The galaxy is a filthy place. With bits and debris lingering everywhere, it is very difficult for scientists to see neighboring planets and stars. But, a new 3D map of stardust revealed in a study published in The Astrophysical Journal on Wednesday will help them navigate through the cosmic thicket and make new discoveries along the way.
Edward F. Schlafly, a Hubble Fellow in the Physics Division at the Lawrence Berkeley National Laboratory, has created the map using data from Pan-STARRS, a pair of telescopes based in Hawaii and APOGEE, a near-infrared spectrograph based in New Mexico.
Pan-STARRS uses a high-resolution camera to photograph the northern night sky on a near-constant basis. It can see the distance between stars, based off of temperature. In 2016, four years worth of images were compiled to create a complete map of the northern night sky; like an astronomical catalog to help scientists understand our place in the Milky Way.
“If you know everything about the stars, you can see exactly what the dust is doing and effectively measure the different distances of stars in the sky and how they vary through the galaxy,” Schlafly tells Inverse.
APOGEE is different than Pan-STARRS in that it cuts through the dust with longer wavelengths of light and shows the temperature, distance, and elemental make-up of stars.
With both tools, Schlafly had enough data to calculate how much dust would be in a region and could locate molecular clouds and nebulae, big dust producers.
The map covers 3,262 light-years of the outer Milky Way, offering an essential tool for Berkeley scientists working on the Dark Energy Spectroscopic Instrument (DESI), which will probe billions of light years into the depths of the universe to construct the first-ever 3-D map of the cosmos. Essentially, the dust map will help DESI know how the light is scattered to more easily locate stars, kind of like its own personal GPS through the Milky Way.
“At a very rough level of approximation, the Milky Way is just a big ball of dust and from all the telescopes we use to observe the universe, we have to get through this ball of dust that we live in,” Schlafly says. “But, as soon as you get outside of it, it’s basically empty and there’s little dust to worry about. So, then, you’re safe, uninhabited all the way out to the galaxy, but you need this map to get through it first.”
DESI will become operational in 2018. In the meantime, Schlafly is racing to complete the dust map in full. As of right now, it only covers about two-thirds of the galaxy, or just the northern sky from Pan-STARRS perspective.
“All the images we have are limited to the northern sky, so if you imagine the telescope sitting on the north pole, it could never see the stars in the south because Earth would always be in the way,” said Schlafly. “So, there’s a big part of the sky we can’t observe. We’ll have to use southern telescopes to map the southern sky.”
Schlafly is hoping to use information from the GAIA orbital telescope that was launched in 2013 to fully complete the map by May.