HST Detects Primordial Helium
The Hubble Space Telescope has detected absorption due to single ionized helium (at a rest wavelength of 304 Angstroms) in the UV spectrum of the high-redshift quasar Q0302-003. The quasar has a redshift of 3.286 which places it at roughly 13 billion light years from Earth. This means that the light we now see from the quasar originated from it when the universe was about 10 percent of its present age. The actual helium line was detected at a longer wavelength of 1310 Angstroms due to the Doppler shift.
Both hydrogen and helium are the main products of nucleosynthesis in a Big Bang cosmology. Except for some traces of a few other light elements, all other species are synthesized in stellar nuclear reactions. The detection of helium in the intergalactic medium by HST's Faint Object Spectrograph confirms the standard theory of Big Bang nucleosynthesis. Also, detecting helium in its singly-ionized form agrees with predictions about the physical conditions in the early universe. More observations of other high-redshift quasars will help determine whether or not the helium is actually dispersed between the galaxies or if it is mixed in with hydrogen in discrete clouds.
