astronomy

PGC 29820

PGC 29820 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 PGC 29820 rather than just read about it. In short: PGC 29820 (known as JO204) is a spiral galaxy 600 million light-years from the Solar System, in the Sextans constellation. The galaxy is about 120,000 light-years in diameter and is a member of Abell 957, a low-mass galaxy cluster.

Key takeaways

PGC 29820 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect PGC 29820 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of PGC 29820 from memory before moving on to harder problems.

Reference excerpt

PGC 29820 (known as JO204) is a spiral galaxy 600 million light-years from the Solar System, in the Sextans constellation. The galaxy is about 120,000 light-years in diameter and is a member of Abell 957, a low-mass galaxy cluster. The first known reference to this galaxy is from volume I of the Catalogue of Galaxies and of Clusters of Galaxies compiled by Fritz Zwicky in 1961, where it was listed as CGCG 008-077.

Characteristics PGC 29820 is classified a massive galaxy with a stellar mass of M* =4 × 1010 M. It contains an active galactic nucleus with double-peaked narrow lines. Moreover, it is also a Seyfert 2 galaxy. PGC 29820 is classified a jellyfish galaxy. According to Gullieuszik, the galaxy is currently in a first phrase of infalling into the cluster where it is subjected to ram pressure by the intracluster medium. Because dense gas is compressed, it eventually collapses to form new stars in both the galaxy's tail and its disk. According to researchers, the stars inside the tail, has a star formation rate of 0.22 M○ yr1 which began during the last 500 million years. In additional, PGC 29820 shows a large presence of molecular gas making up H2 mass of 8.3 billion M○. Looking at ratio of total molecular hydrogen mass and stellar mass, it is estimated as 0.42.

See also IC 4141 PGC 65543 PGC 1228197 ESO 137-001

References

Illustrations

Worked examples

Example 1 — a first encounter with PGC 29820

Start with the simplest possible case. Write down what PGC 29820 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 PGC 29820 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 PGC 29820 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 PGC 29820

In research: PGC 29820 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 PGC 29820 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: PGC 29820 is common in secondary-school and first-year university syllabi. It links to neighbouring topics LEDA objects, Principal Galaxies Catalogue objects, Sextans, so understanding it makes those chapters shorter.
In everyday life: Look for PGC 29820 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 PGC 29820 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what PGC 29820 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 PGC 29820 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is PGC 29820 in simple terms?

Why does PGC 29820 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 PGC 29820?

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 PGC 29820.