astronomy

Sextans B

Sextans B 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 Sextans B rather than just read about it. In short: Sextans B (also known as UGC 5373 and DDO 70) is an irregular galaxy that may be part of the Local Group, or lie just beyond it. The earliest known reference to this galaxy is from a 1954 paper by Edison Pettit in The Astrophysical Journal, where it was listed as "Wilson Dwarf".

Key takeaways

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

Reference excerpt

Sextans B (also known as UGC 5373 and DDO 70) is an irregular galaxy that may be part of the Local Group, or lie just beyond it. The earliest known reference to this galaxy is from a 1954 paper by Edison Pettit in The Astrophysical Journal, where it was listed as "Wilson Dwarf". Sextans B is 4.44 million light-years away from Earth and thus is one of the most distant members of the Local Group, if it is indeed a member. It forms a pair with its neighbouring galaxy Sextans A. It is a type Ir IV–V galaxy according to the galaxy morphological classification scheme. Sextans B may also be gravitationally associated with the galaxies NGC 3109 and the Antlia Dwarf. Sextans B has a uniform stellar population, but the interstellar medium in it may be inhomogeneous. Its mass is estimated to be about 2×108 times the mass of the Sun, of which 5.5×107 is in the form of atomic hydrogen. Star formation in the galaxy seems to have proceeded in distinct periods of low intensity, separated by shorter periods of no activity. The existence of Cepheid variables in the galaxy implies that Sextans B contains at least some young stars. The metallicity of Sextans B is very low, with a value of approximately Z = 0.001. Sextans B is receding from the Milky Way with a speed of approximately 300 kilometres per second (190 mi/s), and probably lies just outside the edge of the Local Group, so as its neighbour Sextans A. Five planetary nebulae have been identified in Sextans B, which is one of the smallest galaxies where planetary nebulae have been observed. These appear point-like and can be identified by their spectral emission lines. It also contains a massive globular cluster. Although no supernovae have been observed in Sextans B, the galaxy is close enough for classical novae to be detected. The first confirmed nova in this galaxy was discovered by ATLAS at magnitude 18.553 on 10 November 2024, and designated AT 2024aawe.

References

External links

Sextans B on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images

Illustrations

Worked examples

Example 1 — a first encounter with Sextans B

Start with the simplest possible case. Write down what Sextans B 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 Sextans B 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 Sextans B 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 Sextans B

In research: Sextans B 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 Sextans B 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: Sextans B is common in secondary-school and first-year university syllabi. It links to neighbouring topics Dwarf galaxies, Irregular galaxies, MCG objects, so understanding it makes those chapters shorter.
In everyday life: Look for Sextans B 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 Sextans B in 20 minutes

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

Frequently asked questions

What is Sextans B in simple terms?

Why does Sextans B 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 Sextans B?

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 Sextans B.