Victoria astronomer hits the gas on a stellar problem
New research from Victoria astronomer Dr Stephen Curran aims to understand a 13 billion year old mystery about how the formation of stars is fuelled.
20 September 2017
Dr Curran says, “stars are still being born at a rate of one every 100 years per cubic light-year of space. However, at its peak over eleven billion years ago, the rate was twenty times higher.”
He says this presents something of a puzzle to astronomers.
“Stars are made from hydrogen and so astronomers expected to see the amount of hydrogen in the Universe decline in similar pattern to the rate of star formation, but the amount of hydrogen has been largely unchanged over billions of years.”
However, while stars are hot, the hydrogen clouds in which they are born must be very cold for the clouds to collapse under their own gravity, with the following hydrogen fusion igniting the proto-star. This cold hydrogen cannot be detected with optical telescopes, the main technique astronomers use to measure the amount of gas in the Universe, but by radio telescopes.
By taking the observations of radio telescopes and comparing them to those of optical telescopes, thus measuring the temperature of the gas, Dr Curran has discovered that in fact the amount of cold hydrogen in the universe has in fact decreased in correlation with the lesser amount of stars being formed.
Dr Curran’s discovery may finally explain the stark disagreement between the star formation history and the available fuel. This will be easily verifiable with the forthcoming Square Kilometre Array, which will be the world’s largest scientific instrument.