astronomy

Black Widow pulsar

Black Widow pulsar 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 Black Widow pulsar rather than just read about it. In short: The Black Widow pulsar (PSR B1957+20) is an eclipsing binary millisecond pulsar in the Milky Way. Discovered in 1988, it is located roughly 6,500 light-years (2,000 parsecs) away from Earth.

Key takeaways

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

Reference excerpt

The Black Widow pulsar (PSR B1957+20) is an eclipsing binary millisecond pulsar in the Milky Way. Discovered in 1988, it is located roughly 6,500 light-years (2,000 parsecs) away from Earth. It completes a rotation period of 1.6074 milliseconds. It is orbited by a brown dwarf or super-Jupiter companion with a period of 9.2 hours with an eclipse duration of approximately 20 minutes. When it was discovered, it was the first such pulsar known.

Description The prevailing theoretical explanation for the system implied that the companion is being destroyed by the strong powerful outflows, or winds, of high-energy particles caused by the neutron star; thus, the sobriquet black widow pulsar was applied to the object. Subsequent to this, other objects with similar features have been discovered, and the name has been applied to the class of millisecond pulsars with an ablating companion, as of February 2023 around 41 black widows are known to exist.

Later observations of the object showed a bow shock in H-alpha and a smaller-in-extent shock seen in X-rays (as observed by the Chandra X-ray Observatory), indicating a forward velocity of approximately a million kilometers per hour. In 2010, it was estimated that the neutron star's mass was at least 1.66 M ⊙ {\displaystyle 1.66M_{\odot }} and possibly as high as 2.4 M ⊙ {\displaystyle 2.4M_{\odot }} (the latter of which, if true, would surpass PSR J0740+6620 for the title of most massive neutron star yet detected and place it within range of the Tolman–Oppenheimer–Volkoff limit). In January 2023 the upper limit was revised down to 1.8 M ⊙ {\displaystyle 1.8M_{\odot }}

Planets The pulsar has a substellar companion, possibly a brown dwarf.

Gallery Artist impressions of the Black Widow pulsar and an optical image of the bow shock.

Illustrations

Worked examples

Example 1 — a first encounter with Black Widow pulsar

Start with the simplest possible case. Write down what Black Widow pulsar 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 Black Widow pulsar 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 Black Widow pulsar 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 Black Widow pulsar

In research: Black Widow pulsar 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 Black Widow pulsar 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: Black Widow pulsar is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1988, Eclipsing binaries, Low-mass X-ray binaries, so understanding it makes those chapters shorter.
In everyday life: Look for Black Widow pulsar 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 Black Widow pulsar in 20 minutes

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

Frequently asked questions

What is Black Widow pulsar in simple terms?

The Black Widow pulsar (PSR B1957+20) is an eclipsing binary millisecond pulsar in the Milky Way. Discovered in 1988, it is located roughly 6,500 light-years (2,000 parsecs) away from Earth.

Why does Black Widow pulsar 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 Black Widow pulsar?

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 Black Widow pulsar.