The Cartwheel is located about 400 million light-years away from Earth and is one of my favorites. It is the same size as the Milky Way. Its resemblance to our house ends there.
You may know about ellipticals, spirals, and irregulars, but there is a small class called peculiar: Galaxies that have an overall shape. The Cartwheel is similar to a cartwheel.
It is uncommon for an object to have a nickname that hits the mark.
There is a new image of the Cartwheel, and it is amazing. It is a combination of images taken by two different cameras.
The strange structure of the Cartwheel is thought to have been caused by a collision hundreds of million of years ago. It was a bullseye, as the smaller one passed through the center of the bigger one at high speed. The larger galaxy created a ring of gas and stars similar to a rock being dropped into a pond.
The outer ring was created by expanding outward and riling up the center of stars in the big spiral. After the collision, the gas and stars in the disk of the bigger spiral were piled up into thin lanes, creating the "spokes" you can see. Astronomers created a series of animations which you can see on their website if you are interested. Our understanding of the collision has changed, but these will show you what happened.
Blue, green, yellow, and red are the colors of the NIRCAM images, which cover the wavelength range of about 0.9 microns. As the gas clouds in the outer ring compressed and formed new stars by the millions, this shows older stars and the glow of dust from newborn stars.
It is possible for MIri to see farther into theIR. In the first image that is shown in shades of orange, there is a combination of MIri images on its own.
The blue wavelength is well out into the thermal IR, where warm objects glow. You have a peak brightness of about 10 microns. It's just so.
Betelgeuse, a cooler red supergiant, is an exception because stars in visible light aren't very bright at these wavelength. There are tiny grains of silicates, or rocky material, and long chains of carbon molecule called PAHs. They are basically soot, so think of them that way.
In 2020 when Betelgeuse dimmed so much it blew a huge cloud of dust into space that partially obscured our view of it. Dust can be seen in visible light, but in thermal IR it glows. That is what MIri finds.
There are clumps of dust in the inner ring where star formation creates massive stars that burn through their fuel in only a few million years and turn into red supergiants. Dust was created when the stars exploded as supernova. Dust lanes are formed in spiral galaxies when clouds of dust collide, but in the Cartwheel's outer ring it forms huge clumps. The idea that a recent supernova was found in the outer ring makes sense.
The spokes have a lot of dust, created by stars that formed from gas compressed there, and it is1-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-6556
Where is the alien universe? You might think that it is one of the two small galaxies on the left, but they are not, they are part of a small group. There is a third nearby galaxy that is not seen in this section of sky. It can be seen in wider images, and in fact radio observations show the two are connected, a tail of debris left after the collision.
The Cartwheel is one of my favorite things. Astronomers will be able to figure out what happened there. We know a lot about how colliders work, but they are not the same. The more we observe, the better we will be at probing what happened before, during, and after these massive train wrecks.
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