astronomy

J1407b

J1407b 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 J1407b rather than just read about it. In short: J1407b is an astronomical object proposed to explain a series of eclipse-like dimming events observed in the star V1400 Centauri during 2007. These dimming events were recorded by automated telescopes that year but were not identified until 2010, when Mark Pecaut and Eric Mamajek analyzed the data.

Key takeaways

J1407b belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect J1407b to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of J1407b from memory before moving on to harder problems.

Reference excerpt

J1407b is an astronomical object proposed to explain a series of eclipse-like dimming events observed in the star V1400 Centauri during 2007. These dimming events were recorded by automated telescopes that year but were not identified until 2010, when Mark Pecaut and Eric Mamajek analyzed the data. J1407b was initially thought to be a planet with a massive ring system orbiting V1400 Centauri, but no new eclipses have ever been observed, nor do historical photographic plates show evidence for eclipses in the last century, so this explanation is unlikely. Astronomers have alternatively proposed that J1407b might have been a free-floating substellar object with a protoplanetary disk that coincidentally eclipsed V1400 Centauri, a hypothesis that is still the most likely to date. J1407b's hypothetical disk spans a radius of about 90 million km (0.60 AU; 56 million mi) and consists of many rings and gaps which may indicate the formation of moons in orbit around the object. Follow-up observations have attempted to detect J1407b via high-resolution imaging, but found no object. The non-detection of J1407b places constraints on the nature of its disk, ruling out one dominated by grains with sizes over one millimeter.

2007 dimming and discovery During 7 April to 4 June 2007, telescopes of the Super Wide Angle Search for Planets (SuperWASP) and All Sky Automated Survey (ASAS) projects automatically recorded V1400 Centauri undergoing a series of significant dimming events for 56 days. The pattern of these dimming events was complex yet nearly symmetrical, suggesting they were caused by an opaque, disk-like structure eclipsing the star. The light curve of V1400 Centauri during 2007 showed at least five major dimming events, including one long and very deep central eclipse bracketed by two pairs of shorter eclipses symmetrically occurring 12 days and 26 days before and after the middle of the deep eclipse. The deep eclipse lasted about 14 days and blocked out at least 95% of V1400 Centauri's light, causing it to dim by at least 3.3 magnitudes. The short eclipses before and after the deep eclipse blocked out at least 60% of the star's light, causing it to dim by at least 1 magnitude. The event was not noticed until 3 December 2010, when Mark J. Pecaut, a graduate student of Eric E. Mamajek at the University of Rochester, discovered V1400 Centauri's 2007 dimming while investigating SuperWASP's public light curve database. Pecaut and Mamajek were originally intending to use the SuperWASP data to check for brightness variability in candidate low-mass stars of the Scorpius–Centaurus association, which they had been studying since 2009. Mamajek, Pecaut, and collaborators presented their discovery of V1400 Centauri's dimming in January 2012 at the 219th American Astronomical Society conference in Austin, Texas, and then formally published their results in The Astronomical Journal in March 2012.

Name The object was first dubbed "J1407b" in a paper published by Tim van Werkhoven, Matthew Kenworthy, and Eric Mamajek in 2014, which assumed the object was orbiting V1400 Centauri as an exoplanet. The name J1407b follows the exoplanet naming convention by adding the letter "b" after the host star's name. At the time of J1407b's discovery, V1400 Centauri was known as "J1407", which is the shortened form of the star's full SuperWASP catalogue designation 1SWASP J140747.93–394542.6. This designation shows the star's location in the sky in equatorial coordinates.

Disk and potential exomoons

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with J1407b

Start with the simplest possible case. Write down what J1407b 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 J1407b 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 J1407b 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 J1407b

In research: J1407b 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 J1407b 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: J1407b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 2012, Centaurus, Circumstellar disks, so understanding it makes those chapters shorter.
In everyday life: Look for J1407b 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 J1407b in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what J1407b 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 J1407b out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is J1407b in simple terms?

Why does J1407b 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 J1407b?

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 J1407b.