astronomy

WR 42e

WR 42e 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 WR 42e rather than just read about it. In short: WR 42e (2MASS J11144550-115001) is a Wolf–Rayet star in the massive H II region NGC 3603 in the constellation of the Carina. It is around 25,000 light-years or 7,600 parsec from the Sun.

Key takeaways

WR 42e belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect WR 42e to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of WR 42e from memory before moving on to harder problems.

Reference excerpt

WR 42e (2MASS J11144550-115001) is a Wolf–Rayet star in the massive H II region NGC 3603 in the constellation of the Carina. It is around 25,000 light-years or 7,600 parsec from the Sun. WR 42e is one of the most massive and most luminous stars known. WR 42e was first catalogued in 2004 as a member of NGC 3603, numbered 954. It was noted as having x-ray and Hα emission. A detailed study published in 2012 showed that the faint red star was actually a highly obscured (6.4 magnitudes in the visual) hot blue Wolf Rayet star and gave it the name WR 42e. Subsequent changes to the naming conventions for new galactic Wolf–Rayet stars mean it is also called WR 42-1. WR 42e is located 2.7 arcmin west-northwest of the massive open cluster HD 97950 at the heart of NGC 3603, corresponding to 6 parsecs at the distance of NGC 3603. This is outside the compact core of the cluster where similar massive luminous stars are found. It is speculated that WR 42e was ejected in an unusual three-body encounter possibly involving the merger of two of the stars (which formed WR 42e) and the ejection of both the resulting objects. The spectrum of WR 42e shows many characteristics of an OIf* star, such as hydrogen Balmer series absorption lines and emission lines of ionised nitrogen and helium. The relative strengths of the nitrogen emission lines and the lack of absorption in the 468.4 nm helium line indicate a spectral class of O3 If*. However, the Hβ line shows a distinct emission wing. A P Cygni profile for this line is a defining character of the OIf*/WN class and so WR 42e is assigned the type O3If*/WN6.

Illustrations

Worked examples

Example 1 — a first encounter with WR 42e

Start with the simplest possible case. Write down what WR 42e 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 WR 42e 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 WR 42e 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 WR 42e

In research: WR 42e 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 WR 42e 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: WR 42e is common in secondary-school and first-year university syllabi. It links to neighbouring topics Carina (constellation), NGC 3603, O-type supergiants, so understanding it makes those chapters shorter.
In everyday life: Look for WR 42e 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 WR 42e in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what WR 42e 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 WR 42e out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is WR 42e in simple terms?

WR 42e (2MASS J11144550-115001) is a Wolf–Rayet star in the massive H II region NGC 3603 in the constellation of the Carina. It is around 25,000 light-years or 7,600 parsec from the Sun.

Why does WR 42e 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 WR 42e?

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 WR 42e.