Free Astronomy Magazine July-August 2016

shaped cavities. The material that became N55, however, managed to survive as a small remnant pocket of gas and dust. It is now a standalone nebula inside the superbub- ble and a grouping of bril- liant blue and white stars — known as LH 72 — also man- aged to form hundreds of mil- lions of years after the events that originally blew up the superbubble. The LH 72 stars are only a few million years old, so they did not play a role in emptying the space around N55. The stars instead represent a second round of stellar birth in the region. The recent rise of a new popu- lation of stars also explains the evocative colours surround- ing the stars in this image. The intense light from the power- ful, blue–white stars is strip- ping nearby hydrogen atoms in N55 of their electrons, caus- ing the gas to glow in a char- acteristic pinkish colour in visi- ble light. Astronomers recognise this tell- tale signature of glowing hy- drogen gas throughout gal- axies as a hallmark of fresh star birth. While things seem quiet in the star-forming re- gion of N55 for now, major changes lie ahead. Several mil- lion years hence, some of the massive and brilliant stars in the LH 72 association will them- selves go supernova, scatter- ing N55’s contents. In effect, a bubble will be blown within a superbubble, and the cycle of starry ends and beginnings will carry on in this close neigh- bour of our home galaxy. This new image was acquired using the FOcal Reducer and low dispersion Spectrograph (FORS2) instrument attached to ESO's VLT. It was taken as part of the ESO Cosmic Gems program- me, an outreach initiative to produce images of interest- ing, intriguing or visually at- tractive objects using ESO telescopes for the purposes of education and public out- reach. The programme makes use of telescope time that cannot be used for science observa- tions. All data collected may also be suitable for scientific purposes, and are made avail- able to astronomers through ESO’s science archive. A beautiful instance of stellar ornamentation I n this image from ESO’s Very Large Telescope (VLT), light from blazing blue stars en- ergises the gas left over from the stars’ recent formation. The result is a strikingly col- ourful emission nebula, called LHA 120-N55, in which the stars are adorned with a man- tle of glowing gas. Astrono- mers study these beautiful displays to learn about the conditions in places where new stars develop. LHA 120-N55, or N55 as it is usually known, is a glowing gas cloud in the Large Magel- lanic Cloud (LMC), a satellite galaxy of the Milky Way locat- ed about 163,000 light-years away. N55 is situated inside a supergiant shell, or superbub- ble called LMC 4. Superbubbles, often hundreds of light-years across, are form- ed when the fierce winds from newly formed stars and shock- waves from supernova explo- sions work in tandem to blow away most of the gas and dust that originally surrounded them and create huge bubble- by ESO n