New images that use data from retired ESA (European Space Agency) and NASA missions show the dust that fills the space between stars in the four galaxies closest to our own Milky Way. The striking photos also provide insight into how dramatically the density of dust clouds within a galaxy can vary.
Cosmic dust has a consistency similar to smoke. It is created by dying stars and is also the material that forms new stars. Space telescopes observe that dust clouds are constantly shaped and molded by the effects of bursting stars, stellar winds and gravity, according to NASA. It also notes that understanding this cosmic dust is the key to understanding our own universe.
The work of ESA’s Herschel Spacecraft Observatory, which operated from 2009 to 2013, made the new observations possible. The supercooled instruments were able to detect the thermal glow of the dust emitted as infrared light. Herschel’s images of cosmic dust gave views of the finer details in these clouds.
But the way telescopes could not detect light from more diffuse clouds, especially in the outer regions of galaxies, where gas and dust are sparse.
This meant that Herschel missed up to 30 percent of all light emitted from dust in nearby galaxies. To fill in the gaps in the dust maps created using Herschel, the astronomers used data from three retired missions: ESA’s Planck Observatory and NASA’s Infrared Astronomical Satellite (IRAS) and the Cosmic Background Explorer (COBE).
In the images, you can see the Andromeda Galaxy (known as M31), the Triangulum Galaxy (M33) and the Large and Small Magellanic Clouds, which are dwarf galaxies orbiting the Milky Way and not the spiral structures of Andromeda and Triangular Galaxies. These four galaxies are within three million light years from our planet.
According to NASA’s JPL Lab, the red color in the pictures indicates hydrogen gas. The empty space bubbles in the images indicate regions where stars recently formed and their immediate wind caused the surrounding dust and gas to blow away. Green light around the edges of the bubble indicates the presence of cold dust accumulated as a result of those winds. The hot dust shown in blue indicates where stars are forming and other processes that may be heating the dust.
Carbon, oxygen, iron, and other heavy elements can become trapped in dust particles, and the presence of these different elements changes the way the dust absorbs starlight. “These improved Herschel images show us that the dust ‘ecosystems’ in these galaxies are very dynamic,” Christopher Clark, an astronomer at the Space Science Telescope Institute in Maryland and leader of the work on creating these images, said in a press statement. ,
Scientists studying interstellar space and star formation are trying to better understand these ongoing cycles. The newly created images showed that the dust-to-gas ratio can vary by up to a factor of 20 within a galaxy, much higher than previously estimated.