In November, NASA celebrates the “month of nebula” – #NebulaNovember. In honor of this “Hi-Tech” talks about the most famous, beautiful and unusual of them.
Nebulae are some of the most popular space objects. This is not surprising – they take on the strangest and most unusual forms. In addition, all nebulae have two names – the official one with letters and numbers, and the second appears as a result of the imagination of scientists who call them based on external similarity.
This first light image from the national telescope TRAPPIST in La Silla shows the Tarantula Nebula, located in the Large Magellanic Cloud (LMC), one of the nearest galaxies to us. Photo: ESO
Another of their unusual property is that they can be both traces of the death of a star, and a manger for new luminaries. Space telescopes such as NASA’s Spitzer and Hubble have captured many images of distant nebulae. And this is what the most famous of them look like.
What kind of nebula are there?
Nebulae are giant clouds of dust and gas in interstellar space. Some are caused by gas and dust ejected by the explosion of a dying star, such as a supernova. Also, nebulae are regions where new stars begin to form. For this reason, some nebulae are called “stellar nurseries.” They are composed of dust and gases, mainly hydrogen and helium. Dust and gases in the nebula are widely spaced, but gravity brings them closer together. As these clumps get larger, their gravity increases between them. In the end, the clump of dust and gas grows so much that it collapses under the influence of its own gravity. The collapse causes the material in the center of the cloud to heat up – a star emerges from this hot core.
Another interesting type of nebula is planetary. In fact, these are huge ionized shells of gas that surround a hot compact star, a white dwarf. Formed when the outer layers of a red giant or supergiant are ejected at the final stage of evolution. They look like light spots of a round shape with small angular dimensions, visible in the starry sky. Their peculiarity is that they live very little (by astronomical standards). This phenomenon lasts only a few tens of thousands of years. For example, the closest to Earth – the Helix Nebula (NGC 7293) is located 650 to 700 light years from Earth – planetary. It is important to note that such nebulae have nothing to do with planets – this is, rather, a historical incident. The first planetary nebulae were discovered at the end of the 18th century, and in the eyepieces of telescopes of that time they appeared as a rounded nebula, resembling a planet. Hence the name.
The largest nebula
The nebula record holder is NGC 2070, an emission nebula in the constellation Dorado. Also known as Tarantula. It belongs to the Milky Way’s satellite galaxy, the Large Magellanic Cloud. She is an example of a “stellar nursery”, is a vast area of ionized hydrogen, where the processes of active formation of stars take place.
For example, in the center of the nebula there is a small cluster R136, the age of the stars in it is about 2 million years. In addition, the nebula contains the supermassive star R136a1, which weighs as much as 315 Suns.
The very “first” nebula
The gaseous Crab Nebula NGC 1952 lies in the constellation Taurus. It is 6,500 light years distant from Earth. Its peculiarity is that it became the first number in the list of space objects compiled by the French astronomer of the 18th century Charles Messier. At the same time, then he did not yet know that NGC 1952 is the remnant of a supernova explosion, which was observed by Chinese astronomers back in 1054 AD. NS. Inside it is the pulsar PSR B0531 + 21 – a young neutron star and a supernova remnant SN 1054. The object is about 25 km in diameter and rotates 30 times per second, or one revolution every 33 milliseconds.
The Crab Nebula is a gaseous nebula in the constellation Taurus, which is a supernova remnant SN 1054 and a plerion. The nebula was first observed by John Bevis in 1731.
Like other nebulae, it emerged after a supernova explosion. But, unlike them, it is a plerion. This means that it is powered by the PSR B0531 + 21 pulsar, or rather the wind, its wind.
Most popular nebula
The Eagle Nebula has given mankind one of the most famous astrophotographs – “Pillars of Creation”, the region where new stars are born.
None of the photographs that Hubble took and which were shown to the public generated such a stir. At the same time, the “Pillars of Creation” is not an object, it is just a tiny piece of nebula, which made the Hubble Telescope famous. This is also an active star-forming region and a star cluster, so the name is quite consistent. Moreover, the pillars themselves are voids in interstellar gas and dust. They were formed by newly born stars – the 4 brightest stars in the cluster.
The Pillars of Creation are clusters of interstellar gas and dust in the Eagle Nebula, about 7,000 light-years from Earth, first captured in photographs by the Hubble Space Telescope.
The most amazing thing is that the “Pillars of Creation” are still visible, but no longer exist. According to another space telescope, the infrared Spitzer, a supernova exploded behind the Eagle Nebula about 6,000 years ago. The hot cloud of dust and gas expanded and destroyed the “pillars”. At the same time, the nebula is located at a distance of 7,000 years ago, which means that earthlings for another thousand years will be able to observe the “Pillars of Creation”, which have long been destroyed.
The most popular photo of “Pillars of Creation” was taken in visible light. A new image from NASA shows it in infrared light, which passes through clouds of cosmic dust and gas, revealing more details from the depths of space. In this view, the background of the image is dotted with distant stars, which, among other things, form inside the “Pillars”. Their outlines remain subtle.
Nebulae are some of the most beautiful objects in the night sky. Initially, this was the name for any extended astronomical objects in which it was not possible to distinguish stars. With the development of telescopes, the term has narrowed to refer only to areas of cosmic dust, gas, and plasma that absorb or emit light. Perhaps in the future, our definition of nebulae will change again.
