The iconic "Pillars of Creation" in the Eagle Nebula are vast clouds of gas and dust that are known hide embryonic stars, but astronomers are still working out how the dramatic structures could form.



A new model presented at an astronomy meeting in the UK this week suggests one mechanism. Roving gas clouds will accumulate in shadowy regions where they are most shielded from the intense ultraviolet light of young, hot stars, the research suggests. Over the course of 150,000 years or so, these clouds can merge together to form pillars. The original clouds needed to form such large pillars might need to be especially dense, since some estimates pin the age of the nebula at just 100,000 years old.



Some astronomers suspect a supernova blast might have already blown the pillars away, but because of the time it takes light from the nebula to reach Earth, we will not witness their destruction for another 1000 years. (Image: X-ray: NASA/CXC/U Colorado/Linsky et al.; Optical: NASA/ESA/STScI/ASU/J Hester & P Scowen)

This bubble was spotted in Centaurus A, a galaxy that boasts a supermassive black hole at its core. As matter falls towards the black hole, jets of plasma are thrown out. These inflate large bubbles filled with energetic particles, driving shock waves through the stars and gas that surround the galaxy's core. This creates X-rays and gamma rays that are visible from Earth.



Centaurus A, which sits some 14 million light years away, is thought to be the nearest galaxy to contain such jets. (Image: Chandra X-ray Observatory)

A 100,000-light-year-long fountain of stars, gas, and dust seems to be streaming down from a pair of colliding galaxies (top). The gravitational forces involved have stretched a spiral arm and stoked star formation, creating a bright blue streamer full of newborn, blue stars. A third galaxy (bottom) seems to be connected by this bridge of material, but it is actually in the background and not connected at all.



Together the trio of galaxies are part of a system known as Arp 194 and they sit about 600 million light years away from Earth in the constellation Cepheus. The Hubble Space Telescope's Wide Field Planetary Camera 2, which is set to be replaced next month, took this image, which was released to commemorate the 19th anniversary of the telescope's launch on 24 April 1990. (Image: NASA/ESA/Hubble Heritage Team/STScI/AURA) Advertisement

The final space shuttle mission to service the Hubble Space Telescope passed an important milestone this week, as the Hubble cargo was stowed on the space shuttle Atlantis (foreground).



Since the telescope orbits at an altitude that is more than 100 kilometres higher than the International Space Station, astronauts will not be able to reach the station in case of an emergency. As a result, the Kennedy Space Center in Florida is keeping the space shuttle Endeavour at the ready in case a rescue mission is needed. Both shuttles are now installed on their launch pads, which sit some 2.5 kilometres away from one another. (Image: NASA/Troy Cryder)

A large haul of unusual white dwarfs has been found in an ancient swarm of stars called NGC 6397, which orbits the Milky Way and sits some 7200 light years away in the southern constellation Ara.



White dwarfs, the dense remains of sun-like stars, ordinarily contain carbon and oxygen. But a new study has found 18 white dwarfs that seem to be made of helium. All told, the star cluster NGC 6397 contains two dozen of the unusual helium-core dwarfs.



The stars' positions in the centre of the cluster suggests they are anchored there by heavy, as yet unidentified companions. These companions could have pulled away a lot of material from the stars before the stars became white dwarfs, preventing them from forming heavier elements.



Stellar pairs are thought to play an important role in such globular clusters, stirring up surrounding stars and preventing the core from getting too dense and collapsing to form a large black hole. (Image: Jay Anderson/Space Telescope Science Institute)