High above the spiral Milky Way, astronomers have spotted two clusters of new stars growing at the fringes of our galaxy. The discovery, led by Denilso Camargo of the Federal University of Rio Grande do Sul in Porto Alegre Brazil, published in the journal Monthly Notices of the Royal Astronomical Society, appears to be the first such stellar cradles found outside the galactic disk.
The Milky Way, the galaxy we live in, has a barred spiral shape, with arms of stars, gas and dust winding out from a central bar. Viewed from the side, the galaxy would appear relatively flat, with most of the material in a disk and the central regions.
Using data from NASA’s Wide-field Infrared Survey Explorer, or WISE, astronomers have found these a cluster of stars. “A stellar nursery in what seems to be the middle of nowhere is quite surprising,” said Peter Eisenhardt, the project scientist for the WISE mission at NASA’s Jet Propulsion Laboratory in Pasadena, California. “But surprises turn up when you look everywhere, as the WISE survey did.”
If any planets were to form around these stars, inhabitants would see the entire glory of the spiral galaxy above them in their night sky.
Previously, it was only thought possible for stars to form inside giant molecular clouds (GMC) located in the inner part of the galactic disc. Within these clumps, many stars are born together in clusters.
Dr Camargo and his team discovered several GMCs above and below the disc of our Milky Way. But they were shocked to find that one GMC 16,000 light-years from the galactic centre contained two clusters of stars forming. Their location is towards the outer limits of our galaxy – far enough that they would see the entire splendour of its spiral above them, but not so far that they are not classified as being in the Milky Way.
Denilso believes there are two possible explanations for these clusters location. First could be the Chimney Model according to which violent events such as supernova explosions eject dust and gas out of the galactic disk. The material then falls back, in the process merging to form GMCs.
The other idea is that the interaction between our Galaxy and its satellites, the Magellanic Clouds, may have disturbed gas that falls into the Galaxy, again leading to the creation of GMCs and stars.
“Our work shows that the space around the Galaxy is a lot less empty that we thought. The new clusters of stars are truly exotic,” Denilso said.
‘Now we want to understand how the ingredients for making stars made it to such a distant spot. ‘We need more data and some serious work on computer models to try to answer this question.’
Bottom line: The WISE mission was selected competitively under NASA’s Explorers Program managed by the agency’s Goddard Space Flight Center in Greenbelt, Maryland. The science instrument was built by the Space Dynamics Laboratory in Logan, Utah. The spacecraft was built by Ball Aerospace & Technologies Corp. in Boulder, Colorado. Caltech manages JPL for NASA. More information is online at: http://www.nasa.gov/wise