Recent research into the kilonova AT2017gfo has provided groundbreaking insights into the formation of atomic elements following neutron star collisions. Published in the journal Astronomy and Astrophysics, the study led by Albert Sneppen from the Cosmic Dawn Center and the Niels Bohr Institute highlights the unique opportunity to observe the synthesis of heavy elements during this energetic event.
Kilonovae, resulting from the merger of neutron stars, release immense energy and create a plasma ball that expands outward. As this plasma cools, nucleosynthesis occurs, producing elements such as gold, platinum, and uranium through the rapid neutron capture process (r-process). This study marks the first instance where astronomers have observed the formation of atoms in a kilonova, providing a clearer understanding of the conditions similar to those present shortly after the Big Bang.
The research utilized multiple ground-based telescopes and the Hubble Space Telescope to capture spectra from 0.5 to 9.4 days post-merger. Observations focused on optical and near-infrared wavelengths, which allowed researchers to analyze the rich spectra of newly formed elements, including strontium, tellurium, lanthanum, cesium, and yttrium.
Notably, the P Cygni spectral line played a crucial role in this research, revealing the dynamics of the expanding gas shell around the kilonova. The complexity of the spectra provided insights into the velocity, density, temperature, and ionization of the ejecta.
The kilonova produced approximately 16,000 Earth masses of heavy elements, with around 10 Earth masses attributed to gold and platinum. Additionally, the event is linked to the gravitational wave detection GW170817, marking the first observation of a gravitational wave event alongside its electromagnetic counterpart.
This research enhances our understanding of kilonovae as mini-laboratories for extreme nuclear physics and their role as significant contributors to the synthesis of heavy elements in the universe.