science

MAXI J1820+070

MAXI J1820+070 is a science 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 MAXI J1820+070 rather than just read about it. In short: MAXI J1820+070 is an X-ray binary system in the equatorial constellation of Ophiuchus. It was discovered in 2018, when it underwent a flare event, becoming one of the brightest such objects ever observed (in both the visual and X-ray bands).

Key takeaways

MAXI J1820+070 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect MAXI J1820+070 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of MAXI J1820+070 from memory before moving on to harder problems.

Reference excerpt

MAXI J1820+070 is an X-ray binary system in the equatorial constellation of Ophiuchus. It was discovered in 2018, when it underwent a flare event, becoming one of the brightest such objects ever observed (in both the visual and X-ray bands). Based on parallax measurements, it is located at a distance of approximately 9.7 ± 1.1 kly (2.96 ± 0.33 kpc) from the Sun.

Discovery This target was discovered March 6, 2018 by the All Sky Automated Survey for SuperNovae at an apparent visual magnitude of 14.88. Previously it had been at magnitudes below 16.7. On March 11, X-ray emission from this source was detected by the MAXI telescope, mounted on the International Space Station. On March 13, the Swift Burst Alert Telescope was triggered by MAXI J1820+070. Subsequently, the source underwent three re-brightenings that were extensively monitored, before its final optical activity was observed in April 2021. It began fading rapidly in June 2023 and returned to quiescence at its pre-brightening level after five years.

Observations Optical observations of this transient source, combined with distance estimates, indicated it is consistent with a low-mass X-ray binary system containing a candidate black hole. The spectra displayed hydrogen absorption lines with emission cores, suggesting an accretion disk undergoing outburst. By April 4, 2018, quasi-periodic oscillations had been observed in both the X-ray and visual bands with variability on time scales of less than a second. Optical variation of 0.03–0.10 in magnitude showed a periodicity of 3.4 hours, suggesting this may be the orbital period. In 2019, the presence of a black hole in the system was confirmed through measurements of the system dynamics. The cool, evolved, low mass companion is transferring matter via its Roche lobe to an accretion disk orbiting the black hole. This disk is truncated at around 51 times the gravitational radii, and has a high density of around 1020 cm−3. Observations suggest the disk may be warped and is precessing. The black hole has an estimated spin parameter of a ~ 0.77 ± 0.21. An accurate radio parallax measurement was made in 2020, providing a distance estimate of 9,700 ± 1,100 ly. The detection of knots in the ejecta allowed the angle of the jet to be measured as 64°±5° to the plane of the sky relative to Earth. The ejecta is moving at ~0.97 c, where c is the speed of light.

References

Illustrations

Worked examples

Example 1 — a first encounter with MAXI J1820+070

Start with the simplest possible case. Write down what MAXI J1820+070 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 MAXI J1820+070 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 MAXI J1820+070 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 MAXI J1820+070

In research: MAXI J1820+070 appears in science 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 MAXI J1820+070 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: MAXI J1820+070 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Low-mass X-ray binaries, Microquasars, Objects with ASASSN designations, so understanding it makes those chapters shorter.
In everyday life: Look for MAXI J1820+070 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 MAXI J1820+070 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what MAXI J1820+070 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 MAXI J1820+070 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is MAXI J1820+070 in simple terms?

Why does MAXI J1820+070 matter?

Because it connects several science 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 MAXI J1820+070?

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 MAXI J1820+070.