What is the oldest star in the universe? What about the youngest?

The oldest known star, officially called HD 140283 but nicknamed Methuselah, is 190.1 light-years away. The UK’s Anglo-Australian Observatory (AAO) Schmidt telescope photographed the star in blue light for the Digitized Sky Survey. (Image credit: Digitized Sky Survey (DSS), STScI/AURA, Palomar/Caltech and UKSTU/AAO)

Among the countless stars that shine in the vastness of space, some are so old that they have experienced the dawn of the universe, and others are so young that not even the most powerful telescopes on Earth have been able to observe them. But is it possible to know which star is the youngest and which is the oldest?

The youngest star in our universe is difficult to identify because stars are constantly being born, but there are a few candidates among the ones we know of. In contrast, scientists have known about the oldest star on record, appropriately nicknamed Methuselah, for decades.

Stars are born inside huge clouds of dust and gas known as nebulae. According to POT (opens in a new tab), some gas clusters in the nebula are loaded with so much material that their own gravity forces them to collapse (since more mass means more gravity), and the strong gravitational pull at the center of a collapsing cloud causes the gas, mainly hydrogen, to accumulate in what becomes a protostar. These embryonic stars begin to fuse hydrogen nuclei into helium, emitting radiation in the process. A star can’t be called a star until it radiates energy, which is how it becomes so incredibly bright. Some faint stars are just coming to life.

New stars are forming all the time, but in 2022 astronomer Ruobing Dong and his colleagues captured images of embryos of a young star in the binary star system constellation Z Canis Majoris. Perturbations from a cosmic interloper were captured by the Subaru Telescope, the Karl G. Jansky Very Large Array, and the Atacama Large Millimeter/submillimeter Array. (Image credit: ALMA (ESO/NAOJ/NRAO), S. Dagnello (NRAO/AUI/NSF), NAOJ)

Astronomer Ruobing Dong (opens in a new tab), an assistant professor in the Department of Physics and Astronomy at the University of Victoria in Canada, has observed these nascent stars. He led a 2022 study in the journal Nature Astronomy. (opens in a new tab) in a binary system of protostars thought to be only about a million years old. Dong and his colleagues were able to put a rough age on some of these star embryos. They often throw tantrums, also known as accretion outbursts.

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