Astronomy at FAU: Stellar evolution in the neighborhood
Researchers at FAU have discovered two as yet unknown supernova remnants in our neighboring galaxy.
The Large Magellanic Cloud (LMC) is a satellite galaxy of the Milky Way and is located around 160,000 light years away from our solar system. This relative proximity makes it an ideal laboratory for studying cosmic explosions and stellar evolutionary processes. Supernovae as the exploding final stages of stars play an important role here. They catapult large amounts of matter in something known as supernova remnants (SNR) into interstellar space, from which new stars and planets are then formed.
The outer peripheries of the LMC have not yet been well researched up to now. Based on previous investigations, astrophysicist Manami Sasaki and her doctoral candidate Federico Zangrandi suspected that stellar explosions also occur there. For the first time, they have now identified and confirmed two SNR in far-off outer regions with the aid of modern detection instruments. “We were surprised to discover that these two light sources were the remnants of supernovae – a long distance away from other echoes of stellar explosions that we were already familiar with,” says Prof. Manami Sasaki, who leads the Multiwave Astronomy Group at the Remeis Observatory at the Astronomical Institute of FAU. The researchers suspect that both stars were probably ripped out of the center of the LMC due to interactions between it, its companion, the Small Magellanic Cloud, and the Milky Way.
A look into the cosmos
“This shows that supernova explosions also occur on the peripheral regions of the Large Magellanic Cloud. The dying star was in an environment that was dense enough with ionized gas, i.e. charged particles, for the shock of a supernova to leave such an imprint on the surroundings. This is not the type of gas that we have previously found in the outer reaches of galaxies,” explains Sasaki.
The researchers were able to make their discoveries thanks to the XMM Newton observatory of the ESA, which is investigating energy-rich processes in the X-ray range, and the eROSITA X-ray telescope. They estimate that both stars exploded around 20,000 years ago. This date is based on the analysis of the size and structure of the remnants as well as on models of the expansion of supernova explosions.
The analyses of the SNR also provided information about the chemical composition of the emitted matter. Of particular interest is the abundance of heavy elements such as iron and oxygen, which are produced by nuclear fusion inside stars and in supernova explosions. “Such elements are crucial for the chemical evolution of the universe and influence the formation of new celestial bodies. Our solar system was also created in this way,” says Sasaki.
Understanding how stars develop
Investigating supernova remnants not only improves our understanding of how galaxies develop. With these newly-discovered remnants, the researchers have now proved that the outer peripheries of the LMC were the location for huge stellar explosions. Their findings will help us to better understand the history of this satellite galaxy and its interactions with the Milky Way. The international research community can also refine its models on the development of supernovae on the basis of these findings.
In addition, the differences between supernova remnants in the LMC and in the Milky Way could provide useful information about star formation processes in various galactic environments. This could one day enable us to clarify how elements that are vital to life on Earth were distributed across the universe. “With each new discovery, we can provide more accurate answers to one of the biggest questions in astronomy: How did the universe develop and which role does our own galaxy play in this development?,” says Manami Sasaki.
The ESA has published images of two supernova remnants on its website:
‘Letter to the Editor’ in the journal Astronomy & Astrophysics:
Further information:
Prof. Dr. Manami Sasaki
Dr. Karl Remeis observatory
Tel. +49-951-95222-19
manami.sasaki@fau.de