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TOPIC: Calcium Abundance

Blobrana

L

Posts: 131433

Date: Feb 7 04:21 2013

Calcium-48	Permalink

Title: Electron-capture supernovae as origin of 48Ca Authors: Shinya Wanajo, Hans-Thomas Janka, Bernhard Mueller We report that electron-capture supernovae (ECSNe), arising from collapsing oxygen-neon-magnesium cores, are a possible source of 48Ca, whose origin has remained a long-standing puzzle. Our two-dimensional, self-consistent explosion model of an ECSN predicts ejection of neutron-rich matter with electron fractions Ye = 0.40-0.42 and relatively low entropies, s = 13-15 kB per nucleon (kB is the Boltzmann constant). Post-processing nucleosynthesis calculations result in appreciable production of 48Ca in such neutron-rich and low-entropy matter during the quasi-nuclear equilibrium and subsequent freezeout phases. The amount of ejected 48Ca can account for that in the solar inventory when we consider possible uncertainties in the entropies or ejecta-mass distribution. ECSNe could thus be a site of 48Ca production in addition or alternative to a hypothetical, rare class of high-density Type Ia supernovae. Read more (121kb, PDF) __________________

Blobrana

L

Posts: 131433

Date: Feb 6 12:21 2007

Calcium Abundance	Permalink

The universe contains one and a half times more calcium than previously assumed. This conclusion was drawn by astronomers of the SRON Netherlands Institute for Space Research, after observations with ESA's XMM-Newton X-ray observatory. This research offers scientists new insights in the formation history of the elemental building blocks of the cosmos in which supernovae play a crucial role. The iron in our blood, the oxygen we breathe, the calcium in our bones, the silicon in the sand box, all the atoms we are made of are released during the violent final moments of massive stars in the act of dying. These so-called supernova explosions eject newly made chemical elements into space where they become the building blocks for new stars, planets, or even life. However, many questions concerning the very formation of elements and the way they get distributed across the universe still remain open. Read more Read more (269kb, PDF) __________________

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