Astronomers have discovered a new dwarf planet in our Solar System, which they have informally named DeeDee, and it is so great a distance from the centre of our Solar System that Sun would look like a very bright star from it.
Discovered by astronomers at University of Michigan in collaboration with scientists from the Dark Energy Survey, the new dwarf planet was spotted using the powerful digital camera called DECam on a 4-meter telescope in Chile. The dwarf is located at a distance of roughly 8.5 billion miles from the sun, or 92 astronomical units. One astronomical unit is the distance from the sun to Earth. Only the Pluto-sized dwarf planet Eris is currently more distant, though other minor planets with off-centered orbits spend most of their time even further out.
Astronomers who discovered the planet forwarded the details about the new dwarf planet to the Minor Planet Center, which is responsible for naming and tracking minor planets, comet and moons. The planet has been given a designation—2014 QZ224—but after its orbit has been refined for several more years, the researchers can propose an official name. In the meantime, they’ve dubbed it DeeDee, short for distant dwarf.
The DES images are sensitive enough to detect the reflected sunlight from the new object, which is as faint as a single candle 100,000 miles away and that’s why astronomers used the same tool to take a look at our cosmic neighbourhood as well. The data indicate that DeeDee is between 200 and 800 miles in diameter, meaning it is probably large enough to qualify as a dwarf planet. The researchers expect to obtain a much better estimate of its size from an image they recently obtained with the Atacama Large Millimeter/submillimeter Array telescope in Chile. The researchers expect to complete this analysis and publish the results by mid-November.
To identify DeeDee, the researchers looked through thousands of images to find moving objects in orbit around the sun, against the background of millions of stars and galaxies that remain in the same place from night to night. Gerdes likens this to “finding a really small needle in a really big haystack.”
The researchers don’t look for planets with their eyes. Thousands of computers at Fermilab were used to analyze hundreds of terabytes of data, a process that would have taken more than 300 years on a single computer. Researchers subtract every image taken by DECam from every other image from the same piece of the sky giving scientists a view of the objects that might be moving. This analysis still left the researchers with millions of “dots,” and many more possible ways to connect them. Computer programs developed by University of Michigan team involved with the study took several more months to perform that task. Their code identified DeeDee this summer.
The researchers say the discovery of the icy, faraway world shows that their technique is a promising approach for finding “Planet Nine”—a massive body hypothesized to reside around 600 times farther from the sun than Earth. The existence of Planet Nine would explain the elongated, aligned orbits of a group of distant minor planets similar to, but not including, this newly discovered one.