Enthusiasts of Marvel movies and comics might recognize the tale of Thor’s Hammer, Mjolnir. This metal was crafted from the core of a dying star. While the power of the God of Thunder is not accessible to anyone, some of the heavy metals around us might originate from a long-dormant planet.
Similar to living beings, stars experience a life cycle. For stars with less than about 10 times the mass of the sun, the concluding phase is a White Dwarf. At this point, stars are compressed to the density of Earth and reach temperatures of around 100,000 Kelvin, approximately 100,000°C or 180,000°F. Unlike other stars, they cease to fuse elements in their cores for energy. Instead, they maintain their structure through Quantum mechanical principles and slowly release heat. This is why scientists often refer to white dwarfs as The dead star.
Nevertheless, under certain conditions, a white dwarf can experience one last surge of energy. There exists a limit to a white dwarf’s size, specifically 1.4 times the mass of the sun. If a star exceeds this threshold, gravitational forces can overpower its structural support, caused either by accumulating surrounding gas and dust or by merging with another white dwarf. This rapid compression ignites a chain reaction of fusion, culminating in an explosion known as a Type IA Supernova. Researchers estimate that such an explosion occurs in the Milky Way every 100-700 years.
A group of astrophysicists aimed to explore this phenomenon along with a rarer alternative. If a star is spinning while accumulating material, it can collapse into something even denser, a Neutron Star, and eject excess material without undergoing an explosion. The team simulated the aftermath of six different scenarios where the white dwarf collapsed after surpassing the size limit, known as Post Bounce. In these simulations, they adjusted various parameters, such as speed, width, temperature, and size thresholds of the white dwarfs.
They then controlled the initial conditions, including the mass of the white dwarf. Alkar simulated the behavior of low-energy particles referred to as liquid physics Neutrino 2D. Given the computational demands, astrophysicists typically simulate only a fraction of a second of post-bounce behavior. However, this team extended their simulation to 4.5-7 seconds to gain a deeper understanding of how ejected layers from white dwarfs behave.
The simulated white dwarf quickly collapsed, transitioning from a slower rate of 0.8 seconds to a rapid 0.04 seconds. The scenario diverged, with the unspinning white dwarf erupting into a supernova, while the spinning white dwarf transformed into a neutron star. In this latter case, the remnants of the stars were so densely packed that neutrinos collided with them, heating them up and ejecting them from the star.
The focus then shifted to the ejected material. The mass of material expelled ranged from 0.005 times to 0.05 times the mass of the sun, equivalent to about 1,700 to 17,000 Earth masses. Heavier elements like nickel can form during this process.
The researchers concluded that the outer layers ejected from collapsing white dwarfs could change rapidly during these events. They discovered that the material released was initially rich in protons and formed lighter elements but later became enriched in neutrons and heavier elements.
The team recommended developing more advanced 3D models of white dwarfs prior to their collapse for future studies. They suggested that astrophysicists could utilize these models to estimate the contribution of elements in the solar system originating from white dwarf collapses.
Post view: 78
Source: sciworthy.com
