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19th of January 2023
Where are all the supernova remnants?
In an article for The Conversation, Andrew Hopkins describes work that combines data from the ASKAP radio telescope and the Parkes radio telescope, Murriyang, to answer the question: where are all the supernova remnants? A supernova remnant is an expanding cloud of gas and dust marking the last phase in the life of a star, after it has exploded as a supernova. But the number of supernova remnants we have detected so far with radio telescopes is too low. Models predict five times as many, so where are the missing ones? The image above shows the ASKAP (left) and Parkes (right) views of about 1% of the plane of our Galaxy, the Milky Way. In the combination of these images, more than 20 new possible supernova remnants were discovered where only seven were previously known. The resolution of radio-astronomy images depends on the size of the telescope. The Parkes Dish, Murriyang, is 64m in diameter, but the 36 ASKAP dishes are spread over 6km, proving almost 100 times better angular resolution. However, ASKAP's fine resolution but comes at the expense of missing radio emission on the largest scales, which are captured by the Parkes Dish. By combining the information from both Parkes and ASKAP, each fills in the gaps of the other to give us the best fidelity image of this region of our Milky Way galaxy. This combination reveals the radio emission on all scales to help uncover the missing supernova remnants. Astronomers estimate there may be up to 1,500 or more new supernova remnants yet to discover. Solving the puzzle of these missing remnants will open new windows into the history of our Milky Way.

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