astronomy

WISE J080822.18−644357.3

WISE J080822.18−644357.3 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 WISE J080822.18−644357.3 rather than just read about it. In short: WISE J080822.18-644357.3, also called J0808, is a 45+11−7 Myr old star system in the constellation Volans with a circumstellar debris disk orbiting an M-type red dwarf about 331 lightyears from Earth. On October 21, 2016, NASA's Goddard Space Flight Center announced that its citizen science project, Disk Detective, discovered a debris disk around J0808, using the WISE telescope, a M5.5V dwarf with significant infrar…

Key takeaways

WISE J080822.18−644357.3 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect WISE J080822.18−644357.3 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of WISE J080822.18−644357.3 from memory before moving on to harder problems.

Reference excerpt

WISE J080822.18-644357.3, also called J0808, is a 45+11−7 Myr old star system in the constellation Volans with a circumstellar debris disk orbiting an M-type red dwarf about 331 lightyears from Earth. On October 21, 2016, NASA's Goddard Space Flight Center announced that its citizen science project, Disk Detective, discovered a debris disk around J0808, using the WISE telescope, a M5.5V dwarf with significant infrared excess at both 12 and 22 μm. Classified as Peter Pan disk number AWI0005x3s in the project database—or 5x3s for short—a BANYAN II Bayesian analysis revealed (with 93.9% probability) the star's radial velocity as 20.6 ± 1.4 km/s, associating it with Carina's ~45 Myr old young moving group. Since most M-dwarf debris disks fade in less than 30 million years, this would be the oldest M dwarf debris disk detected in a moving group, implying a change in understanding of constraint in M-dwarf debris disk evolution. A follow-up study with an optical spectrum obtained with the ANU Siding Spring 2.3 meter telescope showed a Li-rich M5-star with strong Hα emission. The data is consistent with a low accretion of 10−10 M☉ yr −1. ALMA observations did not detect any carbon monoxide, but unresolved 1.3 mm dust emission was detected. Observations with CTIO showed a strong flare and variations in the Paschen-β and Brackett-γ lines, which is a clear sign of accretion.

Debris disk The fitting of a modeled disk with the Spectral Energy Distribution of J0808 indicates a disk temperature of about 263 K (-10 °C or 14 °F). The follow-up study found that a single disk had a poor match with the 22 μm data. The researchers found a better match with a "warm" outer disk with a temperature of about 240 K (-33 °C or -28 °F) and a "hot" inner disk with a temperature of about 1100 K (827 °C or 1520 °F). The warm outer disk is located around 0.115 au and the hot inner disk is located around 0.0056 au. The hot inner disk is likely the source of accreted material. The temperature of the inner disk is comparable to temperatures where amorphous silicates anneal into crystalline form. The inner disk also lies near the Roche limit of the red dwarf and therefore the inner disk could be the result of disrupted planetesimals. The warm outer disk could be similar to dust belts seen around B- to K-type stars, which have temperatures around 190 K and which likely represent small dust grains of sublimating ice from icy planetesimals. ALMA detected a third component with a temperature of 20 K (-253 °C or -424 °F). Using this temperature the researchers were able to estimate the dust mass to 0.057±0.006 M☉. This is higher than the disk mass around ~20 Myr old AU Microscopii and the ~50 Myr old GJ 182, but smaller than the ~10 Myr old TWA 7. The disk has a radius smaller than 16 au. The missing CO detection is explained with two possible scenarios: Either dust grains are released in a collisional cascade induced by the collisions of km-sized planetesimals or a recent collision of planetary bodies generated a large amount of small dust grains. A light curve from CTIO shows variations, which could be disk material blocking light from the star. The TESS light curve shows aperiodic dipping on timescales of 0.5–2 days.

Peter Pan disks Other stars and brown dwarfs were discovered to be similar to J0808, with signs of youth while being in an older moving group. Together with J0808, these older low-mass accretors in nearby moving groups are being called Peter Pan disks.

Gallery

Illustrations

Worked examples

Example 1 — a first encounter with WISE J080822.18−644357.3

Start with the simplest possible case. Write down what WISE J080822.18−644357.3 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 WISE J080822.18−644357.3 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 WISE J080822.18−644357.3 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 WISE J080822.18−644357.3

In research: WISE J080822.18−644357.3 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 WISE J080822.18−644357.3 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: WISE J080822.18−644357.3 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 2016, Circumstellar disks, M-type main-sequence stars, so understanding it makes those chapters shorter.
In everyday life: Look for WISE J080822.18−644357.3 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 WISE J080822.18−644357.3 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what WISE J080822.18−644357.3 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 WISE J080822.18−644357.3 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is WISE J080822.18−644357.3 in simple terms?

Why does WISE J080822.18−644357.3 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 WISE J080822.18−644357.3?

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 WISE J080822.18−644357.3.