astronomy

V391 Pegasi b

V391 Pegasi 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 V391 Pegasi b rather than just read about it. In short: V391 Pegasi b, also known as HS 2201+2610 b, is an extrasolar planet candidate orbiting the star V391 Pegasi approximately 4,570 light-years away in the constellation of Pegasus. The candidate planet was discovered by means of variable star timing, which measured anomalies in variability of the star caused by a planet.

Key takeaways

V391 Pegasi 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 V391 Pegasi b to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of V391 Pegasi b from memory before moving on to harder problems.

Reference excerpt

V391 Pegasi b, also known as HS 2201+2610 b, is an extrasolar planet candidate orbiting the star V391 Pegasi approximately 4,570 light-years away in the constellation of Pegasus. The candidate planet was discovered by means of variable star timing, which measured anomalies in variability of the star caused by a planet. It is the first planet candidate to claim to be detected with this method. The discovery reported the planet candidate to have mass of 3.2 times Jupiter's (assuming an edge-on orbit), semi-major axis of 1.7 AU, and orbital period of 1,170 days. The planet candidate was discovered in March 2007 and published in September 2007. If it is confirmed, its survival would indicate that planets at Earth-like distances can survive their star's red-giant phase, though this is a much larger planet than Earth (about the same size as Jupiter and Saturn). Its existence has been called into question with further monitoring of the pulsations of the star which show deviations from the predicted behavior if this were in fact a planet. The variations in the pulsations may be due to unknown stellar variability.

References R. Silvotti; S. Schuh; R. Janulis; S. Bernabei; R. Ostensen; J.-E. Solheim; I. Bruni; R. Gualandi; T. Oswalt; A. Bonanno; B. Mignemi; the Whole Earth Telescope Xcov23 collaboration (2007). "The O-C diagram of the subdwarf B pulsating star HS2201+2610: detection of a giant planet?". ASP Conference Series. 372: 369. arXiv:astro-ph/0703753. Bibcode:2007ASPC..372..369S.{{cite journal}}: CS1 maint: numeric names: authors list (link) R. Silvotti; S. Schuh; R. Janulis; J.-E. Solheim; S. Bernabei; R. Østensen; T. D. Oswalt; I. Bruni; R. Gualandi; A. Bonanno; G. Vauclair; M. Reed; C.-W. Chen; E. Leibowitz; M. Paparo; A. Baran; S. Charpinet; N. Dolez; S. Kawaler; D. Kurtz; P. Moskalik; R. Riddle & S. Zola (2007). "A giant planet orbiting the 'extreme horizontal branch' star V 391 Pegasi" (PDF). Nature. 449 (7159): 189–191. Bibcode:2007Natur.449..189S. doi:10.1038/nature06143. PMID 17851517. S2CID 4342338.

External links The Extrasolar Planets Encyclopaedia: Notes for planet V391 Pegasi b

Illustrations

Worked examples

Example 1 — a first encounter with V391 Pegasi b

Start with the simplest possible case. Write down what V391 Pegasi 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 V391 Pegasi 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 V391 Pegasi 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 V391 Pegasi b

In research: V391 Pegasi 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 V391 Pegasi 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: V391 Pegasi b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exoplanet stubs, Exoplanets detected by timing, Exoplanets discovered in 2007, so understanding it makes those chapters shorter.
In everyday life: Look for V391 Pegasi 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 V391 Pegasi b in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what V391 Pegasi 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 V391 Pegasi b out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is V391 Pegasi b in simple terms?

Why does V391 Pegasi 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 V391 Pegasi 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 V391 Pegasi b.