Newswise — By utilizing the Very Large Telescope (VLT) of ESO, scientists have identified for the first instance the traces created by the blast of the earliest stars in the cosmos. They observed three remote gas clouds that possess a chemical makeup corresponding to what we anticipate from the initial stellar detonations. Such revelations help us progress towards comprehending the characteristics of the first stars that emerged after the Big Bang.
"Never before have we been able to detect the chemical remnants of the explosions of the earliest stars in such remote gas clouds," stated Andrea Saccardi, a PhD candidate at the Observatoire de Paris - PSL, who headed this research project during his master's degree at the University of Florence."
According to researchers, the earliest stars that emerged in the Universe differed greatly from those we observe today. These stars emerged approximately 13.5 billion years ago, containing solely hydrogen and helium, the most basic chemical elements found in nature [1]. These stars, believed to be tens or hundreds of times more massive than our Sun, perished rapidly in potent explosions, referred to as supernovae, that initially enriched the adjacent gas with heavier elements. Subsequently, later generations of stars were born from the enriched gas, and likewise dispersed heavier elements upon their deaths. However, as the first stars are long gone, researchers must use an indirect approach to learn more about them. "By detecting the chemical elements they disseminated in their surroundings following their demise, we can study primordial stars indirectly," stated Stefania Salvadori, an Associate Professor at the University of Florence and co-author of the research report released today in the Astrophysical Journal.
Utilizing observations acquired with ESO's VLT in Chile, the group identified three extremely distant gas clouds, visible during a time when the Universe was only 10-15% of its present age. These gas clouds exhibited a chemical composition that corresponded to what we anticipate from the explosions of the first stars, depending on their mass and explosion energy. These initial supernovae produced various chemical elements such as carbon, oxygen, and magnesium, which exist in the outer layers of stars. However, some of these explosions did not have enough energy to release heavier elements like iron, which are only present in the cores of stars. To seek out evidence of these first stars, which exploded as low-energy supernovae, the team looked for far-off gas clouds lacking in iron but abundant in other elements. And they discovered just that: three remote clouds in the early Universe with minimal iron but abundant carbon and other elements, the hallmark of the explosions of the very first stars.
This distinct chemical makeup has also been detected in numerous ancient stars in our Milky Way, believed to be second-generation stars that emerged directly from the "remains" of the first stars. This recent research has discovered such remnants in the early Universe, thereby filling a significant gap in our understanding. "Our findings offer novel prospects for exploring the features of the earliest stars, complementing analyses of stars in our galaxy," said Salvadori.
To observe and investigate these far-off gas clouds, the team employed quasars, intense sources of light powered by supermassive black holes located at the centres of distant galaxies. As the light from a quasar journeys through the Universe, it travels through gas clouds where distinct chemical elements leave a signature on the light.
To identify these chemical signatures, the team scrutinized data from multiple quasars that were observed using ESO's VLT with the X-shooter instrument. X-shooter disperses light into an extensive range of wavelengths, or colors, making it a distinctive instrument capable of detecting various chemical elements in these far-off clouds.
This research provides fresh opportunities for the next generation of telescopes and instruments, such as ESO's forthcoming Extremely Large Telescope (ELT) and its high-resolution ArmazoNes high Dispersion Echelle Spectrograph (ANDES). "With ANDES at the ELT, we will be able to explore many of these unusual gas clouds in greater depth, and at last unravel the enigmatic character of the first stars," asserts Valentina D'Odorico, a scientist at the National Institute of Astrophysics in Italy and co-author of the study.
Notes
[1] Minutes after the Big Bang the only elements present in the Universe were the three lightest ones: hydrogen, helium and very small traces of lithium. Heavier elements were formed much later on in stars.
More information
This research was presented in a paper to appear in the Astrophysical Journal (doi: 10.3847/1538-4357/acc39f)
The team is composed of Andrea Saccardi (GEPI, Observatoire de Paris, Université PSL, CNRS, France; Dipartimento di Fisica e Astronomia, University of Florence, Italy [UFlorence]), Stefania Salvadori (UFlorence; INAF – Osservatorio Astrofisico di Arcetri, Italy), Valentina D’Odorico (Scuola Normale Superiore, Italy; INAF – Osservatorio Astrofisico di Trieste, Italy [INAF Trieste]; IFPU – Institute for Fundamental Physics of the Universe, Italy [IFPU]), Guido Cupani (INAF Trieste; IFPU), Michele Fumagalli (Dipartimento di Fisica G. Occhialini, University of Milano Bicocca, Italy; INAF Trieste), Trystyn A. M. Berg (Dipartimento di Fisica G. Occhialini, University of Milano Bicocca, Italy), George D. Becker (Department of Physics & Astronomy, University of California, USA), Sara Ellison (Department of Physics & Astronomy, University of Victoria, Canada), Sebastian Lopez (Departamento de Astronomía, Universidad de Chile, Chile).
The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration in astronomy. Established as an intergovernmental organisation in 1962, today ESO is supported by 16 Member States (Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom), along with the host state of Chile and with Australia as a Strategic Partner. ESO’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvellous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its Very Large Telescope Interferometer, as well as survey telescopes such as VISTA. Also at Paranal ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. Together with international partners, ESO operates ALMA on Chajnantor, a facility that observes the skies in the millimetre and submillimetre range. At Cerro Armazones, near Paranal, we are building “the world’s biggest eye on the sky” — ESO’s Extremely Large Telescope. From our offices in Santiago, Chile we support our operations in the country and engage with Chilean partners and society.
Links
- Research paper
- Photos of the VLT
- For journalists: subscribe to receive our releases under embargo in your language
- For scientists: got a story? Pitch your research
RSS