- 4506 - UNIVERSE'S OLDEST STARS? - The oldest stars in the universe were 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.
--------- ----------------------- 4506
- UNIVERSE'S OLDEST
STARS?
-
- 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 which is 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.
-
- Group of 60 ultra-faint stars orbiting the
Milky Way could be new type of galaxy never seen before 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.
-
- The new discovery of 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, the students 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. These stars were likely ripped from other
galaxies by the Milky Way. nBased on the
stars' compositions, researchers also believe that each star was ripped from a
different galaxy.
-
- Another 65 retrograde stars have similarly
simple compositions. These stars will now be studied further to determine if
they are also SASS stars.
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-
June 13, 2024 UNIVERSE'S
OLDEST STARS? 4506
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--------------------- --- Friday, June 21, 2024
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