They were looking for Planet 9 but ‘Backyard Worlds: Planet 9’ Project found a Cold Brown Dwarf

Artist’s impression of a T-dwarf. Image credit: R. Hurt / NASA

Professional and citizen astronomers with the NASA-funded ‘Backyard Worlds: Planet 9’ project have made their first significant discovery: a new brown dwarf in the solar neighborhood, WISEA J110125.95+540052.8.

The Backyard Worlds: Planet 9 website lets anyone with a computer and an Internet connection flip through images taken by NASA’s Wide Field Infrared Survey Explorer (WISE).

If an object is close enough to Earth, it will appear to ‘jump’ when multiple images taken of the same spot in the sky a few years apart are compared.

The goal for Backyard Worlds volunteers — of which there are more than 38,000 — is to flag the moving objects they see in these digital flipbooks for further investigation by the science team.

“We constructed the citizen science website ‘Backyard Worlds: Planet 9’ using the Zooniverse project builder platform,” Backyard World’s researchers explained. “We uploaded the sets of four difference images to the site to be viewed by users as animated ‘flipbooks’.”

“The classification task consists of viewing one flipbook and searching it for candidate moving objects, then marking any such objects in all four images using a marking tool. A tutorial and a ‘Field Guide’ provide examples of two different kinds of candidate objects, called ‘movers’ (fast-moving sources) and ‘dipoles’ (slower-moving sources).”

This image shows the brown dwarf WISEA J110125.95+540052.8 (centrr). Image credit: Kuchner et al, doi: 10.3847/2041-8213/aa7200.

“The primary challenge for users is distinguishing movers and dipoles from various artifacts, the most common of which are stars and galaxies that have been partially-subtracted because of variability or small alignment errors. Cosmic ray hits, optical ghosts and latent images are also common.”

On February 21, 2017, just six days after the launch of the website, Backyard Worlds volunteer Bob Fletcher, a science teacher at Lambert School in Hobart, Tasmania, noted the existence of a small ‘dipole’ in the flipbook showing the ‘subtile’ centered at R.A. 165.46 degrees, declination 54.03 degrees.

Three other citizen astronomers — Rosa Castro from the United States, Khasan Mokaev from Kabardino-Balkar Republic, and Tamara Stajic from Serbia — also helped classify this flipbook and noted the object.

After some initial investigation, Backyard World’s researchers were awarded time on the 3-m NASA Infrared Telescope Facility, where they confirmed that it was a previously unknown brown dwarf.

“I was so proud of our volunteers as I saw the data on this new cold world coming in. It was a feel-good moment for science,” said Dr. Jackie Faherty, a senior scientist in the American Museum of Natural History’s Department of Astrophysics and one of Backyard World’s researchers.

The newfound brown dwarf, WISEA J110125.95+540052.8, is approximately 111 light-years away. It is just a few hundred degrees warmer than Jupiter and belongs to spectral class T.

“Brown dwarfs are strikingly similar to Jupiter so we study their atmospheres in order to look at what weather on other worlds might look like,” said Dr. Jonathan Gagné, a Backyard Worlds team member from the Carnegie Institution for Science.

Although the team hopes to find the hypothetical Planet Nine, these brown dwarfs are also exciting discoveries.

“It’s possible that there is a cold world closer than what we believe to be the closest star to the Sun,” Dr. Faherty said.

“Given enough time, I think our volunteers are going help to complete the map of our solar neighborhood.”

The discovery is reported in the Astrophysical Journal Letters (arXiv.org preprint).

Sources: sci-news, Wikipedia