Astronomers have solved a 40-year mystery on the origin of Magellanic Stream — a ribbon of gas stretching almost halfway around our Milky Way galaxy.
The Large and Small Magellanic Clouds, two dwarf galaxies orbiting the Milky Way, are at the head of the gaseous stream.
Since the stream’s discovery by radio telescopes in the early 1970s, astronomers have wondered whether the gas comes from one or both of the satellite galaxies.
New Hubble observations reveal most of the gas was stripped from the Small Magellanic Cloud about 2 billion years ago, and a second region of the stream originated more recently from the Large Magellanic Cloud. Astronomers, led by Andrew J. Fox of the Space Telescope Science Institute in Baltimore, determined the source of the gas filament by using Hubble’s Cosmic Origins Spectrograph to measure the amount of heavy elements, such as oxygen and sulphur, at six locations along the Magellanic Stream.