January 22, 2014
An international team, with the participation of the Center for Astrobiology (CSIC-INTA), observing the Crab Nebula in the infrared with the HERSCHEL space observatory has found the first evidence of a molecule based on the noble gas argon in space
One of the bases on which Astrophysics is based to interpret what is observed in the Universe is to consider that the laws of Physics and Chemistry are the same in their entirety and, therefore, all the elements that we know on Earth they are the same that we could find in any other galaxy. Also, saving the conditions of each place, the atoms and molecules must be the same. However, until now, there was a class of molecules that had not been found: the one that is made up of the so-called noble gases.
Using the traditional representation of the Periodic Table of the Elements, arranged according to their atomic number and aligned by the number of “outer” electrons (those that give them their chemical characteristics), in the rightmost column are the noble gases: helium, neon, argon, krypton, xenon, and radon. As they have a complete external level of electrons (two in the case of helium and eight for the rest), they are normally found in nature in isolation since their ability to react with other elements and form compounds is very low. But not null and in the laboratory a good number of molecules formed by noble gases have been studied.
Although space seems to be a good chemical laboratory in which a varied series of compounds are produced, from the simplest and most abundant molecules such as water (H2O) or carbon dioxide (CO2), to large organic molecules such as PAH or some amino acids, in the case of noble gases things are not so simple. Thus, although noble gas atoms or ions had already been detected, until now none of the noble gas-based compounds had been found, suggesting that these elements require a longer reaction time with other species in space.
A new study led by Michael Barlow from University College London (United Kingdom), in which José Cernicharo, CSIC Research Professor at the Center for Astrobiology (CAB, CSIC-INTA) participates, and based on data obtained with the Space Observatory ESA’s Herschel has found the first evidence of one of these components in space by detecting the emission of argon hydrile (ArH +), a molecular ion that contains the noble gas argon, in the Crab Nebula. The results are published in the prestigious journal Science.
“These types of molecules had been produced in laboratories but it was not known whether adequate conditions existed in space for their formation. Now we know that it is and this discovery will allow us to study much more in detail the interaction of supernovae with the environment that surrounds them ”, highlights José Cernicharo, CSIC Research Professor at the Center for Astrobiology (CSIC-INTA). The compound found is based on the isotope (isotopes are elements with the same number of protons in their nucleus but that differ in the number of neutrons) of argon with atomic mass 36 (36Ar) as opposed to 40Ar which is the one found usually on Earth. This is because 40Ar on Earth comes from the decay of potassium, while 36Ar, which is the most abundant in space, is produced abundantly in supernova explosions.
The Crab Nebula (Messier 1) is a fuzzy, filamentous structure in the constellation Taurus formed after a supernova explosion observed in 1054 by Chinese astronomers.
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