ASTR0880 – 3D rad-hydro simulations of the outflows of evolved stars

Allocation: 1/17/2023 – 6/17/2023
Domain Area: Astronomy
PI: Prof Shazrene Mohamed
Active: 5
CPUs used: 59821/500000 (11.96%)
Press Release

Energetic explosions are a common occurrence in the universe. With new and upcoming
observational facilities, we will be able to detect millions of these events
in the night sky; we thus need a way to distinguish them from one another.
The events range from dying stars exploding as supernovae, to the exciting
and now well-known neutron star mergers that led to the detection of
gravitational waves in 2015.  In this
work, we focus on another type of explosion – those produced by collisions
between stars. Just as big cities have greater traffic than cities in the
countryside, some regions in space have a larger number of stars in a
relatively small volume. In these regions, e.g., the centers of galaxies and
globular clusters, the high concentration of stars increases the probability
for collisions. We investigate specifically the collisions between
main-sequence stars and white dwarfs. Main-sequence stars are average stars
similar to the Sun and consist primarily of hydrogen and helium with small
amounts of heavier elements such as carbon, nitrogen and oxygen. White dwarfs
are produced when stars at the end of their lives (billions of years old)
shed their outer envelope and leave behind a core consisting of carbon and
oxygen. White dwarfs are more exotic than the Sun, since they can weigh about
half the mass of our sun, whilst squeezing all that mass into 2% of the
Sun’s radius – roughly the size of the earth. This implies that these
objects have extreme densities, which should lead to interesting interactions
when colliding with other objects. White dwarfs and main-sequence stars can
collide at velocities of 10^6 – 10^7 mph, releasing ~ 10^27 times more energy
than an atomic bomb in less than a thousand seconds. Using 3D supercomputer
simulations with detailed physics, we can model a variety of these collisions
and make predictions for the energy that will be released during the event,
as well as the chemical composition and the future evolution of the surviving
star.