If you do any housework, you probably hate dust. If you’re an astronomer, your relationship with dust might be a bit more ambivalent. If you want to learn about star and planet formation, then you love stardust. If you are trying to measure precisely how far away galaxies are, then dust is an annoyance.
A new study might make both camps happy. A team of researchers led by Edward Schlafly from Berkeley Lab have released a 3D map of dust in the Milky Way. The goal of this is to help the Dark Energy Spectroscopic Instrument (DESI) to accurately measure the distance of 30 million galaxies. Unaccounted dust would distort those results.
“The light from those distant galaxies travels for billions of years before we see it," Schlafly said in a statement, "but in the last thousand years of its journey toward us a few percent of that light is absorbed and scattered by dust in our own galaxy. We need to correct for that."
The team constructed a high-precision map of the dust concentration and distribution within 1,000 parsecs (3,262 light-years) from Earth. As reported in the Astrophysical Journal, the map suggests that the dust doesn’t behave as expected.
“In denser regions, it was thought that dust grains will conglomerate, so you have more big grains and fewer small grains,” Schlafly added. The map shows that dense dust clouds and light clouds are very similar. "Whatever is driving this is not just conglomeration in these regions.”
This has given astronomers plenty of food for thought," Schlafly said. The behavior of dust is not only important for cosmology, it’s also what makes star systems. Even we are just the longwinded assembly of star dust.
"The message to me is that we don't yet know what's going on," Schlafly said. "I don't think the existing (models) are correct, or they are only right at the very highest densities."
This work is not a complete map of the dust in the Milky Way and a good chunk of it is still missing. The team plans to add a lot more observations and expand this to cover the entire galaxy.