ESO’s Very Large Telescope reveals the fingerprints of explosive birth and death of early stars
In an unprecedented breakthrough, researchers utilizing ESO’s Very Large Telescope (VLT) have uncovered the long-sought fingerprints left behind by the explosion of the first stars in the Universe. The team has identified three remote gas clouds whose chemical composition aligns with expectations surrounding these ancient stellar detonations. These findings represent a significant stride towards unraveling the enigma of the initial stars that emerged following the Big Bang.
“By scrutinizing extremely distant gas clouds, we have, for the first time in history, identified the chemical remnants of the explosive deaths of the earliest stars,” declares Andrea Saccardi, a PhD student at the Observatoire de Paris – PSL, who spearheaded this study during his master’s thesis at the University of Florence.
Scientists believe that the first stars, which formed approximately 13.5 billion years ago, were fundamentally distinct from their contemporary counterparts. During their inception, they consisted solely of hydrogen and helium—nature’s simplest chemical elements [1]. These colossal stars, presumed to be tens or even hundreds of times more massive than our Sun, perished rapidly in cataclysmic explosions known as supernovae, enriching the surrounding gas with heavier elements for the first time. Subsequent generations of stars emerged from this enriched medium, in turn dispersing even heavier elements upon their demise. Although the first stars have long vanished, researchers can still glean insights into their nature indirectly by detecting the chemical elements they dispersed throughout their environment after their deaths, explains Stefania Salvadori, Associate Professor at the University of Florence and co-author of the study published in the Astrophysical Journal.
Leveraging data collected by ESO’s VLT in Chile, the team pinpointed three exceedingly remote gas clouds, observable when the Universe was a mere 10-15% of its present age. These clouds exhibited a chemical fingerprint that matched the expected composition resulting from the explosions of the earliest stars. Depending on the mass of these nascent stars and the energy released during their explosions, the initial supernovae unleashed various chemical elements, including carbon, oxygen, and magnesium, which reside in the outer layers of stars. However, some of these explosions lacked sufficient energy to eject heavier elements like iron, which are exclusively found in stellar cores. To detect signs of these first low-energy supernovae, the team focused on identifying distant gas clouds low in iron content but rich in other elements. Remarkably, they discovered precisely that: three distant clouds in the early Universe possessing minimal iron but abundant carbon and other elements—the unmistakable imprint of the very first stars’ explosive finales.
This distinctive chemical composition has also been observed in numerous ancient stars within our own galaxy, which researchers consider to be second-generation stars originating directly from the “ashes” of the initial ones. The current study has now located these ashes in the early Universe, supplying an essential missing piece to this cosmic puzzle. “Our discovery opens up new avenues for indirectly studying the nature of the first stars, complementing our studies of stars within our galaxy,” elucidates Salvadori.
To detect and analyze these distant gas clouds, the team employed luminous beacons known as quasars—brilliant sources powered by supermassive black holes situated at the centers of far-flung galaxies. As quasar light traverses the cosmos, it interacts with gas clouds, imprinting a unique signature on the light that corresponds to the various chemical elements encountered along its path.
To unveil these chemical imprints, the researchers meticulously analyzed data from several quasars observed through the X-shooter instrument on ESO’s VLT. This instrument effectively dissects light into a wide range of wavelengths or colors, providing a unique capability to identify numerous chemical elements within these distant gas clouds.
The groundbreaking findings open up exciting possibilities for future telescopes and instruments, including ESO’s upcoming Extremely Large Telescope (ELT) and its state-of-the-art high-resolution ArmazoNes high Dispersion Echelle Spectrograph (ANDES). With the advanced capabilities of ANDES at the ELT, scientists will have the unprecedented opportunity to study these rare gas clouds in even greater detail, finally shedding light on the mysterious nature of the first stars that ignited the cosmic stage.
Valentina D’Odorico, a researcher at the National Institute of Astrophysics in Italy and co-author of the study, emphasizes the significance of this advancement: “With ANDES at the ELT, we will be able to study many of these rare gas clouds in greater detail, and we will be able to finally uncover the mysterious nature of the first stars.”
The quest to understand the origins of our Universe and the intricate processes that led to the formation of galaxies, stars, and ultimately life itself has taken a significant leap forward. The detection of chemical traces left by the explosions of the first stars offers a tantalizing glimpse into the cosmos’ primordial past. It enables astronomers to piece together the puzzle of our cosmic ancestry and provides crucial insights into the evolution of the Universe over billions of years.
As the exploration of the cosmos continues, the powerful combination of cutting-edge telescopes and innovative techniques promises to unlock even more secrets hidden within the depths of space. The diligent efforts of scientists utilizing ESO’s VLT and the upcoming ELT, along with instruments like ANDES, ensure that humanity’s journey of cosmic discovery will flourish, revealing ever more extraordinary phenomena and unraveling the mysteries of the Universe’s earliest epochs.
In the coming years, astronomers will eagerly await the next wave of revelations as new observations and technological advancements push the boundaries of our understanding. With each breakthrough, we draw closer to comprehending the captivating saga of the first stars and the incredible cosmic dance that shaped the Universe we inhabit today.
Reference: ESO News; https://www.eso.org/public/news/eso2306/
Image Credit: ESO/L. Calçada, M. Kornmesser
