astronomy

NGC 5701

NGC 5701 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 5701 rather than just read about it. In short: NGC 5701 is a barred lenticular galaxy with a ring located in the constellation Virgo. It lies at a distance of about 50 million light years from Earth based on redshift-independent methods, which, given its apparent dimensions, means that NGC 5701 is about 65,000 light years across.

Key takeaways

NGC 5701 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 5701 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 5701 from memory before moving on to harder problems.

Reference excerpt

NGC 5701 is a barred lenticular galaxy with a ring located in the constellation Virgo. It lies at a distance of about 50 million light years from Earth based on redshift-independent methods, which, given its apparent dimensions, means that NGC 5701 is about 65,000 light years across. Based on redshift the galaxy lies at a distance of 85 million light years. It was discovered by William Herschel on April 29, 1786.

Characteristics

Central region The galaxy is categorised as a barred lenticular galaxy. The bar is faint and diffuse, and almost completely dust-free. At its ends it has elevated brightness, forming ansae. It surrounds a large, bright and slightly elliptical bulge with a bright nucleus. The bar lies inside a disk which mostly lacks features, with the exception of some knots or possible companion galaxies. The bar is strong and dominates the disk, while the bulge component could overlap with the disk, making the galaxy appear to lack a disk. The lack of disk however could be the result of a model that lacks the bar as different models indicate the presence of the disk. An inner ring is detectable at the end of the bar. The stellar population in the barlens is mostly old, as 70–85% of the stellar mass is older than 10 billion years. The intermediate age stars are more common at the outer edges of the barlens. The bar doesn't show to induse star formation. At the centre the metallicity is solar and becomes subsolar towards the edges, and is higher than that of the bulge of the Milky Way. Gas and stellar velocity fields are slightly offset with each other as indicated by the position angles of their major axes. The isophotes indicate that the bar is also misaligned with the stellar velocity field. The nucleus of the galaxy has been found to be active and based on its emission lines has been identified as a transitional object between an HII region and a LINER. The most accepted theory for the energy source of active galactic nuclei is the presence of an accretion disk around a supermassive black hole. The mass of the black hole in the centre of NGC 5701 is estimated to be 107.9 (80 million) M☉ based on the absolute bulge magnitude. A faint nuclear spiral is visible in images by the Hubble Space Telescope extending to about 10 arcseconds. As the galaxy is seen nearly face-on it is difficult to detect if an inner disk is present. The nuclear spiral is associated with young stars, whose presence however is negligible as far as the total stellar mass of the bulge is concerned.

Outer ring

The galaxy has an outer pseudo-ring which is more visible in blue light. The ring is created by two arms which emerge from the end of the disk, but they start to branch into smaller arms, creating a ring of multiple fragmented arms. Many HII regions emitting H-alpha are visible in it, indicating it is a location of active star formation. The ring is detached from the disk and gives the galaxy an appearance similar to Hoag's Object. It is possible that the bar prevents the gas infalling to the central region of the galaxy. The ring is elongated perpendicularly to the bar.

Hydrogen disk The optical disk is surrounded by a hydrogen envelope which extends to over 10 arcminutes from the nucleus, about two and half times more than the optical edge of the galaxy. The HI emission is about twice as strong at the west of the galaxy than the east but its western edge is sharper. The asymmetry could be the result of a past interaction with another galaxy. Observations by the Arecibo Observatory revealed an HI cloud about 15 arcminutes northwest of the centre but it wasn't detected in observations by the Very Large Array.

Nearby galaxies NGC 5701 is according to A. M. Garcia a member of the NGC 5746 Group, also known as LGG 386. No companion galaxies are visible in hydrogen line or optical observations. UGC 9385, another member of the group, lies about 56 arcminutes to the west. The group is a member of the Virgo III Groups, a long chain of galaxies extending for about 40 million light years from the Virgo Cluster.

References

External links

NGC 5701 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images NGC 5701 on SIMBAD

Illustrations

Worked examples

Example 1 — a first encounter with NGC 5701

Start with the simplest possible case. Write down what NGC 5701 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 5701 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 5701 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 5701

In research: NGC 5701 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 5701 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 5701 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1786, Barred lenticular galaxies, Discoveries by William Herschel, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 5701 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 5701 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 5701 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 5701 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 5701 in simple terms?

Why does NGC 5701 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 5701?

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 5701.