[meteorite-list] New Distant Dwarf Planet Beyond Neptune (2015 RR245)

[Ron Baalke]

http://www.cfht.hawaii.edu/en/news/NewDwarfPlanet/

New Distant Dwarf Planet Beyond Neptune
Canada-France-Hawaii Telescope
July 11, 2016

[Image]
Discovery images of RR245. The images show RR245's slow motion across 
the sky over three hours (.gif file). Credit OSSOS team.

An international team of astronomers have discovered a new dwarf planet 
orbiting in the disk of small icy worlds beyond Neptune. The new object 
is roughly 700 kilometers in size and has one of the largest orbits for 
a dwarf planet. Designated 2015 RR245 by the International Astronomical 
Union's Minor Planet Center, it was found using the Canada-France-Hawaii 
Telescope on Maunakea, Hawaii, as part of the ongoing Outer Solar System 
Origins Survey (OSSOS).

"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. But almost all of these icy worlds are painfully small 
and faint: it's really exciting to find one that's large and bright enough 
that we can study it in detail." said Dr Michele Bannister of the University 
of Victoria in British Columbia, who is a postdoctoral fellow with the 
Survey.

National Research Council of Canada's Dr JJ Kavelaars first sighted 
RR245 in February 2016 in the OSSOS images from September 2015."There 
it was on the screen...this dot of light moving so slowly that it had 
to be at least twice as far as Neptune from the Sun." said Bannister.

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. 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." 
said Bannister.

[Graphic]
Rendering of the orbit of RR245 (orange line). Objects as bright or brighter 
than RR245 are labeled. The Minor Planet Center describes the object as 
the 18th largest in the Kuiper Belt. Credit: Alex Parker OSSOS team.
The vast majority of the dwarf planets like RR245 were destroyed or thrown 
from the Solar System in the chaos that ensued as the giant planets moved 
out to their present positions: RR245 is one of the few dwarf planets 
that has survived to the present day - along with Pluto and Eris, the 
largest known dwarf planets. RR245 now circles the Sun among the remnant 
population of tens of thousands of much smaller trans-Neptunian worlds, 
most of which orbit's is unseen.

Worlds that journey far from the Sun have exotic geology with landscapes 
made of many different frozen materials, as the recent flyby of Pluto 
by the New Horizons spacecraft showed.

After hundreds of years further than 12 billion km (80 astronomical units, 
AU) from the Sun, RR245 is travelling towards its closest approach at 
5 billion km (34 AU), which it will reach around 2096. RR245 has been 
on its highly elliptical orbit for at least the last 100 million years.

As RR245 has only been observed for one of the seven hundred 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. As discoverers, 
the OSSOS team can submit their preferred name for RR245 to the International 
Astronomical Union for consideration.

"OSSOS was designed to map the orbital structure of the outer Solar System 
to decipher its history." said Prof. Brett Gladman of the University of 
British Columbia in Vancouver. "While not designed to efficiently detect 
dwarf planets, we're delighted to have found one on such an interesting 
orbit".

RR245 is the largest discovery and the only dwarf planet found by OSSOS, 
which has discovered more than five hundred new trans-Neptunian objects. 
"OSSOS is only possible due to the exceptional observing capabilities 
of the Canada-France-Hawaii Telescope. CFHT is located at one of the best 
optical observing locations on Earth, is equipped with an enormous wide-field 
imager, and can quickly adapt its observing each night to new discoveries 
we make. This facility is truly world leading." said Gladman.

Previous surveys have mapped almost all the brighter dwarf planets. 2015 
RR245 may be one of the last large worlds beyond Neptune to be found until 
larger telescopes, such as LSST, come online in the mid 2020s.

OSSOS involves a collaboration of fifty scientists at institutes and universities 
from around the world.

OSSOS is based on observations obtained with MegaPrime/MegaCam, a joint 
project of the Canada-France-Hawaii Telescope (CFHT) and CEA/DAPNIA, and 
on data produced and hosted at the Canadian Astronomy Data Centre. 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, Taiwan.