Supernovae are so powerful they create new atomic nuclei. As a massive star collapses, it produces a shockwave that can induce fusion in the star’s outer shell. These fusion reactions create new atomic nuclei in a process called nucleosynthesis. Supernovae are considered one of the original sources of the elements heavier than iron in the Universe.

In addition to making elements, supernovae scatter them. The elements that are made both inside the star as well as the ones created in the intense heat of the supernova explosion are spread out into the interstellar medium. These are the elements that make up stars, planets and everything on Earth -- including ourselves. ... Though these explosions only occur a few times a century in our Galaxy, they are responsible for the synthesis of all the elements heavier than iron, including many we come across in daily life, like copper, mercury, gold, iodine and lead. ... The supernova has thus enriched the interstellar medium with heavy elements across a sphere a thousand light years across or so.

These ground-breaking explorations made clear that isotopes and elements heavier than iron can only be made by neutron capture due to the rising electrostatic repulsion with increasing nuclear charge. Solar abundances indicated that two different neutron-capture processes dominate, either the slow-neutron-capture process, i.e. the s-process, or the rapid-neutron-capture process (r-process)… As mentioned above, it has been known since and that the majority of all isotopes and elements heavier than iron are synthesized either by the s-process or the r-processes in roughly equal amounts… Based on investigations related to high entropy ejecta from core-collapse supernovae… the idea emerged that in the case of high entropies only slightly neutron-rich matter could lead to an r-process.

The production of about half of the heavy elements found in nature is assigned to a specific astrophysical nucleosynthesis process: the rapid neutron-capture process (r process)… (b) While for many years the occurrence of the r process has been associated with supernovae, where the innermost ejecta close to the central neutron star were supposed to be neutron rich, more recent studies have cast substantial doubts on this environment. Possibly only a weak r process, with no or negligible production of the third r-process peak, can be accounted for, while much more neutron-rich conditions… are likely responsible for the majority of the heavy r-process elements. Such conditions could result during the ejection of initially highly neutron-rich matter, as found in neutron stars… Possible scenarios are the mergers of neutron stars… but also include rare classes of supernovae as well as hypernovae or collapsars with polar jet ejecta.

Supernovae are the source of most of the heavy elements in the Universe. Elements heavier than iron cannot be produced by normal nuclear fusion in stars, and are instead created during supernova explosions by rapid neutron capture (the r-process). The explosion then ejects these newly formed heavy elements into space, where they mix with the interstellar medium and become part of subsequent generations of stars and planets.

The sequence of stellar burning is terminated when the core of the star is largely composed of elements in the mass region of nickel and iron, because no more energy is to be gained from further nuclear reactions. As it has been seen in the preceding sections, stellar burning phases only lead to the production of nuclei up to Fe. Due to the lack of a Coulomb barrier, the most likely process for the formation of elements heavier than those grouped around iron is neutron capture. If a supply of neutrons is available, they can accrete by sequential neutron captures on a "seed nucleus" in the region of iron to build up neutron-richer nuclei.

When the Universe came into existence ~14 billion years ago, the only elements were hydrogen, helium, and traces of lithium, beryllium, and boron. The heavier elements did not yet exist. Heavy elements are produced by nucleosynthesis – the fusion of nuclei deep within the cores of stars. At some point in time, the first stars were formed, and within their cores the fusion process created heavier and heavier elements; the most massive stars produced nuclei as heavy as iron. More massive stars explode as supernovae, leaving neutron stars or black holes at the centers of the supernova remnants. The elements that were created within the cores of the first stars were ejected into space where they intermingled with the surrounding interstellar medium.

This astrophysical review states: "In massive stars, fusion proceeds until an iron core forms, after which further fusion is endothermic. The subsequent core‑collapse and supernova explosion eject the overlying shells, enriched in elements up to and including the iron peak." It adds that neutron‑capture processes in these explosions "are responsible for producing many of the elements heavier than iron, which are then mixed into the interstellar medium by the supernova ejecta."

