science

LP 944-20

LP 944-20 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 LP 944-20 rather than just read about it. In short: LP 944-20 is a dim brown dwarf of spectral class M9 located 21 light-years from the Solar System in the constellation of Fornax. With a visual apparent magnitude of 18.69, it has one of the dimmest visual magnitudes listed on the RECONS page.

Key takeaways

LP 944-20 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect LP 944-20 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of LP 944-20 from memory before moving on to harder problems.

Reference excerpt

LP 944-20 is a dim brown dwarf of spectral class M9 located 21 light-years from the Solar System in the constellation of Fornax. With a visual apparent magnitude of 18.69, it has one of the dimmest visual magnitudes listed on the RECONS page. In infrared wavelengths, is one of the brightest brown dwarfs, if not the brightest at JMKO=10.68±0.03 mag.

Discovery LP 944-20 was discovered in the Luyten-Palomar Survey. It appears as a star with R=17.5 mag with a proper motion of 334 mas/yr in a catalog from 1979. It was however first published in 1975 by Luyten & Kowal. It was re-discovered in the APM survey, a quasar survey, in which the red color was noticed. The first spectrum was published in 1997 by Kirkpatrick, Henry & Irwin. A spectral type of M9 or later was assigned in this work and a distance of around 5 parsec was established thanks to the parallax being measured. In 1998 Tinney discovered that this M-dwarf shows the 6708 Å Lithium absorption line and H-alpha emission line, which helped to constrain the age to around 500 million years and established it as a brown dwarf with a mass of around 60 MJ.

Physical characteristics Short after LP 944-20 was established as a brown dwarf, the fast rotation was detected in 1998. Later a work in 1999 claimed to have detected variability in LP 944-20. A search for dust around LP 944-20 has shown that it has no disk. Due to short rotational period, this young brown dwarf is displaying strong and frequent X-ray flares, and possessing a strong magnetic field reaching 135 G at the photosphere level. On 15 December 1999, an X-ray flare was detected. On 27 July 2000, radio emission (in flare and quiescence) was detected from this brown dwarf by a team of students at the Very Large Array. Observations published in 2007 showed that the atmosphere of LP 944-20 contains much lithium and that it has dusty clouds. A search for planets was carried out in 2006 using the radial velocity method. No planets were found, but variability with an amplitude of 3.5 km/s was detected. This variability is likely due to weather effects and the rotation of the brown dwarf. In 2015 high resolution Doppler images were taken of LP 944-20 and GJ 791.2A. The time series spectra show line profile distortions, which were interpreted as starspots. These starspots were reconstructed and found to be concentrated at high latitudes. The modelling produces a better fit of ΔT=200 K (−73 °C; −100 °F) between starspots (Tspot=2,100 K (1,830 °C; 3,320 °F)) and photosphere (Tphot=2,300 K (2,030 °C; 3,680 °F)). In a large program in 2016 the spectral type was established to be M9β in the optical and L0β in the infrared. The beta stands for a surface gravity intermediate between normal and low. The mass was calculated to be 29.62±16.67 MJ. Observations with TESS found that LP 944-20 is variable with a period of around 3.8 hours and an amplitude of 1760±100 ppm. This is in agreement with previous estimates of a period of less than 4.5 hours.

References

External links "The 100 nearest star systems", Research Consortium on Nearby Stars

Illustrations

Worked examples

Example 1 — a first encounter with LP 944-20

Start with the simplest possible case. Write down what LP 944-20 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 LP 944-20 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 LP 944-20 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 LP 944-20

In research: LP 944-20 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 LP 944-20 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: LP 944-20 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Fornax, M-type brown dwarfs, X-ray emitting brown dwarfs, so understanding it makes those chapters shorter.
In everyday life: Look for LP 944-20 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 LP 944-20 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what LP 944-20 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 LP 944-20 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is LP 944-20 in simple terms?

Why does LP 944-20 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 LP 944-20?

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 LP 944-20.