In our last article on Cartwheel Galaxy facts, we learned about its discovery, location and formation. What we didn’t mention is what really happened to the smaller galaxy that collided with it some 200 million years ago. We also didn’t mention why Cartwheel Galaxy is one of the strongest X-Ray sources in deep space. We will learn about those Cartwheel Galaxy fun facts in this article. It is going to be small and quick! Let’s begin…
Cartwheel Galaxy Fun Facts: 1-5 | What happened to the small galaxy?
1. The smaller galaxy which collided with the Cartwheel Galaxy (when it is originally a spiral galaxy) went past to the other side straight through the Cartwheel Galaxy.
2. Scientists say that one of the two smaller galaxies that we see nearby is the intruder galaxy that passed through after a nearly head-on collision.
3. Most likely, the smaller galaxy which passed through Cartwheel Galaxy is the smaller bluer galaxy because it appears disrupted.
4. Not just disrupted, that galaxy also have young blue stars and has evidence of formation of new stars, making it a strong contender for being the intruder galaxy.
5. However, it doesn’t mean that the other one which is not bluish and is actually yellowish may be the intruder. The possible hypothesis is that when it passed through the Cartwheel galaxy, the intruder was stripped off it gas and hence, no new star forming activity.
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Cartwheel Galaxy Fun Facts: 6-10 | Why is the Cartwheel Galaxy an X-Ray source?
6. The Cartwheel Galaxy is a starburst galaxy. It is so called because new stars are being formed in great numbers.
7. Starburst galaxies usually have enormously large new stars that are extremely luminous. However, when these stars come to an end of their life, they explode in what we called supernova explosion.
9. Usually these black holes and neutron stars have companion stars. However, because the black holes and neutron stars have immense gravity, they rip off matter from the companion stars.
10. The immense gravity of the black holes and the neutron stars lead to creation of accretion discs around them.
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Cartwheel Galaxy Fun Facts: 11-15 | Why is the Cartwheel Galaxy an X-Ray source?
11. The accretion discs are actually formed by the matter that has been stripped from the companion stars.
12. When the stripped off materially falls into the immensely powerful gravitational fields of the neutron stars or black holes, powerful X-Rays are emitted.
13. Interestingly, the Cartwheel Galaxy has large number of such black holes in what are known as binary systems.
14. Astronomers have discovered at least one dozen X-Ray sources in Cartwheel Galaxy. Usually, one of two are found in galaxies.
15. There is another type of X-Ray source in Cartwheel Galaxy. The X-Rays are also emitted by supernova remnants and young supernovas. Both sources produce X-Rays that are either hyperluminous or ultraluminous X-Rays (represented as U/HLXs).
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Cartwheel Galaxy Fun Facts: 16-20 | Good to know facts
16. Here is something interesting. The bright blue ring that we see in Cartwheel Galaxy has always been (historically) thought to be galaxy’s outermost boundary.
17. The diameter of the ring is 150,000 light years, making the galaxy slightly bigger than our Milky Way Galaxy.
18. This notion is changing. A recent study (by GALEX space telescope) has revealed that beyond the blue ring there is another ring, which has twice the diameter of the blue ring. This ring is really faint and hence, difficult to see.
19. However, if that size of the newly discovered outer ring is taken into consideration, the Cartwheel Galaxy becomes 2.5 times the size of our Milky Way Galaxy. This means that our very own galaxy can nicely fit inside it.
20. The bright blue ring of the Cartwheel Galaxy that we see is home to several billion stars. There are far more in the entire galaxy.
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About the above image taken by GALEX space telescope:
1. The yellow-orange inner ring and the galaxy’s nucleus represent a combination of infrared light and visible light.
2. The red color spread throughout the galaxy represents organic matter that are illuminated by nearby star formation of low level.
3. The green represents the older and less-massive stars with visible light.
4. The blue represents areas of super massive stars about 5 to 20 times as big as our own Sun.
5. Pink represents area where UV rays and X-Rays are superimposed.