Webb Telescope Discovers Tellurium, a Rare Cosmic Element from Star Merger
Oct 25, 2023 - In a groundbreaking discovery, NASA's James Webb Space Telescope has unveiled the cosmic origins of rare heavy elements, providing a deeper understanding of our universe. This monumental revelation, resulting from the observation of an exceptionally bright gamma-ray burst, GRB 230307A, has been achieved through an unprecedented collaboration of space and ground-based telescopes. Let's embark on a cosmic journey to explore how Webb's role in this discovery is revolutionizing our comprehension of celestial events.
Unveiling the Cosmic Drama: In a cosmic drama that unfolded over the span of several hundred million years, Webb, alongside NASA's Fermi Gamma-ray Space Telescope and NASA's Neil Gehrels Swift Observatory, made an extraordinary discovery. These telescopes collectively observed GRB 230307A, one of the brightest gamma-ray bursts ever recorded, and identified the neutron star merger that triggered this spectacular event. This unique phenomenon is termed a kilonova, a cosmic explosion caused by the merger of either neutron stars or a neutron star and a black hole.
The Discovery of Tellurium: Webb's involvement in this discovery was pivotal. It helped scientists detect the presence of the chemical element tellurium in the aftermath of the kilonova. Tellurium, a rare and heavy element on Earth, holds the key to unraveling the cosmic processes responsible for creating such elements. Interestingly, other elements located near tellurium on the periodic table, including iodine, essential for life on our planet, are also believed to be present among the material ejected by the kilonova.
Andrew Levan of Radboud University and the University of Warwick, lead author of the study, expressed the significance of this discovery. He stated, "Just over 150 years since Dmitri Mendeleev wrote down the periodic table of elements, we are now finally in the position to start filling in those last blanks of understanding where everything was made, thanks to Webb."
Unraveling the Mystery of Neutron Star Mergers: Neutron star mergers have long been theorized as celestial "pressure cookers" capable of generating heavy elements far heavier than iron. However, obtaining concrete evidence of this phenomenon has presented astronomers with significant challenges. Kilonovae, the explosions resulting from these rare mergers, are exceptionally infrequent, making them elusive subjects of study.
In the case of GRB 230307A, the discovery is especially remarkable. Detected by the Fermi telescope in March, it marked the second brightest gamma-ray burst in over half a century of astronomical observations. It was approximately 1,000 times brighter than typical gamma-ray bursts observed by Fermi and endured for a remarkable 200 seconds, categorizing it as a long-duration gamma-ray burst.
Eric Burns, a co-author of the study from the Fermi team at Louisiana State University, emphasized that this burst, despite its brightness and duration, originated from a merging neutron star, redefining our understanding of long-duration gamma-ray bursts.
The Power of Telescope Collaboration: The strength of this discovery lies in the collaboration of multiple telescopes, both ground-based and in space. Together, they pieced together a treasure trove of information from the moment the burst was first detected, underscoring the synergy of satellites and telescopes working together to witness the ever-changing universe.
Following the initial detection, a series of intensive observations from ground and space-based instruments, including Swift, swung into action to pinpoint the burst's source and track changes in its brightness. These observations, spanning across the gamma-ray, X-ray, optical, infrared, and radio spectra, confirmed the unique characteristics of a kilonova.
Om Sharan Salafia, a co-author of the study from the INAF – Brera Astronomical Observatory in Italy, explained that kilonovae are rapid explosions, and as the ejected material expands, it cools quickly, causing its peak light emission to shift towards the infrared and become increasingly red over days to weeks.
Webb's Role in the Revelation: During the observation of this kilonova, Webb's Near-Infrared Camera (NIRCam) and Near-Infrared Spectrograph (NIRSpec) played a pivotal role. These highly sensitive instruments, designed to peer deep into the cosmos, were uniquely suited to observe this tumultuous cosmic event. The resulting spectrum revealed broad lines indicative of material ejected at high speeds. More importantly, it showcased the unmistakable presence of tellurium, an element rarer on Earth than platinum.
The utilization of Webb's infrared capabilities allowed scientists to determine the precise location of the two neutron stars that were responsible for the kilonova. They were found in a spiral galaxy situated roughly 120,000 light-years away from the merger site.
These neutron stars, once part of a binary system in their home spiral galaxy, embarked on an incredible cosmic journey. Despite both stars undergoing explosive supernova events, they remained gravitationally bound. Their journey saw them propelled out of their home galaxy, traveling a distance equivalent to the diameter of the Milky Way galaxy, before merging several hundred million years later.
Future Prospects: The collaboration and discoveries made in this extraordinary event signal the promise of even more revelations in the future. The increasing integration of space and ground-based telescopes will offer astronomers enhanced opportunities to explore changes in the universe. For instance, while Webb is capable of peering deeper into space than ever before, the forthcoming Nancy Grace Roman Space Telescope is expected to provide a remarkable field of view. This will empower astronomers to not only identify where these cosmic explosions occur but also to study their frequency and characteristics in greater detail.
Ben Gompertz, a co-author of the study from the University of Birmingham in the UK, expressed optimism regarding Webb's future contributions. With more frequent observations, evolving models, and an enhanced understanding of spectra over time, Webb is poised to revolutionize our comprehension of the universe.
The discovery facilitated by NASA's James Webb Space Telescope represents a transformative moment in our quest to understand the cosmos. The identification of tellurium in the aftermath of a neutron star merger marks a significant leap in our comprehension of the universe's elemental origins. As we explore deeper into the cosmos, the mysteries of the universe are gradually unfolding, revealing our place within it. The future holds even more exciting prospects, promising to unlock the universe's deepest secrets, one discovery at a time. Webb's role in this monumental revelation reaffirms its status as the world's premier space science observatory, shedding light on the enigmatic structures and origins of our universe. This groundbreaking research, published in the journal Nature, will undoubtedly inspire future explorations and investigations into the mysteries of space.
Source - NASA
This graphical representation illustrates the comparison between the spectral data of the kilonova associated with GRB 230307A, as observed by the James Webb Space Telescope, and a kilonova model. Both spectra reveal a prominent peak within the tellurium-associated region, highlighted in red. The detection of tellurium, an element scarcer on Earth than platinum, signifies Webb's inaugural direct observation of a heavy element within a kilonova.Neutron star mergers have long been proposed as the ideal crucible for the creation of chemical elements, including those vital for life. However, these rare and fleeting phenomena, known as kilonovas, have proven elusive. Webb's Near-Infrared Spectrograph (NIRSpec) successfully captured the spectrum of GRB 230307A's kilonova, supplying compelling evidence of heavy element synthesis stemming from neutron star mergers. With Webb's extraordinary capacity to peer deeper into the cosmos, astronomers anticipate the discovery of more kilonovas, promising further insights into the formation of heavy elements. Image Credits: Illustration by NASA, ESA, CSA, Joseph Olmsted (STScI)