astronomy

N119

N119 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 N119 rather than just read about it. In short: N119 (formally known as LHA 120-N 119) is a spiral-shaped H II region in the Large Magellanic Cloud. Its dimensions are large, at 131 x 175 pc (430 × 570 ly).

Key takeaways

N119 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect N119 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of N119 from memory before moving on to harder problems.

Reference excerpt

N119 (formally known as LHA 120-N 119) is a spiral-shaped H II region in the Large Magellanic Cloud. Its dimensions are large, at 131 x 175 pc (430 × 570 ly). It contains several luminous stars including S Doradus, LH41-1042, and LMC195-1. Its peculiar S-shaped structure is difficult to explain with classical models.

Location

With a right ascension of 5h 18m 45s and a declination of −69° 14′ 03″, this nebula may be found in the constellation of Dorado about 160 kly (50 kpc) away. Its apparent size is roughly 9′ 14″ × 12′ 15″. It lies at the northern side of the Large Magellanic Cloud's stellar bar, 15′ southeast of the center of rotation of the galaxy's neutral hydrogen.

Structure The nebula seems to be in an S-shape, but on closer inspection reveals to have extensions of the spiral arms, ending in a figure 8. The unusual shape may be due to the combination of other nebula, or it may have been formed by perforation of the original molecular cloud by powerful stellar winds and explosions. It may have also formed by a collision of two interstellar clouds, according to Annie Laval and Patricia Ambrocio-Cruz. The gas would have been compressed, forming the luminous stars seen today.

Bubbles

N119 contains several bubble-shaped nebulae: DEM L132a; DEM L132b; DEM L123; and an unnamed WR nebula. In total the nebulosity of N119 spans 131 by 175 parsecs (430 ly × 570 ly). DEM L132a is 88 parsecs across and encompasses the two luminous blue variables S Doradus and R85. However, those stars do not emit sufficient ionising radiation to produce the observed shell, and no other hot luminous stars are seen within the shell. It may have been produced by one or both of the LBVs during an earlier phase of their evolution. DEM L132b is 52 parsecs wide and surrounds two class O giants or supergiants and numerous other hot stars, which comfortably produce the necessary ionising radiation and fast winds to sculpt the bubble from the surrounding interstellar material. The WR bubble nebula is a similar size to DEM L132b and is produced by Brey 21, a binary containing a WN3 star and a B-type supergiant. DEM L123 is 158 parsecs across and its origins are unclear. No sufficiently powerful stars have been detected inside it that could produce it with their stellar wind (as this would require the power of 44 O6 supergiants) and it is ten times too energetic to have originated from a typical supernova. This bubble may have been created by a hypernova.

Observational history N119 was first catalogued by Karl Henize, an American Astronomer, when he made a list of Hα emission-line stars and nebulae in 1956. The full designation is LHA 120-N 119: the 119th nebula on Lamont–Hussey Observatory H-alpha (Lamont–Hussey Alpha) plate 120. Plate 120 covered the Large Magellanic Cloud while plate 115 covered the Small Magellanic Cloud. LHA 120-S 119 is a Wolf–Rayet star in another part of the LMC. There is no LHA 115-N 119 since fewer nebulae were found on the SMC plate. On March 25–26, 1999, The Wide Field Imager, a 67-million pixel digital camera at the MPG/ESO 2.2-m telescope at the La Silla Observatory, took a picture of the nebula with a field of view of 31.49 x 30.64 arcminutes at a RA of 5h 18m 37.89s and a declination of −69° 24′ 23.27″, and orientation of north being 1.9° right of vertical. It did four exposures each in the B band (2 minutes each), the V band (2 minutes each), and the Hα band (20 minutes each). It is available for download on ESO's website at 2,303 × 2,241 pixels.

Luminosity

N119 suffers from 0.20 magnitudes of extinction in the B (blue) band, 0.15 in the V (yellow-green) band, and 0.12 in the Hα (red) band.

NGC 1910

N119 has an associated open cluster called NGC 1910 (also known as ESO 56-SC99). Its apparent magnitude is 11.2 and its apparent size is 1.54 arcminutes. It is inside N119 with a right ascension of 5h 18m 42.5s and a declination of −69° 14′ 12.1″.

Notes

References

External links Original image

Illustrations

Worked examples

Example 1 — a first encounter with N119

Start with the simplest possible case. Write down what N119 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 N119 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 N119 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 N119

In research: N119 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 N119 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: N119 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Dorado, H II regions, Large Magellanic Cloud, so understanding it makes those chapters shorter.
In everyday life: Look for N119 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 N119 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what N119 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 N119 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is N119 in simple terms?

N119 (formally known as LHA 120-N 119) is a spiral-shaped H II region in the Large Magellanic Cloud. Its dimensions are large, at 131 x 175 pc (430 × 570 ly).

Why does N119 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 N119?

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 N119.