Oral Abstract

Oral Contribution (O0.6) Alice Booth (Leiden Observatory, Leiden University )

A major asymmetric ice trap in a planet-forming disk

New planetary systems are made from dust and gas in the rotating disks around young stars. Elemental abundances and ratios such as C/O are key quantities in linking planet composition to their formation history. Additionally, the presence of complex organic molecules (COMs) allows for the potential for a planet/moon to produce a habitable environment. In this talk, I will present recent ALMA observations of the warm transition disk Oph-Irs 48. We detect simple molecules sulphur monoxide (SO) and sulphur dioxide (SO2) and more complex species formaldehyde (H2CO) and methanol (CH3OH). These data include the first robust detection of SO2 in Class II disk. The molecular emissions are all co-spatial with the extreme asymmetric dust-trap traced in the millimetre continuum. The detection of these molecules and the high abundance of both CH3OH and volatile sulphur suggests we are seeing the sublimation of ices. We propose that at the irradiated cavity wall the dust temperature is high (>100K) and therefore the full volatile content of the disk is in the gas phase. We show that the gas here has a C/O<1 and potentially solar value. This is in contrast to what ALMA has shown for most disks so far. Typically observations find that disks are depleted in volatile oxygen with an elevated C/O>1. This has important implications for the elemental composition of planets forming within the cavities of warm transition disks compared to those in colder disks.