Astronomers have for the first time detected hot cores—warm, molecular-rich cocoons surrounding newborn stars—inside a supernova remnant, a finding that suggests young stars and their complex organic chemistry can survive the violent aftermath of a stellar explosion. The discovery was made using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, and the results were published this month in The Astrophysical Journal.
Hot cores are dense, warm pockets of gas and dust that form around newly born stars. They are known to contain a rich variety of organic molecules, including complex species that are considered potential building blocks for prebiotic chemistry. Until now, such objects had only been observed in relatively quiescent star-forming regions, far from the destructive energy of supernovae.
The research team, led by Takashi Shimonishi of Niigata University in Japan and including scientists from Gifu University, Kyoto University, and the RIKEN research institute, targeted the supernova remnant RX J1713.7−3946. This remnant is the remains of a massive star that exploded approximately 1,600 years ago. The team used ALMA’s exceptional sensitivity and angular resolution to search for signs of newborn stars still embedded in their natal cocoons within this extreme environment.
They succeeded in identifying two distinct hot cores within the remnant. Both objects showed strong molecular emission, revealing a wide array of organic molecules. Remarkably, the relative abundances of complex organic molecules in one of the hot cores were found to be very similar to those seen in ordinary star-forming regions that have not been affected by a nearby supernova.
«These observations indicate that, even in the hostile environment of a supernova remnant, newborn stars can remain well protected inside the cocoons in which they originated, preserving their rich molecular composition,» Shimonishi explained. «Environments capable of hosting complex organic molecules—potential building blocks of prebiotic chemistry—may be more diverse than previously recognized.»
The survival of these hot cores raises intriguing questions about how they withstand the intense radiation and shock waves generated by the supernova. The researchers propose two possible explanations. One is that the hot cores have only recently begun to feel the effects of the supernova, meaning energetic particles have not had enough time to significantly alter their chemistry. Another possibility is that strong magnetic fields, which are thought to be amplified by the supernova shock wave, may hinder the penetration of cosmic rays into the dense molecular gas, effectively shielding the hot cores and preserving their molecular inventory.
While the two hot cores discovered in this study have maintained their molecular richness, it remains unclear whether this is the typical outcome of supernova feedback. Future observations are expected to provide a much more complete picture of the physical and chemical properties of star- and planet-forming regions that have been influenced by supernova explosions.
The findings have implications for understanding the environment in which our own Solar System formed. It is thought that the Solar System may have formed in a region strongly influenced by a nearby supernova explosion. By studying how supernova feedback affects the chemistry of star-forming regions, astronomers hope to learn whether the conditions that gave rise to the Solar System and Earth were typical or exceptional.
The study, titled «Survival of Molecular Complexity under Recent Supernova Feedback: Detection of Hot Cores in RX J1713.7-3946,» was authored by Takashi Shimonishi, Hidetoshi Sano, Kenji Furuya, and Yoko Oya.