May 9 2022Reviewed by Alex Smith
Researchers at the RIKEN Cluster for Pioneering Research utilized computer modeling to explain how a hypothesized form of supernova would develop over thousands of years, providing researchers with a means to look for examples of “D6” supernovae.
Image Credit: Shutterstock.com/muratart
Supernovae are essential in cosmology because one type, Ia, is used as a “standard candle” that permits distance to be determined, and they were used for the observations that revealed, to the surprise of many observers, that the universe is accelerating.
Although it is widely assumed that type Ia supernovae are formed by the explosion of degenerate stars known as white dwarfs — stars that have burned through their hydrogen and contracted into compact objects — the process behind the explosions is unknown.
The recent discovery of extremely fast-moving white dwarfs has provided credence to one suggested process for the creation of these supernovae, D6. In this case, one of two white dwarfs in a binary system experiences a “double detonation,” in which a helium surface layer bursts first, followed by a greater explosion in the star’s carbon-oxygen core.
This causes the star to explode, and the companion, instantly free of the bursting star’s gravitational pull, is thrown out at incredible speeds.
However, nothing is known about the aftermath of such an event long after the first explosion. The researchers chose to investigate this by simulating the long-term evolution of a supernova remnant over thousands of years after the blast.
They were able to see some features in the progenitor system that were unique to this circumstance, providing a way to investigate supernova physics, such as a “shadow” or dark patch encircled by a luminous ring. They also discovered that, contrary to popular belief, the leftovers of type Ia explosions are not always symmetric.
The D6 supernova explosion has a specific shape. We were not confident that it would be visible in the remnant long after the initial event, but we found that there is a specific signature that we can still see thousands of years after the explosion.
Gilles Ferrand, Study First Author, RIKEN Cluster for Pioneering Research
According to Shigehiro Nagataki, the leader of RIKEN’s Astrophysical Big Bang Laboratory, “This is a very important finding because it could have an impact on the use of Ia supernovae as cosmic yardsticks. They were once believed to originate from a single phenomenon, but if they are diverse, then it might require a reevaluation of how we use them.”
Moving forward, we plan to learn how to more precisely compute the X-ray emission, taking into account the composition and state of the shocked plasma, to make direct comparisons with observations. We hope that our paper will give new ideas to observers, of what to look for in supernova remnants.
Gilles Ferrand, Study First Author, RIKEN Cluster for Pioneering Research
The study was done in unification by an international group including scientists from the University of Manitoba.
Journal Reference:
Ferrand, G., et al. (2022) The Double Detonation of a Double-degenerate System, from Type Ia Supernova Explosion to its Supernova Remnant. The Astrophysical Journal. doi.org/10.3847/1538-4357/ac5c58.
Source: https://www.riken.jp/en/