New York: A team of astronomers who have shaded about 87 percent of the southern sky have not yet found traces of planet nine in our solar system.
Pluto, discovered in January 1930, was formerly known as Planet Nine. In 2006, however, astronomers reclassified Pluto as a dwarf planet.
While astronomers continue to suspect that there may be a hitherto unknown planet 9 in the distant solar system, the new search at millimeter wavelengths has not found a convincing candidate.
Led by Sigurd Naess of the Institute of Theoretical Astrophysics of the University of Oslo, astronomers have been tracking the planet using data from a 6-meter Atacama Cosmology Telescope (ACT) in Chile.
Although ACT was developed to study cosmic microwave background radiation, its relatively high angular resolution and sensitivity make it suitable for this type of search.
The astronomers scanned about 87 percent of the sky accessible from the southern hemisphere over a six-year period, and then processed the millimeter images using a variety of techniques, including binding and stacking methods, which can detect weak sources but at the expense of the Losing position information.
“The search found many preliminary candidate sources (about 3,500 of them) but none could be confirmed, and there were no statistically significant detections,” the team said in a statement.
“Scientists, however, were able to exclude a Planet 9 with 95 percent confidence with the above-estimated properties within the surveyed region, results that are generally consistent with other zero search for Planet 9,” it added.
Astronomers also believe that a hitherto undiscovered planet must be lurking in the outer regions of the solar system, perhaps in the huge Oort cloud of objects, which hundreds of astronomical units (au) of the Sun begin to extends to the outside.
According to estimates, the speculative “Planet 9”, about 5-10 Earth masses large and orbits about 400-800 au of the Sun.
But “a planet at this distance would be extremely difficult to see in normal optical sky due to its weakness, even in telescopes like PanSTARRS and LSST,” the team noted.
While the new results cover only about 10-20 percent of the possibilities, other sensitive millimeter devices are coming online and should complete this search for Planet 9 as hypothetical, astronomers have found.
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