- 4516 - THE OLDEST STARS - are circling our galaxy? - The oldest stars in the universe found hiding near the Milky Way's edge, Astronomers reanalyzed the chemical composition of three stars in the Milky Way's halo and found that they are between 12 and 13 billion years old. They may have also been stolen from other galaxies.
----------------------------- 4516
- THE OLDEST
STARS - are circling our galaxy?
-
- Three alien stars circling the Milky Way
could be some of the oldest ever found in the universe. The ancient celestial
objects may have been among the first to form after the Big Bang and were
likely stolen by our galaxy during gravitational tugs-of-war billions of years
ago.
-
- Researchers reanalyzed three previously
observed stars each located around 30,000 light-years from Earth in the Milky
Way's halo, a massive cloud of stars that orbit beyond our galaxy's main
galactic disk. The basic chemical composition of these stars suggests they are
all between 12 and 13 billion years old, making them almost as old as the
universe itself, which formed around 13.8 billion years ago.
-
- The trio's respective trajectories through
the Milky Way also hint that these stars did not originate in our galaxy but
were instead stolen from the periphery of some of the universe's oldest
galaxies as the Milky Way brushed past them billions of years ago.
-
- The ancient balls of gas, which
researchers have dubbed “Small Accreted Stellar System” (SASS) stars, are part
of our cosmic family tree.
-
- Normally, stars this old can only be studied
by spying on galaxies from the other side of the known universe or by
reverse-engineering ancient stars from their descendants. However, the
discovery of ancient stars on our cosmic doorstep gives scientists a rare
opportunity to study them directly and researchers are now confident there are
more stars like these toward our galaxy's edge.
-
- This revealed the stellar trio, which each
had an unusually low abundance of heavy metals such as iron, strontium and
barium in its atmosphere. One of the
stars had around 10,000 times less iron than the sun.
-
- These heavy metals are forged over eons in
the heart of stars, and are also found in the exteriors of younger stars, which
suck up ingredients that were dispersed by exploding dead stars. The fact that
this trio has few heavy metals, means they were formed before most other stars
had exploded.
-
- The stars' compositions hinted that they
did not originate in the Milky Way. But to confirm this, they traced the
orbital trajectories of the three stars and found that they all had a
retrograde motion, meaning they are circling our galaxy's supermassive black
hole in the opposite direction from a majority of the other stars.
-
- The only way you can have stars going the
wrong way from the rest is if you threw them in the wrong way, meaning that
these stars were likely ripped from other galaxies by the Milky Way.
-
- Astronomers have identified another 65
retrograde stars with similarly simple compositions. These stars will be
studied further to determine if they are also SASS stars.
-
-
June 26, 2024 THE
OLDEST STARS - are
circling our galaxy 4515
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--------------------- --- Sunday, June 30, 2024
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