- The Milky Way Galaxy and the Andromeda Galaxy (M31) will begin colliding in another 5 billion years. The closing velocity between us is 70 miles per second. Yet, we are still 2.5 million lightyears apart. We can witness today what happens when galaxies collide. If you want a preview there are several in the works right now.
- The Antenna Galaxy, Arp 273 Galaxy, and M82 Centaurius A Galaxy are three examples. We think of collisions from meteors and asteroids and comets hitting planets and moons. But, it is hard to imagine what it would be like when stars collide. For one reason we have never seen such an event. Our Sun lies about 5 lightyears from the nearest other star. So, we can not likely see a collision with our neighbor stars with that much separation.
- What would it be like when galaxies collide and billions of stars are passing each other? Galaxies are typically 100,000 lightyears across and only separated by 1,000,000 lightyears. The separations are only 10 times the galaxy disk diameters. Therefore, galaxy collisions are expected to occur much more often than star collisions. Its ironic that stars almost never collide but galaxies regularly do. Every galaxy is likely to go through at least one collision during its lifetime.
- The Antenna Galaxies are 45 million lightyears away. NGC-4038 and NGC-4039 are spiral galaxies that have been colliding for the past 300,000,000 years. The telltale collision is visible in the tidal tails of gas and dust surrounding the galaxies. The cores of the two galaxies narrowly missed each other. They are now swinging around for another pass. They will collide again in another 400,000,000 years. Eventually the two spiral galaxies will merge into a giant elliptical galaxy.
- Merging galaxies merely pass through each other with their stars never ever touching. However, the interstellar gas will be whipped up into giant clouds. Some of the clouds will be the birthplaces for new stars. Billons of stars could form simultaneously creating giant blue superstar clusters amongst the colliding galaxies.
- See the image of the Antenna Galaxy. The blue spots are baby stars, the red spots are regions of ionized hydrogen gas. The yellow orange blobs are the cores of the two galaxies. What we can see in this image is only 20% of what is there. At least 5 times more material surrounds the galaxies in the form of Dark Matter.
- The M81 and M82 galaxies were first seen in 1774 . They are ½ way in between Polaris, the North Star, and the Big Dipper. They are 12,000,000 lightyears away. M82 is a long cigar shaped galaxy that resembles a galaxy seen edge-on. 600 lightyears from M82’s center are intense X-ray emissions coming from a Blackhole that is 200 to 5,000 Solar Mass. If you are looking through an infrared telescope M82 is the brightest thing you can see in the Universe.
- To make sense of the image of the 2 galaxies M81 and M82 they must be gravitationally whirling around each other and through each other in a giant galactic collision. Today there are 130,000 lightyears separating them, but, that is the width of one galaxy. It is estimated that the cores passed each other about 200,000,000 years ago. The collision has resulted in a star nursery where stars are being born at 10 times the rate of our galaxy.
- Only about one out of 100,000 galaxies in the Universe have been cataloged or given any kind of reference number. Within a billion lightyears of us there are at least 3,000,000 large galaxies. Within 100,000,000 lightyears of us there are at least 2,500 large galaxies. In addition, there are another 50,000 Dwarf Galaxies.
- Another colliding galaxy is the Centaurus A Galaxy that is the fifth brightest galaxy in the Southern Hemisphere. It was discovered in 1826 and was identified as NGC-5128 in 1949. When it was discovered it was identified as a powerful radio source. In 1970 astronomers found that it was also a powerful X-ray and Gamma Ray source, and a powerful infrared source. What is causing all of this? A super massive Blackhole?
- Yes, Centaurus A is the merger of a giant elliptical and a giant spiral galaxy. The Blackhole’s accretion disk at the center is emitting X-ray jets and solid particles that are traveling ½ the speed of light. The galaxy is receding away from us at 300 miles per second. The merger likely started about 200,000,000 years ago.
- The next merger is called the “ Rose Galaxy”. It is Arp273 and 300,000,000 lightyears away where 2 galaxies are in a merger that started 200,000,000 years ago. UGC-1813 and UGC-1810 are both spiral galaxies. Their spiral arms today are full of hot, new , blue stars. In another 500,000,000 years the 2 spirals will have merged into on single elliptical galaxy.
- The Rose Galaxy image has orange blobs that are the cores of the 2 galaxies. The visible part of this image is only 20% of the material that is actually there. At least 5 times more material in the form of Dark Matter surrounds the 2 galaxies. All of these galaxy mergers are seen as massive destruction. But, in this destruction of structure there is a creation of new stars. Even the Cosmos appears to have a circle of life. An announcement will be made shortly, stay tuned.
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707-536-3272, Friday, November 11, 2011
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