In an educational caption about a supernova remnant, NASA notes: "Supernovae are the universe's way of creating and dispersing many of the elements heavier than hydrogen and helium." It explains that when the star explodes, "the blast wave and ejecta scatter newly synthesized elements, including those heavier than iron, into the surrounding space, where they will help form new stars, planets, and even life."

The rapid neutron capture process (r-process) is responsible for the production of approximately half of the elements heavier than iron. For a long time, core-collapse supernovae were considered as the most promising site. However, more recent studies have shown that neutrino-driven winds from proto-neutron stars in core-collapse supernovae may not always reach the necessary conditions for a robust r-process. Compact binary mergers involving neutron stars have emerged as an additional, and possibly dominant, site of r-process nucleosynthesis, although contributions from various types of supernovae and other explosive events are still expected.

The electromagnetic counterpart of GW170817, in particular the ultraviolet, optical and infrared emission, is consistent with expectations for a 'kilonova' powered by the radioactive decay of r-process nuclei synthesized in the ejecta. The inferred ejecta masses and velocities imply that neutron-star mergers can produce substantial amounts of r-process elements, including those heavier than iron, and thus contribute significantly to the chemical enrichment of the Universe.

Star dissolution via high-energy photon jet offers an alternative origin for the production of heavy elements and the kilonova they may manufacture, a possibility not previously thought to be associated with collapsing stars. As proposed in The Astrophysical Journal, high-energy photons produced deep in the jet could dissolve the outer layers of a star into neutrons, causing a series of physical processes that results in the formation of heavy elements. "There are only a few viable yet rare scenarios in the cosmos where these elements can form, and all such locations need a copious amount of neutrons. We propose a new phenomenon where those neutrons don’t pre-exist but are produced dynamically in the star."

Astronomers have for the first time directly observed the aftermath of a collision between two neutron stars, an event called a kilonova. The gravitational-wave event GW170817 and its electromagnetic counterparts showed that such mergers are prolific sites of rapid neutron-capture (r-process) nucleosynthesis. The spectra of the kilonova indicate the presence of newly synthesized heavy elements, including lanthanides, demonstrating that neutron star mergers are a major source of elements heavier than iron in the Universe.

The astrophysical site (or sites) of the rapid neutron capture process (r-process) has been a mystery for decades. The discovery of r-process enrichment in ultra-faint dwarf galaxies and the observation of the neutron star merger GW170817 support the idea that neutron star mergers are a dominant source of r-process elements. However, some models of core-collapse supernovae, particularly those with strong magnetic fields and rapid rotation (magnetorotational supernovae), can also produce significant r-process material. The relative contributions of neutron star mergers and supernovae to the Galactic inventory of elements heavier than iron remain an open question.

The heaviest elements made this way are iron and nickel; heavier elements are thought to be built by slow and/or rapid neutron-capture reactions, the s- and r-processes… During the later stages of the explosion the matter is expected to become rich in neutrons, so supernovae are believed to be the site of heavy-element production by the r-process… This heavy-element production can be attributed to a novel nucleosynthesis process, which Fröhlich and colleagues named the νp process… The νp process is a primary process, that is, it should occur in all core-collapse supernovae.

The accompanying teacher materials summarize: "Most elements heavier than iron are formed during violent cosmic events such as supernova explosions and neutron star collisions." It further explains that these explosions "spew the newly formed heavy elements into space, where they mix with existing gas and dust and eventually become part of new stars and planetary systems."

Instead, most of the metals we observe in the Universe have been produced and scattered by the titanic explosions that mark the end for many stars – supernova explosions. Modern research has shown that different elements are produced by the different types of supernova. A Type II supernova (the explosion of a massive star) will produce mainly light metals such as carbon and oxygen. In contrast, a Type Ia supernova (the explosion of a white dwarf star in a binary system) will produce mainly heavy metals such as iron and nickel.

Studies of the chemical composition of old stars in the Milky Way halo have shown that some of them are strongly enriched in elements heavier than iron that can only be formed in neutron-capture processes. The abundance patterns in so-called r-process enhanced stars indicate that a small number of rare, prolific events—such as neutron star mergers or certain types of core-collapse supernovae—have contributed substantially to the inventory of heavy elements in the Galaxy, whose products were then dispersed into space and later incorporated into subsequent generations of stars.

