Some of the coolest worlds ever seen have been found in our cosmic backyard

19 Aug 2020

Artist’s impression of the oldest known wide-separation white dwarf and cold brown dwarf pair found in this study. Image: NOIRLab/NSF/AURA/P Marenfeld/William Pendrill

Citizen scientists and astronomers have found around 100 cool worlds close to our own solar system.

Astronomers and citizen scientists have uncovered a new haul of worlds, some of which are close in temperature to Earth. The discovery was made using the US National Science Foundation’s NoirLab facilities, in conjunction with the data-mining citizen science project Backyard Worlds: Planet 9.

This latest census found approximately 100 brown dwarfs – objects more massive than planets but lighter than stars. Brown dwarfs lack the mass needed to sustain nuclear reactions in their core, making them very faint objects that can be extremely difficult to detect.

Several of these newly discovered worlds are among the coolest seen to date, including some possibly cool enough to harbour water clouds. Some were also discovered in what we could describe as our cosmic backyard, at just 23 light-years away from the sun, while others were as far as 60 light-years away.

‘Solar neighbourhood is still uncharted territory’

“These cool worlds offer the opportunity for new insights into the formation and atmospheres of planets beyond the solar system,” said Aaron Meisner, lead author of the research paper documenting this discovery.

“This collection of cool brown dwarfs also allows us to accurately estimate the number of free-floating worlds roaming interstellar space near the sun.”

Approximately 100,000 citizen scientists form the Backyard Worlds project and the volunteers on this project inspected trillions of pixels of telescope images to identify the subtle movements of brown dwarfs and planets. So far the project has detected more than 1,500 cold worlds near the sun.

Co-author of the paper, Jackie Faherty of the American Museum of Natural History, said: “This paper is evidence that the solar neighbourhood is still uncharted territory and citizen scientists are excellent astronomical cartographers.

“Mapping the coldest brown dwarfs down to the lowest masses gives us key insights into the low-mass star formation process while providing a target list for detailed studies of the atmospheres of Jupiter analogues.”

Colm Gorey was a senior journalist with Silicon Republic