A Fluffy Disk Around A Baby Star
John P. Millis, PhD for redOrbit.com – Your Universe Online
Astronomers from the Strategic Exploration of Exoplanets and Disks with Subaru Telescope (SEEDS) project, an effort to search out other worlds, has turned its attention to a somewhat unusual source. Using the Subaru Telescope’s High Contrast Instrument for the Subaru Next Generation Adaptive Optics (HiCIAO), scientists were interested in a young star known as Ry Tau (Tauri) located some 460 light-years from Earth.
Around this recently formed star orbits a disk of gas and dust – what astronomers call a proto-planetary disk. The idea is that what researchers are seeing is the remnant of the interstellar gas cloud that formed the star and is now a breading ground for planets.
The international team found the disk has a radius of about 70 astronomical units (one astronomical unit is equal to the average distance from the Sun to the Earth) around the half million-year-old star. Using the scattered light from the disk, astronomers were able to study the structure of the disk. Based on simulations, they found the observed structure is quite different from other examples of similarly aged young stars with disks.
Instead, the team believes the scattered infrared light is emanating from a fluffy upper layer which is nearly transparent, but not quite. They estimate the amount of dust in this layer is roughly equal to half the mass of our Moon. This sounds like a lot, but given the size of the disk, the matter is spread out over an enormous distance.
The perplexing question is why is this layer of matter present in the case of Ry Tau and not in others? Likely it is a remnant of the dust that typically falls onto the star early in its formation, but for some reason has not yet dissipated. It is also possible this thin layer will have some effect on planetary formation.
Forthcoming observations by the Atacama Large Millimeter/Submillimeter Array (ALMA) on these types of objects will shed some light on the subject. This project will allow astronomers to more closely study the ongoing formation of planets within these disks. Perhaps a connection can be found between these fluffy layers and the types or numbers of planets formed.