At the 236th Meeting of the American Astronomical Society (AAS) held in recent days, on this occasion virtually and not in a physical place due to the Covid-19 pandemic, the discovery of the youngest brown dwarf of our cosmic neighborhood was announced. Named W1200-7845, it’s so young that it has a protoplanetary disk, a really interesting discovery because it will allow to study a possible planetary formation around an object that can be considered a failed star. This result came thanks to the Disk Detective program, which allows citizen scientists to examine astronomical images captured by NASA’s WISE space telescope, looking for protoplanetary disks. Its discovery allowed to conduct follow-up observations to study its evolution.
Just over 330 light-years from Earth, the brown dwarf W1200-7845 was discovered in 2016 within a group of about 30 stars. Brown dwarfs are in some ways normal stars’ neglected siblings: these objects are considered failed stars because their mass is not enough to trigger the thermonuclear reactions that make stars so bright. The consequence is that they have very low emissions that make their identification difficult.
In 2014 NASA funded Disk Detective, one of the programs of the Zooniverse platform that allow citizen scientists to participate in various types of scientific research. In this case, NASA also provided the images captured at optical and near-infrared wavelengths by its Wide-field Infrared Survey Explorer (WISE) space telescope in which anyone can search for protoplanetary disks where new planets can form and in some cases they may already be in their formation phase.
W1200-7845 and its protoplanetary disk were among the candidates reported thanks to the Disk Detective program and subsequently passed on to professional astronomers who could verify their nature. In this case, it turned out that it’s indeed a protoplanetary disk which, however, doesn’t surround a normal star but a brown dwarf. New observations were carried out using the Magellan telescope at the Las Campanas Observatory, in Chile, to study W1200-7845 and its protoplanetary disk. They made it possible to establish that they’re part of the group called Epsilon Chamaeleontis, one of the youngest groups of stars in the cosmic neighborhood with an age between 3 and 5 million years.
The normal stars of the Epsilon Chamaeleontis group have already been the subject of studies because relatively close young stars can have protoplanetary disks to study to understand planetary formation mechanisms. Protostars and newborn stars are much brighter than a brown dwarf, so they’re much easier to spot but now W1200-7845 and its protoplanetary disk have been confirmed as well.
Maria Schutte, the graduate student from the University of Oklahoma who participated in the new observations and announced its results, explained that there are not many examples of young brown dwarfs so close to the Sun, so W1200-7845 is an exciting discovery. Its proximity is really important as it’s much less bright than stars, so the closer a brown dwarf is to us, the more detail can be seen.
The researchers intend to continue their observations of the brown dwarf W1200-7845 with other telescopes such as the ALMA radio telescope, which has already been used in various studies of protoplanetary disks. ALMA’s power and sensitivity could make it possible to measure the mass and radius of that protoplanetary disk and obtain information on its composition. This is very useful information to understand how it could evolve.
In a time when machine learning systems are increasingly being used to assist astronomers in research, the collaboration of citizen scientists remains important. For this reason, the Disk Detective program has been updated and the new version includes images from the PanSTARRS survey. The hope is to discover more protoplanetary disks, in particular those nicknamed Peter Pan because they have an age in which they’re supposed to have already formed planets to understand why that didn’t happen. They would offer more information on the evolution of protoplanetary disks and planetary formation processes.
