Saturday, September 11, 2021

400 years later, Kepler's Supernova debris continues at high speed!

 416 years ago, light from the supernova SN 1604 (or Kepler's Supernova), first observed by the celebrated astronomer Johannes Kepler, reached Earth.  Today, we know that this supernova continues to expand and doesn't seem to have lost speed: with the Chandra X-ray telescope, astronomers have been able to observe and record materials moving at speeds above 30 million km/h where the star exploded - a speed so high that it is 25,000 times faster than the speed of sound.  The article with the study's conclusions was published in the Astrophysical Journal.

 For the study, the researchers tracked the speed of 15 “knots” formed by the debris of what was left of SN 1604 glowing in X-ray emissions.  Until then, the average speed of these knots was about 10 million kilometers per hour;  however, there are nodes observed in the survey at a speed of nearly 40 million kilometers per hour, while the explosion wave continues to expand at nearly 24 million kilometers per hour.  Alone, these results are already able to confirm the discovery of nodes traveling at very high speeds in the remnants of Kepler's Supernova.

 To find out the speed of the knots, the researchers analyzed the X-ray spectrum of the Chandra telescope.  Thus, they identified the intensity of X-ray emissions at different wavelengths, with data obtained in 2016. Then, they compared the wavelengths of characteristics of the X-ray spectrum with laboratory values, and measured the speed of each knot up to Chandra's viewpoint.  With the combined measurements, the team got an estimate of the node's true velocity in three-dimensional space.

 For now, 15 knots is still not enough for scientists to confirm whether the formation continues to expand towards us or if it is moving away, so further observations will be needed.  Even after so long, it's still not clear what's causing this material to move so fast;  some scientists suggest that the remnants of Kepler's Supernova are from a Type Ia supernova, which is extremely powerful.  Another explanation may lie in the environment surrounding these debris, which may allow some of them to move to regions of low density and thus not suffer deceleration.

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