- 4426
- MILKY WAY
GALAXY - from birth to today. As galaxies merge and collide, their
hydrogen gas clouds are disrupted, which can create a frenzy of star
birth. Over time, the Milky Way’s long filaments
of gas and dust coalesced and resulted in the modern spiral structure of the
galaxy today.
-
------------------------- 4426 - MILKY WAY GALAXY - from birth to today.
- Astronomers have used the Gaia space
telescope to discover some of the first building blocks of the Milky Way
galaxy: two ancient streams of stars named “Shakti” and “Shiva” that helped our
home galaxy grow and evolve more than 12 billion years ago.
-
- Named after Hindu deities, the star streams
appear to be the remnants of two galaxies that merged with an early version of
the Milky Way between 12 billion and 13 billion years ago when the first
galaxies were forming across the cosmos. The structures are so old that they
formed well before the most ancient parts of the Milky Way’s spiral arms and
central disk.
-
- The Gaia space telescope, launched in 2013
by the European Space Agency, began observing the universe in 2014. Astronomers
have used Gaia’s observations to discover previously unknown structures in the
Milky Way, helping them piece together the history of the galaxy. The
telescope’s dataset has also provided astronomers with the positions, distances
and movements for nearly 2 billion stars in the galaxy.
-
- In 2022 Gaia was used to peer into the
heart of the Milky Way and discovered the oldest stars ever found in the galaxy
during their “galactic archaeology” observations. An analysis of data from
nearly 6 million stars observed by Gaia and the Sloan Digital Sky Survey
revealed two streams that appeared to stand out from the rest.
-
- Shakti and Shiva are near the Milky Way’s
heart, and each stream is estimated to include the mass of about 10 million
suns. Here, the ancient stars are all similar in age, orbital path and
composition, which helped astronomers determine that both streams were likely
threads from an outside source that wove together and became part of the Milky
Way.
-
- The stars there are so ancient that they
lack many of the heavier metal elements created later in the Universe’s
lifetime. These heavy metals are those forged within stars and scattered
through space when they die.
-
- Until now, we had only recognized these
very early fragments that came together to form the Milky Way’s ancient heart.
With Shakti and Shiva, we now see the first pieces that seem comparably old but
located further out. These signify the first steps of our galaxy’s growth
towards its present size.
-
- The Milky Way started out small and grew in
size as it merged with other galaxies, gaining stars as well as hydrogen to
form more stars. Each galaxy has hydrogen gas that aids in the birth of stars.
-
- As galaxies merge and collide, their
hydrogen gas clouds are disrupted, which can create a frenzy of star
birth. Over time, the Milky Way’s long
filaments of gas and dust coalesced and resulted in the modern spiral structure
of the galaxy today.
-
-
April 10, 2023 MILKY
WAY GALAXY - from
birth to today. 4426
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--- to:
------
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------ “Jim Detrick” -----------
--------------------- --- Wednesday, April 10,
2024
---------------------------------
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