MessageToEagle.com - The galaxies are regarded as ideal ‘laboratories’ for finding out how the Universe
has evolved since the Big Bang.
Thanks to research from The Australian National University, the mysteries of the evolution of the universe since
the Big Bang are one step closer to being solved.
Astrophysics PhD candidate Mr David Nicholls from the Research School of Astronomy and Astrophysics, part
of the ANU College of Physical and Mathematical Sciences, used the ANU 2.3 metre telescope at the Siding Spring
Observatory to study distant dwarf galaxies.
“At the beginning of the Universe, the only elements around were hydrogen and helium. Big stars formed from
these elements and, as they evolved, burned the hydrogen and helium into an ‘ash’ of heavier elements.
This ash included nitrogen, carbon and oxygen, which are essential for life,” Mr Nicholls said.
“When these big stars ran out of fuel, they blew up in the form of supernovae and mixed the heavier elements
back into the hydrogen clouds. New stars grew from the enriched gas.
But in Dwarf galaxies, this process has happened very slowly,” he said.
“Dwarf galaxies are the equivalent of historical villages. They still have most of their ‘old buildings’
intact, so we know what they were like when they were first built.
On the other hand, in huge cities like Beijing, nearly all the old buildings have been ripped up and you can’t
tell what they were like originally – just like larger galaxies.
Click on image to enlarge
The GOODS field with 18 of the newly discovered colourful dwarf galaxies highlighted. Click for a bigger image. Credit: NASA, ESA and CANDELS
“By studying dwarf galaxies, we can see what the Universe was like long ago. To do this, we measure the light
from the various elements mixed into the hydrogen clouds in the dwarf galaxies, which tells us how enriched they
are and how they have evolved since the Universe began.”
But when he started to analyse his measurements, Mr Nicholls discovered that the data didn’t fit the conventional
theories. He set out to solve the mystery, and made an unexpected discovery.
A dwarf galaxy, some 48 million light years away. The orange blobs are hydrogen gas clouds, the faint blue background
around them, young hot stars. The white dots are distant background galaxies
“I found that the energies of the electrons in the gas clouds were not distributed the way people had always
thought they should be,” he said.
NGC 4449: Star Stream for a Dwarf Galaxy
A mere 12.5 million light-years from Earth, irregular dwarf galaxy NGC 4449 lies within the confines of Canes
Venatici, the constellation of the Hunting Dogs. About the size of our Milky Way's satellite galaxy the Large
Magellanic Cloud, NGC 4449 is undergoing an intense episode of star formation, evidenced by its wealth of young
blue star clusters, pinkish star forming regions, and obscuring dust clouds in this deep color portrait.
It also holds the distinction of being the first dwarf galaxy with an identified tidal star stream, faintly seen
at the lower right. Placing your cursor over the image reveals an inset of the stream resolved into red giant stars.
The star stream represents the remains of a still smaller infalling satellite galaxy, disrupted by gravitational
forces and destined to merge with NGC 4449. With relatively few stars, small galaxies are thought to possess extensive
dark matter halos. But since dark matter interacts gravitationally, these observations offer a chance to examine the
significant role of dark matter in galactic merger events. The interaction is likely responsible for NGC 4449's
burst of star formation and offers a tantalizing insight into how even small galaxies are assembled over time. Image Credit & Copyright: R Jay Gabany (Blackbird Obs.),
Insert: Subaru/Suprime-Cam (NAOJ), Collaboration: David Martinez-Delgado (MPIA, IAC), et al.
“I used similar measurements of electron energies made by space probes in our Solar System as the basis
for a new theory about how gases behave in distant galaxies.
“To my surprise, it explained my data and also solved other problems that had remained unexplained for over 40 years.”
Mr Nicholls said his research will allow more accurate measurements of the elements in distant galaxies
and help to explain the evolution of the Universe.
The research is published in The Astrophysical Journal and is available online.
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Blood has been said to fall from the heavens, as well as meat, muscle and flesh.
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