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hubie [soylentnews.org] writes:

An exploded star can pose more risks to nearby planets than previously thought [illinois.edu]:

This newly identified threat involves a phase of intense X-rays that can damage the atmospheres of planets up to 160 light-years away.

[...] Earth is not in danger of such a threat today because there are no potential supernova progenitors within this distance, but it may have experienced this kind of X-ray exposure in the past, scientists say.

Before this study, most research on the effects of supernova explosions focused on the danger from two periods: the intense radiation produced by a supernova in the days and months after the explosion, and the energetic particles that arrive hundreds to thousands of years afterward.

However, even these alarming threats do not fully catalog the dangers in the wake of an exploded star. Researchers have discovered that between these two previously identified dangers lurks another. The aftermaths of supernovae always produce X-rays, but if the supernova's blast wave strikes dense surrounding gas, it can produce a particularly large dose of X-rays that arrives months to years after the explosion and may last for decades.

[...] "The Earth is not in any danger from an event like this now because there are no potential supernovae within the X-ray danger zone," said Illinois undergraduate student Connor O'Mahoney, a co-author of the study. "However, it may be the case that such events played a role in Earth's past."

There is strong evidence – including the detection in different locations around the globe of a radioactive type of iron – that supernovae occurred close to Earth between about two and eight million years ago. Researchers estimate these supernovae were between about 65 and 500 light-years away from Earth.

[...] The study reports that although the Earth and the solar system are currently in a safe space in terms of potential supernova explosions, many other planets in the Milky Way are not. These high-energy events would effectively shrink the areas within the Milky Way galaxy, known as the Galactic Habitable Zone, where conditions would be conducive for life.

Journal Reference: Ian R. Brunton et al 2023 ApJ 947 42

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