astronomy

WISEA J120037.79−784508.3

WISEA J120037.79−784508.3 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 WISEA J120037.79−784508.3 rather than just read about it. In short: WISEA J120037.79−784508.3, also called W1200−7845 or 2MASS J12003792−7845082, is a brown dwarf with a primordial disk 333.73 ± 3.13 lightyears from Earth in the 3.7+4.6−1.4 Myr-old ε Chamaeleontis (ε Cha) association, currently making it the closest known brown dwarf with an associated circumstellar disk. It was discovered by citizen scientists in 2020 volunteering for the Disk Detective project.

Key takeaways

WISEA J120037.79−784508.3 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect WISEA J120037.79−784508.3 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of WISEA J120037.79−784508.3 from memory before moving on to harder problems.

Reference excerpt

WISEA J120037.79−784508.3, also called W1200−7845 or 2MASS J12003792−7845082, is a brown dwarf with a primordial disk 333.73 ± 3.13 lightyears from Earth in the 3.7+4.6−1.4 Myr-old ε Chamaeleontis (ε Cha) association, currently making it the closest known brown dwarf with an associated circumstellar disk. It was discovered by citizen scientists in 2020 volunteering for the Disk Detective project. Disk Detective's science team then cross-matched W1200−7845 with BANYAN Σ, a Bayesian analysis tool used to estimate the likelihood that an object is a member of a young moving group based on its position, proper motion, parallax (using Gaia DR2 data, if available) and radial velocity. The analysis revealed (with 99.8% probability) that the brown dwarf was a member of the ε Cha young moving group association.

Brown dwarf The brown dwarf has a mass of about 42–58 MJ and has a spectral type of about M6.0γ. The gamma (γ) signifies the low surface gravity of the object, which is typical for young brown dwarfs. No accretion was detected from paschen and brackett spectral lines. Later observations by Kubiak et al. 2021 found a strong H-alpha emission line, which indicates strong accretion of material. Named candidate #22 in their sample, it was the strongest accreting object in their entire sample.

Disk Three possible scenarios were considered for the disk: i) A blackbody disk (a disk with uniform temperature), ii) two blackbody disks (a disk with a gap) and iii) a power-law disk. The blackbody disk model has a temperature of 516 K (243°C; 469°F). The two-blackbodies model compromises of an inner disk with a temperature of 730 K (457°C; 854°F) and an outer disk with a temperature of 230 K (–43°C; –46°F). The best-fit model is a power-law disk with a power-law slope of α = –0.94, which is consistent with a class II disk. The close proximity of this system to the Solar System makes this disk a good candidate to image the disk with ALMA.

Illustrations

Worked examples

Example 1 — a first encounter with WISEA J120037.79−784508.3

Start with the simplest possible case. Write down what WISEA J120037.79−784508.3 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 WISEA J120037.79−784508.3 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 WISEA J120037.79−784508.3 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 WISEA J120037.79−784508.3

In research: WISEA J120037.79−784508.3 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 WISEA J120037.79−784508.3 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: WISEA J120037.79−784508.3 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 2020, Brown dwarfs, Chamaeleon, so understanding it makes those chapters shorter.
In everyday life: Look for WISEA J120037.79−784508.3 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 WISEA J120037.79−784508.3 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what WISEA J120037.79−784508.3 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 WISEA J120037.79−784508.3 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is WISEA J120037.79−784508.3 in simple terms?

Why does WISEA J120037.79−784508.3 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 WISEA J120037.79−784508.3?

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 WISEA J120037.79−784508.3.