New images show the dust in nearby galaxies, and you’ve never seen them like this

When we see pictures of galaxies outside the Milky Way, we usually look mainly at the light from their stars. But stars are far from the only ingredient that makes up a galaxy. Think of stars as the bits of vegetables in the galactic soup.

So the broth they float in is the intergalactic medium – not empty space but filled with often thin, sometimes dense clouds of dust and gas that float between the stars. Because stars are so much brighter, the dust is usually second fiddle; but that dust from which stars are born, to which stars return, can tell us much about the structure and activity within a galaxy.

utilities, four new images have been released, which shows the distribution of dust in four of the galaxies closest to the Milky Way: the Large and Small Magellanic Clouds, dwarf galaxies orbiting our own; the Andromeda galaxy, a large spiral galaxy located 2.5 million light-years away; and the Triangulum galaxy, a spiral galaxy 2.73 million light-years away.

The Large Magellanic Cloud. †ESA, NASA, NASA-JPL, Caltech, Christopher Clark/STScI, S. Kim/Sejong University, T. Wong/UIUC

Without dust and gas, galaxies as we know them would not exist. Stars are formed when a dense tangle of material in a cold cloud of molecular gas collapses under the influence of gravity and takes in material from the surrounding cloud. When that star dies, it throws its outer material back into the space around it, with the new, heavier elements it fused together during its lifetime.

New stars that are born contain the dust of dead stars, making each successive generation of stars slightly different. We are indeed all made of star material – even the stars.

But the dust is not evenly distributed. Stellar winds, galactic winds and the effects of gravity can all push and shape interstellar dust into complex shapes filled with voids. Mapping the structures and composition of the elements within them is a critical tool in understanding the formation of…well…pretty much anything.

The new images, unveiled at the 240th meeting of the American Astronomical Society, were obtained by the Herschel Space Observatory operated by the European Space Agency between 2009 and 2013. Until Webb’s launch — which has yet to deliver its first scientific images — Herschel was the largest infrared telescope ever launched.

small magellanic cloud herschelThe Little Magellanic Cloud. †ESA, NASA, NASA-JPL, Caltech, Christopher Clark/STScI, S. Stanimirovic/UW-Madison, N. Mizuno/Nagoya University

Like Webb, the ultra-cold operating temperature meant that Herschel could peer into the far infrared and image some of the coldest and dustiest objects in space, down to temperatures around -270 degrees Celsius (-454 degrees Fahrenheit). This includes the cold clouds in which stars are born and the dust in interstellar space.

However, it was less adept at detecting more diffused dust and gas. To fill in the gaps, a team of astronomers led by Christopher Clark of the Space Telescope Science Institute used data from three other retired telescopes: ESAs. Planck and NASA’s infrared astronomical satellite (IRA) and Cosmic Background Explorer (COBE

The results reveal complex interactions in the dust. Hydrogen gas appears in red; that’s the most common element in the universe, so there’s quite a few of them. Cavities in the dust where newborn stars have blown it away with their intense winds appear as empty areas, surrounded by a green glow that indicates cold dust. Blue areas represent warmer dust, heated by stars or other processes.

triangulum galaxy herschelThe Triangle System. †ESA, NASA, NASA-JPL, Caltech, Christopher Clark/STScI, E. Koch/University of Alberta, C. Druard/University of Bordeaux

The images also reveal new information about the complex interactions that take place in interstellar dust, the researchers said. Heavy elements such as oxygen, carbon and iron can often stick to dust grains; in the densest clouds, most of the elements are bound to dust, increasing the dust-to-gas ratio. This can affect the way light is absorbed and re-emitted by dust.

However, violent processes, such as the birth of stars or supernovas, can release radiation that breaks down the dust, sending the heavy elements back into gas clouds. This tilts the dust-to-gas ratio back to gas.

The Herschel images show that proportions in a galaxy can vary up to a factor of 20. That’s much higher than astronomers thought, important information that could help scientists better understand this cycle.

And they are just spectacularly beautiful. Who knew Andromeda soup could be such a dazzling rainbow of color.

#images #show #dust #nearby #galaxies #youve

Leave a Comment

Your email address will not be published. Required fields are marked *