Astronomers find 13 billion-year-old signs of early stars

An image of the galaxy cluster MACS J1149.5+2223 taken with the Hubble Space Telescope. Inset image is the galaxy MACS1149-JD1 observed with ALMA. Oxygen detected with ALMA is depicted in green.
Galaxy cluster MACS J1149.5+2223 with galaxy MACS1149-JD1 inset. Oxygen is depicted in green. Image: ALMA (ESO/NAOJ/NRAO), NASA/ESA Hubble Space Telescope, W. Zheng (JHU), M. Postman (STScI), the CLASH Team, Hashimoto et al.

Astronomers have detected oxygen in a galaxy more than 13 billion light years away — a direct measurement of stars forming and dying in the early universe.

The big picture: The time when stars first formed in the universe is of intense interest to researchers. It is the epoch when matter began clumping together into stars and galaxies, heavy elements started to form, and our universe began to look like it does today.

"We have a theory for why that all happened but precious few observations of when it all started to take shape."
Rob Simcoe, astronomer, MIT