Single Hubble Image Captured Supernova At Three Different Times

John Timmer writes via Ars Technica: Over the last few decades, we've gotten much better at observing supernovae as they're happening. Orbiting telescopes can now pick up the high-energy photons emitted and figure out their source, allowing other telescopes to make rapid observations. And some automated survey telescopes have imaged the same parts of the sky night after night, allowing image analysis software to recognize new sources of light. But sometimes, luck still plays a role. So it is with a Hubble image from 2010, where the image happened to also capture a supernova. But, because of gravitational lensing, the single event showed up at three different locations within Hubble's field of view. Thanks to the quirks of how this lensing works, all three of the locations captured different times after the star's explosion, allowing researchers to piece together the time course following the supernova, even though it had been observed over a decade earlier. [...] By checking that Hubble data against different classes of supernovae that we've imaged in the modern Universe, it was likely to be produced by the explosion of either a red or blue supergiant star. And the detailed properties of the event were a much better fit to a red supergiant, one that was roughly 500 times the size of the Sun at the time of its explosion. The intensity of the light at different wavelengths provides an indication of the explosion's temperature. And the earliest image indicates that it was roughly 100,000 Kelvin, which suggests we were looking at it just six hours after it exploded. The latest lensed image shows that the debris had already cooled to 10,000 K over the eight days between the two different images. Obviously, there are more recent and closer supernovae that we can study in far more detail if we want to understand the processes that drive a massive star's explosion. If we're able to find more of these lensed supernovae in the distant past, however, we'll be able to infer things about the population of stars that were present much earlier in the Universe's history. At the moment, however, this is only the second one we've found. The authors of the paper describing it make an effort to draw some inferences, but it's clear those will have a higher uncertainty. So, in many ways, this doesn't help us make major advances in understanding the Universe. But as an example of the strange consequences of the forces that govern the Universe's behavior, it's a pretty impressive one. The findings appear in the journal Nature.

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