First Molecule After the Big Bang: Astrophysicists Detect Helium Hydride Ion
A research team including scientists from Cologne and Bonn have detected the universe’s first molecule of the in space / publication in ‘Nature’
For the first time, the helium hydride ion HeH+ has been detected in space. Scientists agree that HeH+ was the first molecule to form after the Big Bang. Despite its importance for the history of the early universe, in the past attempts to prove the existence of HeH+ in astrophysical environments had failed. An international research team led by Dr Rolf Güsten from the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn have now succeeded. Scientists from Collaborative Research Centre (CRC) 956 ‘Conditions and Impact of Star Formation’ at the University of Cologne were also involved in detecting the molecule in the planetary nebula NGC 7027. The findings have now been published in ‘Nature’.
‘The chemistry of the universe began with HeH+. The lack of evidence for the existence of this molecule in interstellar space has long been a dilemma for astronomy’, says Rolf Güsten from the MPIfR, first author of the publication and until October 2018 project leader for the GREAT receiver (German Receiver for Astronomy at Terahertz Frequencies). GREAT is a high-resolution spectrometer for astronomical observations on board of SOFIA (Stratospheric Observatory for Infrared Astronomy), a modified Boeing 747 SP aircraft that serves as a flying observatory.
The molecule HeH+ radiates most strongly in a spectral line at a wavelength of 0.149 mm (corresponding to a frequency of 2.01 terahertz). Unfortunately, in this wavelength range the Earth’s atmosphere is completely impermeable to all ground-based observatories. Hence, the search must be carried out either from space or with high-altitude observatories. Due to SOFIA’s flight altitude at approcimately 13 kilometres, the GREAT receiver can operate in this spectral range, explains Professor Dr Jürgen Stutzki of the University of Cologne, who is currently the project leader of GREAT: ‘The astronomical discovery of HeH+ can only succeed in this spectral range. Our receiver for frequencies in the terahertz range impressively demonstrates the scientific potential of this instrument, which we developed and operate together with the MPI for Radio Astronomy within the framework of CRC 956.’