M☉). The galaxy appears to have mostly old stars and little or no activity. The growth of its black hole has also stopped. In 2011, NASA's Chandra X-ray Observatory examined the black hole at the center of the large galaxy. A flow of hot gas toward the supermassive black hole has been imaged, making this the first time clear evidence for such a flow has been observed in any black hole. As gas flows toward the black hole, it becomes hotter and brighter. The researchers found the rise in gas temperature begins at about 700 light years from the black hole, giving the location of the Bondi radius. This suggests that the black hole in the center of NGC 3115 has a mass of about two billion M☉, supporting previous results from optical observations. This would make NGC 3115 the nearest billion-solar-mass black hole to Earth.

See also NGC 5866 – another lenticular galaxy sometimes referred to as the Spindle Galaxy

References

External links

Chandra Press Release SEDS: NGC 3115 NGC 3115 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images

Illustrations

Worked examples

Example 1 — a first encounter with NGC 3115

Start with the simplest possible case. Write down what NGC 3115 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 3115 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 3115 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 3115

In research: NGC 3115 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 3115 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 3115 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Caldwell objects, Field galaxies, Galaxies discovered in 1787, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 3115 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.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study NGC 3115 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 3115 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 3115 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 3115 in simple terms?

NGC 3115 (also called the Spindle Galaxy or Caldwell 53) is a field lenticular (S0) galaxy in the constellation Sextans. The galaxy was discovered by William Herschel on February 22, 1787.

Why does NGC 3115 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 3115?

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 3115.