Questions around the nebula!

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2022-07-23 07:18:46

Nebula is a Latin word for “cloud”, but in astronomical contexts it refers to any celestial body that looks like a cloud when viewed through a telescope.

In the past, when telescopes were not as modern and powerful as they are today, the term also referred to galaxies like Andromeda – our neighbour, and it was often called the “Andromeda Nebula”.

However, with the advancement of modern telescopes, we know that galaxies are not like and are not clouds at all, instead they are made up of billions of stars. This means that astronomers currently only use the name “nebula” for the “genuine” clouds – consisting of gas and dust – located inside the galaxy.

Where is the nebula located?

Nebulae are commonly found in interstellar space, and are also known as the interstellar medium. On average, this region contains only about one atom per cubic centimeter. In some places, however, the densities can be significantly higher than this —high enough to be seen through a telescope and also one of the most interesting points in the field. field of astronomy. In fact, most of the images of nebulae we know today were taken by the Hubble telescope, such as the “Pillars of Creation”.

Space Puzzle: Questions Around the Nebula!  - Photo 2.

Pillars of Creation.

According to data collected from space, we know there are several different types of nebulae, depending on how they form and their composition. Most nebulae are mainly formed from gas, which can glow with its own light, creating the colorful shapes we seem to be familiar with.

But other nebulae —such as the so-called “dark nebulae” —are composed mainly of cosmic dust, and instead of glowing, this dust acts to block light from objects beyond it.

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Relationship between nebulae and stars

Nebulae play an important role in the life cycles of stars, both as they are born and as they die. Stars are born in dense clumps of gas, dust, and other matter within diffuse emission nebulae, and these nebulae are often referred to as “stellar nurseries”.

The Pillars of Creation taken by Hubble is also a nebula of this kind, in addition to the rather famous Orion nebula ⁠— you could have seen this nebula yourself through a civilian telescope if you knew how. .

The main force at work here is gravity, which causes the interstellar medium to continuously condense into a nebula, and gravity causes the masses within the nebula to collapse into stars.

At the end of a star’s life, we often encounter another type of emission nebula. Stars like the Sun, at the end of their lives, will often turn into white dwarfs. But before turning into white dwarfs, they will release huge clouds of gas and form what are known as “planetary nebulae”.

Unlike diffuse emission nebulae, these nebulae have a more defined shape, usually circular. And it was because of this that British-German astronomer William Herschel mistook them for planets when he first observed them in the 1780s.

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A spectacular image from Hubble reveals the massive “star nursery” in the 30 Doradus Nebula.

However, not all stars end their life cycles so smoothly and peacefully. When a star is much more massive than the Sun, at the end of its life it will explode as a supernova, and the debris from that explosion will form a kind of nebula. another is called a supernova remnant. The most famous of these is the Crab Nebula, which was noted by Chinese and Arab astronomers in 1054.

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To capture colorful images of the nebula, telescopes – such as the Hubble Space Telescope and the James Webb Space Telescope (JWST) have used the very infrared radiation emitted by the nebula. out to record images.

Visible light emitted by stars forming in and around the nebula can be blocked by the dense clouds of cosmic gas and dust that make up the nebula. Therefore, scientists must look for other wavelengths of light emitted by the nebula, such as infrared radiation.

Using the Near Infrared Camera (NIRCam) and the Mid-Range Infrared Instrument (MIRI), JWST captured one of the most detailed images of the nebula. In the two images above, JWST captured the layers of gas and dust inside the Southern Ring Nebula. Each layer has been created by the expulsion of cosmic matter from the central dying star.

Reference: Space

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