100 cool worlds found near the sun

How complete is our census of the Sun’s closest neighbors? Astronomers and a team of volunteers with data-related part of Backyard Worlds: Planet 9, a civilian science project, have discovered about 100 cool worlds near the sun – objects more massive than planets but lighter than stars, known as brown dwarfs .

With the help of WM Keck Observatory at Maunakea in Hawaii, the research team found that several of these newly discovered worlds are one of the coolest known, with a few approaching Earth’s temperatures – cool enough to water clouds hide.

The study will be published in the August 20, 2020 issue of the Astrophysical Journal and is available in preprint format at arXiv.org.

Discovering and characterizing astronomical objects in the vicinity of the sun is fundamental to our understanding of our place in, and the history of, the universe. However, astronomers are discovering new inhabitants of the solar system. The new discovery from the Backyard Worlds bridges a rather low gap in the range of low-temperature brown dwarfs, and identifies a long-sought missing link within the population of brown dwarfs.

“These cool worlds offer the opportunity for new insights into the formation and atmospheres of planets outside the solar system,” said lead author Aaron Meisner of the NOIRLab of the National Science Foundation. “This collection of cool brown dwarfs also enables us to eradicate the number of free-floating worlds orbiting interstellar space close to the sun.

To identify several of the weakest and coolest newly discovered brown dwarfs, UC San Diego’s professor of physics Adam Burgasser and Cool Star Lab researchers use Keck Observatory’s sensitive Near-Infrared Echellette Spectrometer, as NIRES instrument. .

“We used the NIRES spectra to measure the temperature and gases in their atmosphere. Each spectrum is essentially a fingerprint, allowing us to distinguish a cool brown dwarf from other types of stars,” said Burgasser, a co-author of ‘ the study.

Follow-up observations with NASA’s Spitzer Space Telescope, Mont Megantic Observatory, and Las Campanas Observatory also contributed to the estimate of the brown dwarf temperature.

Brown dwarfs lie somewhere between the most massive planets and the smallest stars. When the masses are not needed to retain nuclear reactions in their nuclei, brown dwarfs are sometimes referred to as “failed stars.” Their low mass, low temperature and lack of internal nuclear reactions make them extremely faint – and therefore extremely difficult to detect. Therefore, when searching for the hottest brown dwarfs, astronomers can only hope to detect such objects relatively close to the sun.

To help find the coldest, closest neighbors of our sun, astronomers with the Backyard Worlds project have turned to a worldwide network of more than 100,000 civil scientists. These volunteers inspect vibration pixels of telescopic images closely to identify the subtle movements of nearby brown dwarfs and planets. Despite the advancement of machine learning and supercomputers, there is still no substitute for the human eye when it comes to finding weak, moving objects.

Backyard Worlds volunteers have already discovered more than 1,500 stars and brown dwarfs at the Sun; this new discovery represents about 100 of the coldest in that sample. Meisner says this is a record for any civil science program, and 20 of the civil scientists are named as co-authors of the study.

The availability of decades of astronomical catalogs through NOIRLab’s Astro Data Lab helped make the discovery possible.

“The technical burden of downloading astronomical catalogs of billion-object objects is typically insurmountable for individual researchers – including most professional astronomers,” Meisner said. “Fortunately, the Astro Data Lab’s open and accessible web portal made it easy for Backyard Worlds civil scientists to request massive catalogs for candidates with brown dwarfs.”

NASA’s WISE satellite datasets as well as archival observations of telescopes at Cerro Tololo Inter-American Observatory and Kitt Peak National Observatory were also the key to these brown dwarf discoveries.

“It’s exciting that this could first be detected by a civil scientist,” Meisner said. “The discoveries of the Backyard Worlds show that members of the public can play an important role in reviving our scientific understanding of our solar region.”