A peculiar meteorite discovered in western Egypt in 1996 could contain microscopic particles of supernova debris, and not just any supernova, but one caused by the explosion of a white dwarf, the residual core of a previously Sun-like star. If that's the case, it'll be the first proof of a close supernova that occurred before the Sun and planets were born.
Hypatia is the name of the stone, and it was immediately recognised as an outlier. It was first disputed whether it was a meteorite at all, but laboratory examinations revealed that the structure and elemental makeup were similar enough to one type of meteorite that it appeared to be extraterrestrial in origin.
Carbonaceous chondrite is the name given to this type of meteorite. These have a lot of carbon in them, and many of them have chondrules, which are tiny, roundish grains of material that originated early in the process that created the Sun, planets, asteroids, and everything else in our solar system.
One type, known as the CI group, has extremely few chondrules or none at all, and Hypatia appears to be one of them. This meteorite group is exceedingly old, implying that it formed before the Sun and planets consolidated from a cloud of gas and dust known as the solar nebula. Hypatia, in reality, originated less than 40 million years after the solar nebula began to collapse, based on the abundance of a xenon isotope.
Hypatia is difficult to examine because only a little fragment weighing 30 grams (a little over an ounce) was discovered. Despite this, research have revealed that it contains two separate types of bulk material. One appears to have no heavier elements than oxygen, but the other contains significant amounts of heavier elements such as iron and nickel.
Those elements are fascinating: they are created when stars burst and become supernovae. The blast is so intense that the expelled material undergoes thermonuclear fusion, resulting in the formation of heavy elements.
The relative abundances of these components, on the other hand, are crucial. The amount of silicon present in comparison to iron, for example, can reveal more information about the material's origin. Scientists discovered that these grains in Hypatia were exceedingly low in silicon and manganese when compared to iron in the latest study, which is quite unusual.
The scientists were able to rule out the type that results from the core collapse of a large star at the conclusion of its life by examining elemental production processes in different types of supernovae; this does not produce elements in the appropriate quantities to match Hypatia.
When a very dense white dwarf — the compressed core of a star like the Sun left over after the star evolves into a red giant and blows away its outer layers, exposing the core to space — gathers material from a binary companion star, it is known as a Type Ia supernova. It can accumulate so much material that the white dwarf's high gravity initiates fusion, releasing so much energy that the star rips itself apart and explodes. This type of supernova has several subclasses, including one in which the white dwarf gathers a helium shell from the other star, which, when fused, triggers the considerably more intense fusing of carbon inside the dwarf.
This is not a very frequent type of supernova — albeit the very first extragalactic supernova ever witnessed, SN 1885A in the Andromeda galaxy, was of this type* — but they do produce a distinctive elemental abundance, which models suggest matches Hypatia's well enough to be suspicious.
Hypatia's high carbon content could have a similar genesis. The star is a red giant before it becomes a white dwarf, and red giants can have a lot of carbon in them that blasts away into space, generating sooty grains of material known as dust. It's possible that the explosion happened within a cloud of this material, which then clumped together. This debris eventually made its way to the nebula that gave birth to the solar system. That's not unusual; we know that some of the carbon in meteorites came from other stars that also polluted the solar nebula.
But none of this is — excuse the term — fixed in stone. Hypatia is small and difficult to analyse in traditional methods, and some of the conclusions reached contradict conventional wisdom. For example, current understanding is that much of the material in the solar nebula was thoroughly mixed, whereas the material inside Hypatia is not. That isn't a deal-breaker, but it does suggest that this new study goes against the grain.
If this theory proves to be correct, it will be the first direct evidence of a nearby white dwarf supernova that occurred before our planet was born. It's possible that it wasn't the only supernova or source of interstellar material that fed our birth nebula, but pinpointing it would disclose a lot about what transpired in space to create our solar system.
Keep in mind that the material in this pre-solar nebula was used to create everything you see around you, including the atoms inside you. You are, as Carl Sagan put it, "star material."
And you're exploding star material. This is supernova stuff. It's an incredible notion, made even more incredible by the fact that it's clearly accurate.
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