The universe is producing fewer stellar "babies." Over the past 4.5 billion years, the rate at which new stars form has fallen to less than half its previous level. Yet the supply of one of the most important types of "fuel" for star formation has changed surprisingly little.
That finding comes from an international research team led by scientists from the Chinese Academy of Sciences (CAS), working with the Dark Energy Spectroscopic Instrument (DESI) project. Using China's Five hundred meter Aperture Spherical radio Telescope (FAST), the researchers made precise measurements of cosmic neutral atomic hydrogen across the past 4.5 billion years.
Their results show a striking mismatch. Star formation has declined sharply, while the amount of neutral atomic hydrogen (HI), an important reservoir of gas within galaxies, has decreased only modestly.
The findings were published online in Nature Astronomy on Sept. 1.
Why Is the Universe Making Fewer Stars?
