In the space between the stars, in the dust from which they are born, scientists have found molecules that had never been seen in space before.
The discovery of revealing emissions in a dense cloud of star formation marks the first time that specific species of a class of molecules known as polycyclic aromatic hydrocarbons have been identified in space, and could finally help unravel the mystery of how and where these molecules form.
“We had always thought that polycyclic aromatic hydrocarbons formed primarily in the atmospheres of dying stars,” said MIT astrochemist Brett McGuire.
“In this study, we found them in cold, dark clouds, where they have not yet begun to form stars.”
Polycyclic aromatic hydrocarbons or PAHs are not exactly rare. Here on Earth, they appear a lot, without waiting for an invitation. They can be found raw: composed of compressed and overheated dead organisms such as zooplankton and algae; and coal: made from compressed and overheated dead plants.
The origins of PAHs can also be non-biological; in fact, as far as we know, most PAHs in the Universe are of abiotic origin. Previous analyzes suggest that about 15 percent of all carbon between stars in galaxies, like ours, is bound to PAH, and most float in space between stars, in the interstellar medium.
Still, all we had was a massive signature indicating to us that there are PAHs, not what individual molecules can be found in interstellar gas.
“Now, for the first time, we have a direct window into its chemistry that will allow us to study in detail how this huge carbon reservoir reacts and evolves through the process of forming stars and planets,” McGuire said.
The focus of the team’s research was the Taurus molecular cloud (TMC-1), which is what it sounds like: a cold, dense molecular cloud in the Taurus sky region, about 430 light-years away.
The team has been traversing this cloud to search for PAH for some time as part of a project called GOTHAM – Green Bank Telescope (GBT) Observations of TMC-1: Hunting Aromatic Molecules.
Molecular clouds are the place where baby stars are born, when a dense knot in the gas collapses under its own gravity as it rotates, enveloping more material about itself from the cloud around it.
However, what the team found inside TMC-1 was not what the models predicted. Obviously, some PAHs were expected, but the abundances were orders of magnitude higher than expected.
Today’s newspaper a Science details the detection of 1- and 2-cyanonaphthalene, but other work in recent months by McGuire and colleagues reveals the sheer richness of what they have discovered through their data stacking techniques: HC4NC, benzonitrile, propargyl cyanide, HC11N, cyanocyclopentadiene, 2-cyanocyclopentadiene, trans-cyanovinylacetylene and vinylcyanacetylene.
“We’ve come across a whole new set of molecules, unlike anything we’ve been able to detect before, and that will completely change our understanding of how these molecules interact with each other. It has branches downstream,” McGuire said.
“When these molecules are large enough to be interstellar dust seeds, they have the potential to affect the composition of asteroids, comets and planets, the surfaces on which ice cream is formed, and perhaps, in turn. , even the places where the planets are located. They form within the stellar systems. “
Currently, the team does not know exactly to what extent 1 and 2-cyanonaphthalene ended up in TMC-1, none of their models could explain the abundance. The two possibilities are that it was formed or transported there; or perhaps a combination of both.
Now that the detection is done, and we know it’s there, scientists can start figuring out that part. We know he is there; we know that somehow he had to get there; figuring out the rest is usually a matter of time.
The discovery also shows that the chemistry of molecular clouds could be much richer and more complex than we thought, and provides us with a new tool for understanding our universe.
“The amazing thing about these observations, this discovery, and these molecules, is that no one had looked at it or looked hard enough,” said astrochemist Michael McCarthy of the Harvard & Smithsonian Center for Astrophysics. “It makes you wonder what’s more we just haven’t looked for.”
The research has been published in Science.