AN EAGERLY awaited map of the heavens was released last week. The map is the final product of a survey of the infrared radiation emanating from all sections of the sky, revealing millions of stars and galaxies 鈥� even those hidden behind the dense, dusty axis of the Milky Way.
The images from the Two Micron All-Sky Survey (2Mass) have been compiled into an 鈥渁tlas鈥� of the entire sky, incorporating around half a billion objects. About 90 per cent of these are stars, planets and asteroids in the Milky Way, collected in one catalogue. The remaining objects are in neighbouring galaxies, the most distant about 8 billion light years away, and these are presented in a second catalogue.
The release marks the culmination of the 10-year mapping project, which was a collaboration between the University of Massachusetts and NASA鈥檚 Infrared Processing and Analysis Center at the California Institute of Technology. Astronomers around the world now have online access to the map at irsa.ipac.caltech.edu.
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Stars and galaxies have already been mapped using visible light, but interstellar dust obscures much of our view. Because infrared radiation streams straight through the dusty clouds, the 2Mass survey reveals stars in the farthest reaches of our Galaxy and in parts of the Universe that were previously hidden. And it betters previous infrared surveys because the telescopes used to take the new pictures 鈥� one in Chile, the other in Arizona 鈥� have sharper vision.
快猫短视频s are expected to pounce on the new resource. 鈥淭he American Astronomical Society has about 5000 members, and I think just about every one of them, at one time or another, is going to find a use for this data,鈥� says Martin Skrutskie at the University of Virginia, who is principal investigator on 2Mass.
When preliminary 2Mass data was released in 2000, it prompted a flurry of research, and over 400 papers have since been published. From that initial patchy view of sky, there have already been major discoveries. The bar of matter that runs through the centre of the Milky Way has been mapped for the first time, and a large number of brown dwarf stars 鈥� previously thought to be rare 鈥� have been discovered.
But having all-sky data will make future analyses much more powerful, explains Martin Weinberg, a scientist on the project at the University of Massachusetts. For example, to study the distribution of galaxies in the cosmos you need to see them all. The survey maps the fine structure in the clusters of galaxies and filaments that wind through space.
For Edward Wright at the University of California, Los Angeles, who worked on the Wilkinson Microwave Anisotropy Probe (see 鈥淭he results are in 鈥� and now it鈥檚 time to party鈥�), this is one of its most significant achievements. WMAP surveyed the radiation left over from the big bang 鈥� at much longer wavelengths than 2Mass. It will be very exciting to compare the two surveys, Wright says. While WMAP is a snapshot of the Universe less than half a million years after its birth, 2Mass shows the structure we see now, almost 14 billion years later.
The survey also provides a reference grid that will be used for decades. Although the location of certain stars and galaxies is given more precisely in other catalogues, 2Mass pins down many more objects, filling in the gaps. The Space Infrared Telescope Facility to be launched by NASA later this month 鈥� a sort of Hubble telescope for the infrared spectrum 鈥� will use the 2Mass data to guide its observations.
The new results are also being hailed as a cornerstone for the 鈥渧irtual observatory鈥�, a concept that is expected to change the way astronomy is done. The aim of the virtual observatory is to combine the data from many digital sky surveys into a vast online archive, enabling astronomers anywhere to carry out research without needing access to a telescope. 鈥淭he lone scientist with a pipe, late at night 鈥� that bit of romance is yesteryear,鈥� says Weinberg.
