Tomorrow, April 24th, the Hubble Space Telescope will turn 25. For much of that time, it has been a few hundred miles away, providing a peek into the cosmos. It has long exceeded its mission life (good thing too, it's successor will be a decade past its original completion date and 900% over budget, if it even goes up on the latest 2018 date) but that is okay, Hubble shows no signs of letting up.
To celebrate its 25th birthday, we get an image of Westerlund 2, a giant cluster of about 3,000 stars which resides in a raucous stellar breeding ground known as Gum 29, located 20,000 light-years away in the constellation Carina.
The pillars that surround the star cluster Westerlund 2. These pillars are composed of dense gas and dust are a few light-years tall and point to the central cluster. They are thought to be incubators for new stars. Besides sculpting the gaseous terrain, intense radiation from the most brilliant of the cluster stars is creating a successive generation of baby stars. This is a section of the new NASA/ESA Hubble Space Telescope image of Westerlund 2 and its surroundings, released to celebrate Hubble’s 25th anniversary. Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), A. Nota (ESA/STScI), and the Westerlund 2 Science Team
The stellar nursery is difficult to observe because it is surrounded by dust, but Hubble’s Wide Field Camera 3 peered through the dusty veil in near-infrared light, giving astronomers a clear view of the cluster. Hubble’s sharp vision resolves the dense concentration of stars in the central cluster, which measures only about 10 light-years across.
The giant star cluster is only about two million years old, but contains some of the brightest, hottest and most massive stars ever discovered. Some of the heftiest stars are carving deep cavities in the surrounding material by unleashing torrents of ultraviolet light and high speed streams of charged particles, known as stellar winds. These are etching away the enveloping hydrogen gas cloud in which the stars were born and are responsible for the weird and wonderful shapes of the clouds of gas and dust in the image.
The pillars in the image are composed of dense gas and dust, and are resisting erosion from the fierce radiation and powerful winds. These gaseous monoliths are a few light-years tall and point to the central cluster. Other dense regions surround the pillars, including dark filaments of dust and gas.
Besides sculpting the gaseous terrain, the brilliant stars can also help create a succeeding generation of offspring. When the stellar winds hit dense walls of gas, they create shocks, which generate a new wave of star birth along the wall of the cavity. The red dots scattered throughout the landscape are a rich population of forming stars that are still wrapped in their gas and dust cocoons. These stellar foetuses have not yet ignited the hydrogen in their cores to light-up as stars. However, Hubble’s near-infrared vision allows astronomers to identify these fledglings. The brilliant blue stars seen throughout the image are mostly in the foreground.
The image’s central region, containing the star cluster, blends visible-light data taken by the Advanced Camera for Surveys and near-infrared exposures taken by the Wide Field Camera 3. The surrounding region is composed of visible-light observations taken by the Advanced Camera for Surveys.