astronomy

NGC 6751

NGC 6751 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 6751 rather than just read about it. In short: NGC 6751, also known as the Glowing Eye Nebula, is a planetary nebula in the constellation Aquila. It is estimated to be about 6,500 light-years (2.0 kiloparsecs) away.

Key takeaways

NGC 6751 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 6751 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 6751 from memory before moving on to harder problems.

Reference excerpt

NGC 6751, also known as the Glowing Eye Nebula, is a planetary nebula in the constellation Aquila. It is estimated to be about 6,500 light-years (2.0 kiloparsecs) away. NGC 6751 was discovered by the astronomer Albert Marth on 20 July 1863. John Louis Emil Dreyer, the compiler of the New General Catalogue, described the object as "pretty bright, small". The object was assigned a duplicate designation, NGC 6748. The nebula was the subject of the winning picture in the 2009 Gemini School Astronomy Contest, in which Australian high school students competed to select an astronomical target to be imaged by Gemini. NGC 6751 is an easy telescopic target for deep-sky observers because its location is immediately southeast of the extremely red-colored cool carbon star V Aquilae.

Properties NGC 6751, like all planetary nebulae was formed when a dying star threw off its outer layers of gas several thousand years ago. It is estimated to be around 0.8 light-years in diameter. NGC 6751 has a complex bipolar structure. There is a bright, inner bubble (shown in the photo), as well as two fainter halos. (The outer halo, with a radius of 50″ is extremely faint and is broken, while the inner halo with a radius of 27″ is roughly spherical). On both the west and east sides of the inner shell, knots can be seen that are surrounded by faint "lobes". These lobes are actually a ring, and the eastern side is nearer than the western side. As a whole, the system is approaching the Solar System with a heliocentric radial velocity of −31.7 km/s. The central star of the nebula has a similar spectrum to a Wolf–Rayet star (spectral type [WC4]), and has an effective temperature of about 140,000 K and a radius of about 0.13 R☉. It is losing mass at a rate of 1×10−6 M☉ per year, and its surface composition is mostly helium and carbon. The winning image of the 2009 Gemini Astronomy Contest shows a nebula at the top left of NGC 6751. This 80 x 40 arcsec nebula was discovered in 1990 by Hua & Louise at the Newton focus of the Foucault telescope, 120cm in diameter at Observatoire de Haute Provence (O.H.P.) Saint Michel l'Observatoire.

Illustrations

Worked examples

Example 1 — a first encounter with NGC 6751

Start with the simplest possible case. Write down what NGC 6751 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 6751 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 6751 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 6751

In research: NGC 6751 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 6751 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 6751 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aquila (constellation), Henry Draper Catalogue objects, NGC objects, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 6751 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 6751 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 6751 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 6751 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 6751 in simple terms?

NGC 6751, also known as the Glowing Eye Nebula, is a planetary nebula in the constellation Aquila. It is estimated to be about 6,500 light-years (2.0 kiloparsecs) away.

Why does NGC 6751 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 6751?

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 6751.