Thursday, 20 April 2017

A weird sombrero

Because of its odd shape, M104 (aka the Sombrero Galaxy) has puzzled the minds of scientists for decades. It exhibits a small, very bright core that is home to a supermassive black hole. A spectacular, dark dust lane encircles the galaxy and is already visible in a pair of binoculars. This enormous ring of dust and matter generates most of the galaxy's stellar formation as can be deduced from the many ripples and structures within it. In between, however, there seems to be some sort of void. 

Recent study revealed that this galaxy in fact consists of two galaxies into one. It's still unclear how this came to be but most probably the Sombrero Galaxy's the result of a collision of two more or less equally-sized galaxies. The heart of the Sombrero remained an old, elliptical galaxy. Remember what I told you about the coffe and milk? When you add milk to coffee and stir it, a spiral structure appears and in terms of a galaxy this means that there's a lot of activity going on. But after a while the coffee and milk have mixed completely and the whole becomes a plain, brownish liquid. The galaxy's energy diminishes, the spiral arms disappear and all that's left is a vast cloud of stars: an elliptical galaxy. The cloud of old stars is very well visible here on the sketch. The second galaxy on the other hand was smeared out by centrifugal forces and formed this ring-like structure, just like the famous rings around Saturn. Therefore you get this old galaxy with little star formation activity in the middle and a ring of young, active material around it. 

This galaxy also seems to possess thousands of globular clusters, hovering around the nucleus. These were invisible to me off course, because we're talking about a distance of 28 million lightyears here. Still in our backyard in astronomical terms but imagine the time it took for its light to arrive! 


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