This article addresses three of the four nucleosynthesis processes involved in producing heavy nuclei beyond Fe (with a main focus on the r-process)… Opposite to the fourth process (the s-process), which operates in stellar evolution during He- and C-burning, they are all related to explosive burning phases, (presumably) linked to core collapse supernova events of massive stars… Several studies… presented arguments supporting constant relative ratios of r-process element abundances… This suggests that a unique r-process exists in nature, at least for heavy elements… The lighter r-process and possibly p-process elements, including also νp-process nuclei, might have a different (and more frequent) origin than the main/heavy (apparently unique) r-process component.

“Free neutrons are unusual because they are so short-lived. But large numbers of neutrons are liberated at some events in the universe. One example is when a massive star dies, exploding into a supernova,” explains Andreas Heinz. ... Observations and calculations have indeed shown that flows of neutrons in supernovae give rise to many heavier elements. But as long ago as the 1950s scientists realized that supernovae alone hardly suffice to explain the existence of some heavy elements – among others gold and platinum. ... The observations gave strong indications that heavy elements are formed in neutron star collisions.

Magnetar flares, colossal cosmic explosions, may be directly responsible for the creation and distribution of heavy elements across the universe, suggests a new study. Researchers estimate that up to 10% of these heavy elements in the Milky Way are derived from the ejections of highly magnetized neutron stars, called magnetars.

Supernovae are among the most spectacular and energetic events in the universe, causing the explosive death of massive stars and significantly influencing the evolution of galaxies. These stellar explosions not only release enormous amounts of energy but also play an important role in the synthesis and dispersal of heavy elements. These explosions primarily synthesize elements like carbon, oxygen and heavier elements up to iron through nucleosynthesis processes, which then get expelled into the Interstellar Medium (ISM). Type II supernovae are responsible for synthesizing a broad range of heavy elements, including those beyond iron, through a process called neutron capture.

This shock wave compresses the material it passes through and is the only place where many elements such as zinc, silver, tin, gold, mercury, lead and uranium are made. Massive stars also have an onion-like structure with iron fused in the center, showing that heavier elements are created in the star and dispersed by the explosion.

About half of the chemical elements heavier than iron that are found in nature are produced during the rapid neutron-capture process (r process)… In August 2017, the observation of the kilonova light curve… produced by the radioactive decay of r-process nuclei synthesized during the merger of two neutron stars, marked the beginning of a new era for r-process studies where nucleosynthesis predictions can be directly confronted with astronomical observations.

The first stars in the universe were comprised of hydrogen, helium, and a trace amount of lithium. The largest of these stars fused hydrogen and helium into heavier elements and scattered these elements into interstellar space when they reached the supernova phase. A second generation of stars formed from the ashes of the first. The largest of these second-generation stars more efficiently generated heavy elements and, when they went supernova, scattered far more heavy-element-enriched ashes into interstellar space. Third-generation stars, like our Sun, formed from the ashes of second-generation stars.

In stellar nucleosynthesis, fusion in normal stellar cores stops at iron, because fusing iron does not release energy. Elements heavier than iron are mainly formed in explosive or neutron-capture environments, and supernovae help disperse these newly made elements into the interstellar medium.

Around timestamp 576 s, the narrator states: "So yes today we have proof that it is indeed the neutron star merger which is the dominant site for creation of these heavier than iron elements, not supernova, neutron star mergers." Later, around 1132 s, they summarize: "All the elements that are heavier than iron… 50% of them are created by the r process in neutron star mergers and some of them in supernovae as well and the remaining 50% of them are created" in certain dying stars via the s-process. The video thus presents the modern view that while supernovae contribute, they may not be the dominant source of elements heavier than iron.

The explanation given is: "Elements heavier than iron are formed in a star through the process of supernova nucleosynthesis." It continues: "When a star runs out of fuel, it undergoes a catastrophic explosion known as a supernova... allowing for the fusion of heavier elements." The newly formed elements are then "scattered into space, where they can eventually become part of a new star and its planets."