Looking at pictures of distant galaxies obtained by the Hubble space telescope, we don't so often think about how beings are born, live and die, these parts of the cosmic web. In 1929, when Edwin Hubble radically changed our view of the Universe, no one can't imagine that mankind will discover a 100 billion galaxies! Astronomer also proved that our expanding with acceleration and was first detailed system of classification of galaxies by shape. Needless to say that this system is the basis of modern classification. Space is a really crazy place, which is born and dies countless number of stars and galaxies, and this process is interconnected: when in the galaxy cease to be born new stars, scientists klassificeret her dead. But why most of the dwarf galaxies dead?
Before Edwin Hubble proved that our galaxy is a speck in the vast cosmic ocean, researchers believed that our galaxy is the whole universe. Moreover, albert Einstein created the General theory of relativity (gr) based on the fact that there was only our galaxy. The discovery shocked him, and he subsequently called Edwin Hubble giant of astronomy. You will agree, completely deserved. So, Hubble has identified three main types of galaxies: spiral, elliptical and irregular. Spiral galaxies as we know today, occur most frequently. But what about their size?
The Researchers note that dwarf galaxies are often satellites of larger, more luminous galaxies. The smallest dwarf galaxies have masses sravnival with a million solar masses. The nearest satellite of our galaxy, the dwarf galaxy called the Small Magellanic Cloud. It is believed that dwarf galaxies has emerged as an independent galaxy billions of years ago, however in space there are more young. Scientists believe that dwarf galaxies should play a greater role in the formation of huge galaxies.
photo by astronomer Edwin Hubble. The man who changed our view of the Universe
Also Important is the fact that like normal galaxies, dwarf contains stars of different ages – just like in normal galaxies; however, the stars in the dwarf galaxies usually have very low contents of chemical elements heavier than helium. Moreover, tiny galaxies also present interstellar gas and dark matter. However not so long ago scientists have discovered as many as 19 dwarf galaxies without dark matter. How this is possible and what it means for modern science .
As you know, the galaxy is considered dead if it no longer forms new stars. But how are they born? Let's start with the fact that in any galaxy there is a gas. Cools, it shrinks and gradually turns into a star. Of course, this is a very simplistic explanation. The force of gravity literally pulls the gas inside the galactic disk and the supernova explosions push it out. It turns out, like galaxy «breathe» gas, inhaling and exhaling it. It is through these processes there are galaxies and new stars are born.
According to the results of a new study of dwarf galaxies very difficult to reconstruct the process of star formation, since most stars in them are very old. Moreover, the existing stars in these galaxies are struggling with the birth of any new stars, even after the Galaxthe IR gets fresh fuel for star formation – gas.
So looking galaxy in the lens legendarnogo the Hubble space telescope
However, a computer simulation developed by the authors of the study showed that eventually the new stars in the dwarf galaxies can arise even give the galaxy brightness. It will just take billions of years. Work can be found on .
The Authors write that in order to collapse into stars, the gas must be cold and dense. This requirement creates problems for small galaxies, which appeared soon after the Big Bang, when ultraviolet radiation of galaxies divided intergalactic hydrogen atoms into protons and electrons. Scientists call this process «reionizatsii» – it allows the radiation to pass through space and heat the gas inside galaxies. The problem is that in dwarf galaxies was originally a little gas, and reionizatsii and completely killed the star formation process. Thus, the researchers write, all the stars in the majority and not the dwarf galaxies are ancient. However, not without exceptions.
Galaxy and the Large and Small Magellanic clouds, satellites of the milky Way
So, two unrelated dwarf galaxy in the constellation Leo, named Leo T and Leo P, still forming new stars. To explain why these small galaxies are flourishing, the study authors resorted to computer modeling of gas, stars and dark matter in dwarf galaxies with low mass. The results showed that infusion of the gas can and start the process of star formation. Just everything is very slow.
Another interesting conclusion of the new study is the fact that now researchers can predict the existence of a new class of galaxies. The simulation shows that some dwarf galaxies already have gas, but the process of star formation has not started yet. Anyway, further studies have to clarify reasons why this is so. I hope from this article you learned something new and amazing about the world in which we live.
Dwarf galaxy is another mystery of the Universe
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