Herschel and Hubble composite image of the Crab Nebula
This image shows a composite view of the Crab Nebula, an iconic supernova remnant in our Galaxy, as viewed by ESA's Herschel Space Observatory and the NASA/ESA Hubble Space Telescope.
A wispy and filamentary cloud of gas and dust, the Crab Nebula is the remnant of a supernova explosion that was observed by Chinese astronomers in the year 1054.
The image combines Hubble's view of the nebula at visible wavelengths, which was obtained using three different filters sensitive to the emission from oxygen and sulphur ions and is shown here in blue, with Herschel's far-infrared image, which reveals the emission from dust in the nebula and is shown here in red.
While studying the dust content of the Crab Nebula with Herschel, a team of astronomers have detected emission lines from argon hydride (ArH+), a molecular ion containing the noble gas argon. This is the first detection of a noble-gas based compound in space.
A comparison of the Herschel data with observations of the Crab Nebula performed at other wavelengths revealed that the regions where they had found ArH+ also exhibit higher concentrations of ions of argon (Ar+) and hydrogen molecules (H2). There, Ar+ can react with H2 forming argon hydride and atomic hydrogen.
The Herschel image is based on data taken with the PACS instrument at a wavelength of 70 microns; the Hubble image is based on archival data from the Wide Field and Planetary Camera 2 (WFPC2).