“From Before Its Birth” –Oldest, Pristine Stars in Universe Found at Milky Way’s Center

Milky way Center

 

“These pristine stars are among the oldest surviving stars in the Universe, and certainly the oldest stars we have ever seen,” said astronomer Louise Howes at The Australian National University (ANU), currently at Lund University, who was a member of a 2015 team along with the University of Cambridge, about the discovery of of stars that date from before the Milky Way Galaxy formed, when the Universe was just 300 million years old. The stars, found near the center of the Milky Way, are surprisingly pristine, but contain material from an even earlier star, which died in an enormous hypernova explosion. “Our Milky Way galaxy formed around them,” she added.

“The stars have surprisingly low levels of carbon, iron and other heavy elements, which suggests the first stars might not have exploded as normal supernovae,” said Howes. “Perhaps they ended their lives as hypernovae – poorly understood explosions of probably rapidly rotating stars producing 10 times as much energy as normal supernovae.

Fast forward to April 2019, the journal Monthly Notices of the Royal Astronomical Society reported that researchers analyzed a cluster of ancient, dim stars called HP1, located about 21,500 light-years away from Earth in the heart of the Milky Way’s central bulge. Using observations from Chile’s Gemini South telescope and archival Hubble Space Telescope data, the researchers calculated the age of the stars to be roughly 12.8 billion years old — making them some of the oldest stars ever detected in either the Milky Way or the entire observable universe. “HP 1 is one of the surviving members of the fundamental building blocks that assembled our galaxy’s inner bulge,” said Leandro Kerber of the University of São Paulo and Brazil’s State University of Santa Cruz.

Project leader of the 2015 ANU team, professor Martin Asplund, said finding such rare relic stars among the billions of stars in the Milky Way center was like finding a needle in a haystack. “The ANU SkyMapper telescope has a unique ability to detect the distinct colors of anaemic stars – stars with little iron – which has been vital for this search.”

“Strange Glow” –Neutron Stars or Dark Matter Source of Odd Light At Milky Way’s Center?

After the discovery in 2014 of an extremely old star on the edge of the Milky Way, the team focused on the dense central parts of the Milky Way, where stars formed even earlier. The team sifted through about five million stars observed with SkyMapper to select the most pure and therefore oldest specimens, which were then studied in more detail using the Anglo-Australian Telescope near Coonabarabran in New South Wales and the Magellan telescope in Chile to reveal their chemical make-up.

The team also demonstrated that the stars spend their entire lives near the Milky Way center and are not just passing through, a further indication that the stars really are the oldest known stars in the Universe.

The Daily Galaxy, Max Goldberg, via Australian National University and Monthly Notices of the Royal Astronomical Society

Image at the top of the page shows a new picture of the Milky Way, created  by an international team of astronomers who discovered that the Milky Way’s disc of stars becomes increasingly ‘warped’ and twisted the further away the stars are from the galaxy’s center. “We usually think of spiral galaxies as being quite flat, like Andromeda which you can easily see through a telescope,” says Professor Richard de Grijs, an astronomer from Australia’s Macquarie University.