astronomy

NGC 1700

NGC 1700 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 1700 rather than just read about it. In short: NGC 1700 is an elliptical galaxy located in the constellation Eridanus. It is located at a distance of about 120 million light years from Earth based on redshift-independent methods, which, given its apparent dimensions, means that NGC 1700 is about 110,000 light years across.

Key takeaways

NGC 1700 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 1700 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 1700 from memory before moving on to harder problems.

Reference excerpt

NGC 1700 is an elliptical galaxy located in the constellation Eridanus. It is located at a distance of about 120 million light years from Earth based on redshift-independent methods, which, given its apparent dimensions, means that NGC 1700 is about 110,000 light years across. Based on its redshift, the galaxy sits roughly 170 million light years away from the Sun. It was discovered by William Herschel on October 5, 1785.

Characteristics NGC 1700 is an elliptical galaxy that formed after the merger of at least two galaxies. The galaxy has boxy isophotes and has two broad tidal tails or plumes extending towards the north-west and south-east of the galaxy for about 165 arcseconds, which corresponds to 41,000 parsecs (130,000 ly) at the distance of the galaxy. A faint shell system is visible in the central 25 arcseconds of the galaxy. Chaotic dust clouds have been observed within two arcseconds from the centre of the galaxy. They lie at an angle of 45 degrees with respect to the major axis of the galaxy. The presence of two symmetrical tails indicates that the galaxy was formed from two spiral galaxies, or possibly a spiral galaxy and an elliptical galaxy. Based on the morphology of the tails, Brown estimated in 2000 the merger took place 3.2 ± 1.5 billion years ago, while Schweizer and Seitzer estimated in 1992 it took place 6 billion years ago.

Observations of the galaxy by the Chandra X-ray Observatory revealed the presence of an extended disk of hot gas with a diameter of 90,000 light years glowing in X-rays. Upon discovery, it was the largest disk of hot gas known. The disk appears flattened at the outer parts of the galaxy, indicating it is rotating. The temperature of the gas is estimated to be 0.47 ± 0.03 keV. The hot gas disk was accreted during the merger and given the gas cooling rate, the merger took place 3 billion years ago. The rotation implies it continues to carry its initial momentum. The Hubble Space Telescope found 146 globular clusters in NGC 1700. The globular clusters with an apparent magnitude brighter than 24.5 show a twin peak distribution in color, at V−I=0.85 ± 0.05 and V−I=1.15 ± 0.05, which were also present in images taken by the Keck Observatory, where 312 globular clusters were detected. The blue population has similar color to the globular clusters in Milky Way and is representative of old metal-poor clusters, while the red population has higher metallicity, higher than the solar one, and is younger, with an estimated age of 2.5 to 5 billion years by Brown et al, while Trancho et al estimated an age of 1.7 ± 0.8 billion years for the younger clusters. The stellar population in the core of the galaxy is younger than the rest of the galaxy, having an estimated age of about 6 billion years. The stars in the core are rotating at the opposite direction as the rest of the galaxy, and the core is characterised as kinematically decoupled. It is possible this characteristic is the result of the accretion of a smaller counter-rotating companion galaxy in an event separate from that which created the tidal tails. Statler et al estimated that the merger which resulted in the kinematically decoupled core took place 2 to 4 billion years ago. In the centre of the galaxy lies a supermassive black hole whose mass is estimated to be about 425 million M☉ based on the bulge mass-black hole mass relation.

Nearby galaxies NGC 1700 belongs to a galaxy group known as LGG 123. Other members of the group include the galaxies NGC 1729, NGC 1741, IC 2102, and IC 399. NGC 1699 lies at a projected distance of 6.5 arcminutes.

References

External links

NGC 1700 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images NGC 1700 on SIMBAD

Illustrations

Worked examples

Example 1 — a first encounter with NGC 1700

Start with the simplest possible case. Write down what NGC 1700 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 1700 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 1700 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 1700

In research: NGC 1700 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 1700 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 1700 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1785, Discoveries by William Herschel, Elliptical galaxies, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 1700 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 1700 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 1700 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 1700 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 1700 in simple terms?

Why does NGC 1700 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 1700?

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 1700.