When the European Space Agency’s XMM-Newton pointed its telescope at two unidentified sources of light in the outskirts of the Large Magellanic Cloud, scientists were able to confirm what seemed an unlikely discovery. They found two supernova remnants in the far reaches of our neighbouring galaxy.
The two objects that XMM-Newton looked at are shown as the two circles in the lower left of this visible-light image of the Large Magellanic Cloud: J0624-6948 (orange, higher in the image) and J0614-7251 (blue, lower in the image). The yellow crosses represent supernova remnants that had been found before.
It is surprising that these two sources of light turned out to be supernova remnants, far away from all other echoes of stellar explosions that we knew of before. Scientists believe, that for the shock of a supernova to leave such an imprint on its surroundings, the dying star must be in an environment that is dense enough with charged particles (ionised gas). This is not usually the type of gas we find so far in the outer reaches of a galaxy.
This is one of the new things we can learn from XMM-Newton’s discovery: The environment around the Large Magellanic Cloud is made up of more electrically charged gas than we would expect. The reason for this likely lies in how the galaxy is interacting with the Milky Way and the Small Magellanic Cloud. In this way, these two supernova remnants are helping us to better understand the dynamics of our home galaxy’s neighbourhood.
XMM-Newton observed the two remnants in three different types of X-ray light. This resulted in the three colours (yellow, purple and blue) in the images that appear when clicking on the two circles. They give an indication of the chemical elements that are most common in different parts of the remnants.
The yellow colour that is for example dominant in the centre of J0614-7251 tells us that this part of the supernova remnant is made up mostly of iron. This clue allowed scientists to classify this remnant for the very first time as the result of a Type-Ia supernova. This was possible because the new image by XMM-Newton shows enough detail to distinguish the inner circle and outer ring of the remnant clearly enough.
Find the scientific paper about this discovery here.
[Image Description: A vast sea of speckles of stars against a faded black background. In the centre of the image, the stars cluster to form a bright and dense green cottoncandy-colored haze, that is the Large Magellanic Cloud. Scattered across the middle of the image are about 50 small yellow crosses, some of them are so close to one another that they almost overlap. In the lower left quarter of the image, two circles were drawn that lay wide apart: an orange circle towards the horizontal middle of the image, and a blue one to the lower right of it.]