Chinese scientists rewrite established rule of how stars are formed

‘Unprecedented’ stellar survey shows one of astronomy’s most important concepts is not universal but varies with time

Data collected on nearly 100,000 stars by telescopes in China and Europe was analysed by the researchers

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The results of a study by Chinese scientists are expected to have a major impact on how astronomers interpret the light emitted when the universe was forming its first stars. Photo: Nasa

Published: 8:38pm, 19 Jan 2023

Scientists in China have overturned one of astronomy’s most basic assumptions about the formation of stars, used for decades around the world to calculate the history of galaxies and even the chances of finding dark matter and life outside our solar system.

The researchers in Beijing and Nanjing analysed about 100,000 nearby stars picked out by China’s Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) and the European Space Agency’s Gaia space telescope.

The Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) near Beijing can capture thousands of stars simultaneously. Photo: NAOC

To their surprise, they found low-mass stars – 30 to 70 per cent of the sun’s mass – were much less common billions of years ago than are observed today.

The team’s findings, published on Wednesday in the journal Nature, prove that a classical power law – where a relative change in one quantity results in a proportional relative change in another – called the Initial Mass Function (IMF) is not universal but varies with time.

First proposed in 1955 by Austrian astrophysicist Edwin Salpeter, the IMF is one of the most important concepts in modern astronomy. It describes the demographics of a newly formed galaxy – how many stars of each size are created when their parent gas cloud collapses under gravity.

The IMF underpins astronomers’ understanding of virtually everything, from star formation to the evolution of galaxies, supernova explosions and the behaviour of black holes.

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