Science & Technology (Commonwealth Union) – Inside a vast disc of gas and dust that is referred to as Gomez’s Hamburger, or GoHam, astronomers that applied Chile’s Atacama Large Millimeter/submillimeter Array (ALMA) have discovered what could possibly be the initial signs of a massive planet. The findings appeared in The Astrophysical Journal this month.
The findings were first announced at a news conference during the American Astronomical Society‘s 247th meeting. The form of the system had been the inspiration for the name. From point of view of an individual, GoHam seems like a bun-and-patty stack surrounding a young star since it is almost precisely angled and viewed edge-on. As a result it makes the vertical structure of the disc seen, which is much more harder for identification in discs that are more face-on to humans, this is of great value to scientists.
This could turn out to be a significant development in the world of astronomy.
On the millimetre wavelength, the team mapped the locations of millimeter-sized dust grains and several molecules in the disc. The molecules comprised two forms of carbon monoxide, 12CO and 13CO, and the sulfur-bearing molecules CS and SO.
The arrangement is what theory predicts for a disc sorting itself in height. The lightest carbon monoxide isotopologue, 12CO, is found at the highest altitude above the midplane, with 13CO found at a lower altitude and CS found closest to the midplane. In the middle, the dust settles into a thin sheet. Gas billows far above and below it. The gaseous component of the disc is much more puffy than the larger solid grains.
The disc is not perfectly symmetrical, and the intrigue is in the flaws. The dust emission is asymmetric along the north-south direction, brighter and more extended on one side. The team proposes a vortex or other large-scale disruption may be responsible, one that could trap solids and present more raw material for planet building.
At large distances, faint wispy carbon monoxide in the northern part of the disc may be a sign of a photoevaporative wind. In fact, the star’s radiation slowly blows gas off the disc and into space.
The estimated dust mass is many times higher than in typical disks around similar stars. That suggests enough material to build giant planets and perhaps an entire multi-planet system.
For researchers, the appeal is the combination of size, layering, asymmetry, winds and a possible planetary seed in one object. Models of planet formation can now be compared against a disk that shows all of these features in unusually sharp detail.
ALMA is an international facility run as a partnership between the European Southern Observatory, the U.S. National Science Foundation and Japan’s National Institutes of Natural Sciences, in cooperation with the Republic of Chile. The NSF National Radio Astronomy Observatory is a facility of the NSF, operated under cooperative agreement by Associated Universities, Inc.
