astronomy

NGC 7331 Group

NGC 7331 Group 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 7331 Group rather than just read about it. In short: The NGC 7331 Group is a visual grouping of galaxies located in the constellation Pegasus. The system is anchored by its largest member, NGC 7331, which lies approximately 40 million light-years (12.3 Mpc) from Earth.

Key takeaways

NGC 7331 Group 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 7331 Group to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 7331 Group from memory before moving on to harder problems.

Reference excerpt

The NGC 7331 Group is a visual grouping of galaxies located in the constellation Pegasus. The system is anchored by its largest member, NGC 7331, which lies approximately 40 million light-years (12.3 Mpc) from Earth. Apparent directly northeast of NGC 7331 are four smaller and much fainter galaxies, known as "the fleas":

NGC 7335: A lenticular galaxy located 290 million light-years (89 Mpc) away NGC 7336: A spiral galaxy located 370 million light-years (113 Mpc) away NGC 7337: A barred spiral galaxy located 300 million light-years (92 Mpc) away NGC 7340: An elliptical galaxy located 290 million light-years (89 Mpc) away

Physical vs. Visual Association Although historical catalogs grouped these objects together due to their visual close proximity , spectroscopic measurements from the NASA/IPAC Extragalactic Database (NED) confirm that the group is an optical grouping caused by line-of-sight alignment rather than a gravitationally bound cluster. While NGC 7331 sits in the foreground at a heliocentric radial velocity of 816 km/s (redshift 0.002722), the four background companion galaxies exhibit recessional velocities between 6,200 km/s and 8,800 km/s (redshift 0.021 to 0.029 Z). As a result, the four companion galaxies sit at distances ranging from 290 to 370 million light-years.

The true physical group bound to NGC 7331 consists of several satellite dwarf galaxies at matching distances, and NGC 7320 (which visually overlaps Stephan's Quintet), UGC 1206), and UGC 12160.

Nomenclature and History NGC 7331 was discovered by astronomer William Herschel on September 6, 1784. Swedish astronomer Erik Holmberg cataloged the visual system as Holm 795 in his 1937 study of multiple galaxies. The popular informal name "Deer Lick Group" was coined in the 1980s by American amateur astronomer Tom Lorenzin to commemorate an exceptional viewing session at the Deerlick Gap Overlook along the Blue Ridge Parkway in North Carolina, where he observed NGC 7331 along with its faint background companion galaxies.

See also Stephan's Quintet Wild's Triplet Zwicky's Triplet Robert's Quartet Seyfert's Sextet Copeland Septet NGC 7337 NGC 7320

External links "NAME NGC 7331 Group". SIMBAD. Centre de données astronomiques de Strasbourg. ADS: The NGC 7331 Group, a Stable Group of Galaxies Projected on Stephan's Quartet Nemiroff, R.; Bonnell, J., eds. (12 July 2008). "NGC 7331 and Beyond". Astronomy Picture of the Day. NASA.

NGC 7331 Group on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images 3–10 October 2008: Andromeda Galaxy (M31), Gamma Andromedae, and the NGC 7331 Group on Astronomy.com blog Archived 6 October 2008 at the Wayback Machine NGC 7331 Group at de-regt.com

References

Illustrations

Worked examples

Example 1 — a first encounter with NGC 7331 Group

Start with the simplest possible case. Write down what NGC 7331 Group 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 7331 Group 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 7331 Group 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 7331 Group

In research: NGC 7331 Group 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 7331 Group 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 7331 Group is common in secondary-school and first-year university syllabi. It links to neighbouring topics Galaxy clusters, NGC 7331 Group, Pegasus (constellation), so understanding it makes those chapters shorter.
In everyday life: Look for NGC 7331 Group 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 7331 Group in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 7331 Group 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 7331 Group out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 7331 Group in simple terms?

Why does NGC 7331 Group 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 7331 Group?

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 7331 Group.