David Lorenz (Center for Climatic Research, University of Wisconsin-Madison) has released an update of his global #LightPollution maps based on the 2001 World Atlas of the Artificial Night Sky Brightness, recalculated using 2022 VIIRS-DNB data.
Looking closely at the NIRCam image, we see orange- and pink-colored filaments. These are knots of gas ejected from the star itself. Some of them are tiny — less than 100 times the distance between the Sun and the Earth. This suggests the star shattered like glass when it exploded.
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https://webbtelescope.org/contents/media/images/2023/149/01HGGZDJX7RZR07HWZ6YEQ74CR
Cas A's light echo was first discovered in infrared light by the Spitzer Space Telescope in 2005. Later observations by Spitzer show the flash moving through the filamentary gas and dust in the area around the supernova remnant (the remnant is the small circular feature in the center).
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Follow-up observations looked at the visible light echo from light reflecting off of the dust. The light traveled to these distant dust clouds and was reflected back, creating a ~340-year delay. This allowed researchers to recover a spectrum of the original explosion, letting us know that Cas A was a Type IIb supernova — a massive star that lost most of its outer layers before exploding.
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https://ui.adsabs.harvard.edu/abs/2008Sci...320.1195K/abstract
Cassiopeia A is the youngest supernova remnant known in the Milky Way and a unique laboratory for supernova physics. We present an optical spectrum of the Cassiopeia A supernova near maximum brightness, obtained from observations of a scattered light echo more than three centuries after the direct light of the explosion swept past Earth. The spectrum shows that Cassiopeia A was a type IIb supernova and originated from the collapse of the helium core of a red supergiant that had lost most of its hydrogen envelope before exploding. Our finding concludes a long-standing debate on the Cassiopeia A progenitor and provides new insight into supernova physics by linking the properties of the explosion to the wealth of knowledge about its remnant.
El decrecimiento empieza por reivindicar el fin de la obsolescencia programada y el derecho a reparar.
(se empieza por ahí, luego hay que desmantelar el sistema de producción capitalista)
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