New images show dust in nearby Galaxies like you’ve never seen it like This

(ORDO NEWS) — When we see photographs of galaxies outside the Milky Way, we tend to look at the light from their stars. But stars are far from the only ingredient that makes up a galaxy. Think of the stars as bits of vegetables in a galaxy soup.

The soup in which they swim is the intergalactic medium – not empty space, but filled with often fragile, sometimes dense clouds of dust and gas that drift between stars.

Since stars are much brighter, dust usually plays a secondary role; but this dust, from which stars are born and into which stars return, can tell us a lot about the structure and activity within the galaxy.

Four new images have now emerged showing the distribution of dust in the four closest galaxies to the Milky Way: the Large and Small Magellanic Clouds, dwarf galaxies orbiting our galaxy; the Andromeda Galaxy, a large spiral galaxy 2.5 million light-years away; and the Triangulum Galaxy, a spiral galaxy 2.73 million light-years away.

New images show dust in nearby Galaxies like youve never seen it like This 2 1

Without dust and gas, galaxies as we know them would not exist. Stars are formed when a dense knot of material in a cold cloud of molecular gas collapses under the influence of gravity, drawing in material from the surrounding cloud.

When a star dies, it ejects its outer material back into the space around it, along with the new, heavier elements it put together during its lifetime.

New stars being born include dust from dead stars, making each successive generation of stars a little different. Indeed, we are all made of stardust – even stars.

But the dust is unevenly distributed. Stellar winds, galactic winds, and the effects of gravity can all push and shape interstellar dust into complex void-filled shapes. Mapping these structures and the composition of the elements within them is an essential tool for understanding the formation of… well… almost everything.

The new images, presented at the 240th meeting of the American Astronomical Society, were taken by the Herschel Space Observatory, operated by the European Space Agency, between 2009 and 2013. Prior to the launch of Webb, which had yet to transmit its first scientific images, Herschel was the largest infrared telescope ever launched.

New images show dust in nearby Galaxies like youve never seen it like This 3

Like Webb, its ultra-cold operating temperature means Herschel can look into the far infrared, imaging some of the coldest and dustiest objects in space, down to temperatures around -270 degrees Celsius (-454 degrees Fahrenheit). These include cold clouds where stars are born and dust in interstellar space.

However, he was less adept at detecting more diffuse dust and gas. To fill in the gaps, a team of astronomers led by Christopher Clark at the Space Telescope Science Institute used data from three other retired telescopes: ESA’s Planck, NASA’s Infrared Astronomy Satellite (IRAS), and the Cosmic Background Explorer (COBE).

The results show a complex interaction within the dust. Highlighted in red is hydrogen gas – the most common element in the universe, so there is quite a lot of it.

The cavities in the dust, where the newborn stars have blown it out with their intense wind, appear as empty areas surrounded by a green glow that indicates cold dust. Blue areas represent warmer dust heated by stars or other processes.

New images show dust in nearby Galaxies like youve never seen it like This 4

The images also reveal new information about the complex interactions taking place in interstellar dust, the researchers say.

Heavy elements such as oxygen, carbon and iron often stick to dust grains; in the densest clouds, most of the elements are associated with dust, which increases the dust to gas ratio. This can affect how light is absorbed and re-emitted by the dust.

However, violent processes, such as the birth of stars or supernovae, can produce radiation that destroys dust, releasing heavy elements back into gaseous clouds. As a result, the ratio of dust and gas changes towards gas.

The Herschel images show that the ratio can change up to 20 times in the galaxy. This is much more than astronomers thought, and is important information that could help scientists better understand this cycle.

Plus, they are just stunningly beautiful. Who would have thought that Andromeda’s soup could be such a dazzling rainbow of colors.


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