- 4396 - MILKY WAY GALAXY - A new map of the magnetic fields at the Milky Way's center charts never-before-seen features, and raises new questions about how our galaxy's central engine works.
---------------------------------------- 4396 -
MILKY WAY GALAXY
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- The Milky Way is our home galaxy, but how
well do we actually know it? The new map
of the central region of the Milky Way, which took four years to assemble,
reveals the relationship between magnetic fields at the heart of our galaxy and
the cold dust structures that dwell there. This dust forms the building blocks
of stars, planets, and, ultimately, life as we know it. The central engine of
the Milky Way drives this process.
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- The findings also have implications beyond
our galaxy, offering glimpses of how dust and magnetic fields interact in the
central engines of other galaxies.
Understanding how stars and galaxies form and evolve is a vital part of
the origin story of life. Until now, the
interaction of dust and magnetic fields in this process has been overlooked,
especially within our own galaxy.
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- The center of the Milky Way and most of the
space between stars is filled with a lot of dust, and this is important for our
galaxy's life cycle. What we looked at
was light emitted from these cool dust grains produced by heavy elements forged
in stars and dispersed when those stars die and explode.
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- In the heart of the Milky Way exists a
region called the “central molecular zone”, which is packed with an estimated
60 million solar masses of dust. This vast reservoir of dust has a temperature
of around minus 432.7 degrees Fahrenheit. That's just a few degrees above
absolute zero (minus 460 Fahrenheit), the hypothetical temperature at which all
atomic movement would cease.
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- Also located at the heart of the Milky Way
is hotter gas that has been stripped of its electrons, or "ionized,"
and exists as a state of matter called "plasma." Radio wave observations of this region have
these beautiful vertical elements in them that trace magnetic fields in the
hot, ionized plasma component of the center of the Milky Way.
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- Knowing how this cool dust aligns with the
magnetic fields at the heart of the Milky Way,
would reveal how these magnetic fields are orientated. Such orientation
is referred to as their "polarization."
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- The directions of the magnetic field vary
all across the clouds at the center of the Milky Way. This is the first step in trying to figure
out how the field that we see in the radio waves across these large organized
filaments may relate to the rest of the dynamics of the center of the Milky
Way.
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- Astronomer discovered a powerful 'black hole
wind' that blew through a nearby galaxy for hundreds of days, crushing star
formation and reshaping the galaxy. Something similar may already have happened
in the Milky Way.
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- A
temperamental black hole is helping scientists learn more about how galaxies
evolve. An outburst from a distant
black hole changed its galactic landscape.
Similar activity may have shaped our own galaxy.
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- “Markarian 817” is a spiral galaxy located
some 430 million light-years from Earth. Like our galaxy, the Milky Way, it has
a massive black hole at its center. Such objects help hold galaxies together,
exerting enough gravity on stars, dust and other material to keep everything
slowly orbiting around a central point.
It occasionally gobbles up some of that matter when it falls too close
to the black hole's event horizon.
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- Rather than steadily consuming the gas and
dust around it, the black hole experienced a "temper tantrum" and
suddenly flung the matter away. This produced a bald patch in the galaxy in
which very few new stars could form. The observation suggests that black holes
may reshape their host galaxies much more than previously thought.
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- The researchers noticed a significant dip
in the amount of X-ray light coming from Markarian 817. They used data from the European Space
Agency's XMM-Newton mission which has an extremely sensitive X-ray space
observatory designed to study galaxy formation.
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- XMM-Newton enabled the team to get to the
bottom of the emissions dip. The
culprit was a sustained gust of ultrafast cosmic wind whipping around the
galaxy's black hole at several percent of the speed of light, obscuring the
X-ray light of the galaxy. While it's fairly normal for black holes to send out
brief "puffs" of gas, such a prolonged storm which lasted several
hundred days had not been observed before.
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- When the dust finally settled, the team saw
that the region of Markarian 817 immediately around its black hole had been
largely cleared of dust. This helps unlock a key part of the process of galaxy
formation.
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- Black holes can kill star formation in
wide swaths of the galaxies they inhabit, changing the shape of those
galaxies. This finding could even explain the peculiar bald patch
surrounding our own galaxy's supermassive black hole, Sagittarius A*.
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March 20, 2023 MILKY
WAY GALAXY 4396
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--------------------- --- Wednesday, March 20,
2024
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