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Astronomers detect the Universe’s “first molecular bond”

Credit: NGC 7027 nebula Credits: Hubble / NASA / ESA / Judy Schmidt)

Helium hydride ion (HeH+ ), believed to be the Universe’s “very first molecular bond” created after the Big Bang, has been detected in Space for the first time.  Astronomer’s spotted this molecule about 3,000 light years from Earth. 

After decades of research, Helium hydride ion (HeH+), a compound composed of helium and hydrogen atoms, has just been spotted in the planetary nebula of NGC 7027, situated about 3,000 light years from Earth.  Researchers were able to detect this compound by installing a telescope on board the SOFIA plane, NASA’s Stratospheric Observatory for Infrared Astronomy.  This conclusive discovery confirms theoretical predictions about essential chemistry.

The lack of evidence of the very existence of helium hydride in the local Universe has called into question our understanding of the chemistry in the early Universe,” explains astronomer Rolf Güsten, the main author of the work published in the Nature journal.  “The reported discovery now resolves previous doubts.”.

First molecular connection

Helium hydride could, in some senses, mark the beginning of chemistry.  While the rest of the Big Bang was in the process of cooling down to about 4,000 Kelvins and ions were starting to connect with electrons to form neutral atoms, it is believed that neutral helium was reacting with hydrogen ions to form the first chemical bond, creating the very first molecule.

As early as 1925 chemists managed to recreate helium hydride ion in laboratories.  However only in 1970 did astronomers start to discuss the possibility of this molecule being detected in Space today.  Researchers have therefore been looking into planetary nebulae.  These expanding ionised gas clouds emitted during the last stages of a star’s life represent a similar state to the aftermath of the Big Bang, chemically speaking.

nébuleuse
La NGC-7027 nebula. Credits : Scientific center SIRTF/Caltech – NASA/ESA

Taken from above

For the last forty years, astronomers have tried to identify this molecular bond “in its natural state“.  However their efforts have been in vain.  Earth’s atmosphere, which hampers the view of land based spectrometers, is the main reason for their lack of clarity.

Researchers turned towards the capabilities of the German receptor GREAT to try and overcome this problem.  Simply speaking, this device is able to produce a high resolution spectrum in several frequency windows.  Astronomers eventually got what they were looking for after installing this machine onto NASA’s high altitude SOFIA plane. The device detected the first unambiguous signal of the Universe’s “first molecular bond”.

Previous theories that this molecular ion can be effectively created in Space have now been confirmed by this detection. It could be said that thanks to this “chemical base“, the Universe has been able evolve as it has for the last 13 billion years.

The study into the Astrophysical detection of the helium hydride ion HeH+ can be found in the Nature journal published 17 April 2019.

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