Free Astronomy Magazine May-June 2018

MAY-JUNE 2018 T his picture from the NASA/ESA Hubble Space Telescope sets the scene for the story of the hunt for an elusive missing object hidden amid a complex tangle of gaseous filaments in one of our nearest neighbouring galaxies, the Small Magellanic Cloud. The wisps of gas forming the supernova remnant 1E 0102.2-7219 show up in blue near the centre of the picture. Part of the massive star-forming region, N 76, also known as Henize 1956, appears at the lower right in green and pink. [NASA, ESA and the Hubble Heritage Team (STScI/AURA)] tion was known, the team used ex- isting X-ray observations of this tar- get from the Chandra X-ray Obser- vatory to determine that it must be an isolated neutron star, with a low magnetic field. In the words of Frédéric Vogt: “If you look for a point source, it doesn’t get much better than when the Universe quite literally draws a circle around it to show you where to look.” When massive stars explode as su- pernovae, they leave behind a cur- dled web of hot gas and dust, known as a supernova remnant. These tur- bulent structures are key to the redistribution of the heavier ele- ments — which are cooked up by massive stars as they live and die — into the interstellar medium, where they eventually form new stars and planets. Typically barely ten kilometres across, yet weighing more than our Sun, isolated neutron stars with low magnetic fields are thought to be abundant across the Universe, but they are very hard to find because they only shine at X-ray wave- lengths. The fact that the confirma- tion of p1 as an isolated neutron star was enabled by optical observations is thus particularly exciting. Co-author Liz Bartlett, another ESO Fellow in Chile, sums up this discov- ery: “This is the first object of its kind to be confirmed beyond the Milky Way, made possible using MUSE as a guidance tool. We think that this could open up new chan- nels of discovery and study for these elusive stellar remains.” !