Sublime image reveals superbubbles, star formation, and satellite galaxies
A stunning image of blazing blue stars and gentle swirls of pink and yellow interstellar gas clouds is gracing our screens, courtesy of the European Southern Observatory (ESO).
The picture was made possible by the most advanced optical instrument on the face of our planet, the ESO's Very Large Telescope array (VLT), based in the forbidding heights of Chile's Atacama desert.
The Atacama, one of the driest locations on Earth, is a Mars-like desert practically devoid of life, requiring a special facility to shelter the research scientists. The resulting structure was so unique, blending in with the environment to minimize disruption to astronomical observations, that James Bond’s nemesis in "Quantum of Solace" used it as his hide-out.
But what can the usual work of the Very Large Telescope – soon to be joined by its bigger brother, the European Extremely Large Telescope – actually tell us?
This most recent image tells a story of young stars being born, burning and energizing the gas left hanging in the vacuum of space following their birth. The breathtaking colors of this interstellar gas, known as an emission nebula, gleam through the cosmos, holding critical clues as to the conditions surrounding new star formation.
The arguably unpoetic name chosen for this phenomenon is LHA 120-N55, or, if one is feeling affectionate, simply N55.
Its location is the Large Magellanic Cloud (LMC), a satellite galaxy of the Milky Way. Satellite galaxies add yet another dimension to the usual order of things in the universe: ordinary galaxies, such as the Milky Way, host hundreds of billions of stars, all orbiting the galaxy's center. A satellite galaxy is constructed in exactly the same way, except that it, too, is in orbit, circling another galaxy.
In this case, the LMC orbits the Milky Way, situated about 163,000 light years away.
Within LMC, N55 finds itself situated in a supergiant shell, or what some prefer to call a superbubble – superbubble LMC 4, to be precise.
Superbubbles are vast cavities of space, often hundreds of light-years across, stripped of any gas or dust by the winds of newly formed stars and the searing shockwaves of supernova explosions.
N55 exists in the vast loneliness of this superbubble, formed from a small pocket of gas and dust that somehow managed to avoid the purge and cling to its spot within LMC 4. Yet N55 is not quite alone in this superbubble. Alongside it lies LH72, a grouping of brilliant blue and white stars that represent a second wave of star birth.
This younger group of nearby stars gives N55 its distinctive palette, stripping hydrogen atoms of their electrons and causing the pinkish glow that astronomers now recognize as a sign of fresh star birth.
For now, as the image implies, all is calm in N55. But the future holds a different story. Millions of years hence, some of the massive, brilliant stars of the LH72 association will go supernova, and the contents of N55 will be scattered.
"In effect, a bubble will be blown within a superbubble," as the ESO describes it, "and the cycle of starry ends and beginnings will carry on in this close neighbor of our home galaxy."
