UVic researchers help discover new dwarf planet

Two University of Victoria-based researchers are part of an international team of astronomers who have discovered a new dwarf planet orbiting in the disk of small icy worlds beyond Neptune.

The new object is roughly one-and-a-half times the size of Vancouver Island (700 km) and has one of the largest orbits for a dwarf planet.

Designated 2015 RR245 by the International Astronomical Union's Minor Planet Center, the object was first sighted this February by JJ Kavelaars, a researcher with the National Research Council’s Herzberg Astronomy and Astrophysics in Victoria and an adjunct professor at UVic.

“JJ asked me to come over and take a look at his screen and there it was—this dot of light,” says Michele Bannister, an astronomer doing postdoctoral research at UVic. “It was moving so slowly that it had to be at least twice as far as Neptune from the sun. Just wonderful.”

The planet was found using the Canada-France-Hawaii Telescope (CFHT) on Maunakea, Hawaii, as part of the ongoing Outer Solar System Origins Survey (OSSOS), a collaboration of 50 scientists at institutes and universities around the world.

“The icy worlds beyond Neptune trace how the giant planets formed and then moved out from the sun. They let us piece together the history of our solar system,” says Bannister. “Almost all of these icy worlds are painfully small and faint, so it’s really exciting to find one that's large and bright enough to study in detail.”  

The team became even more excited when they realized that the object’s orbit takes it more than 120 times further from the sun than Earth.

“Worlds of this size are fascinating because they can potentially tell us what makes an object go from being an unchanging lumpy mashed-together structure of ice and rock to having geological processes that separate and rearrange its material, as happens on Pluto,” says Bannister.

“The size of RR245 is not yet exactly known, as its surface properties need further measurement. It’s either small and shiny, or large and dull.” 

As RR245 has only been observed for one of the 700 years it takes to orbit the sun, where it came from and how its orbit will slowly evolve in the far future is still unknown. Its precise orbit will be refined over the coming years, after which RR245 will be given a name.

The CFHT is operated by the National Research Council of Canada, the Institute National des Sciences de l'Universe of the Centre National de la Recherche Scientifique of France, and the University of Hawaii, with OSSOS receiving additional access due to contributions from the Institute of Astronomy and Astrophysics, Academia Sinica, National Tsing Hua University, and National Science Council, Taiwan.