# From clouds to protoplanetary disks: the astrochemical link

4-8 October 2015
Hans Harnack Haus
Europe/Berlin timezone
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# Contribution Contributed Talk

Hans Harnack Haus -
PROTOPLANETARY DISK EVOLUTION AND SOLAR SYSTEM 1

# Chemical footprint of a nascent planet

## Speakers

• Dr. Asunción FUENTE

## Content

The formation of planetesimals requires that primordial dust grains grow from micron- to km-sized bodies. As dust grains grow, they start to decouple from the gas and drift radially towards the central star. Therefore, planetesimal formation has to happen in time-scales shorter than radial drift. One way to halt the inward drift is by developing a local maximum in the radial surface density of the gas that would act as a dust trap. Dust traps have been identified in transitional disks using the dust continuum emission at longer wavelengths (mm). However their detection remains difficult in molecular lines. Our data show the chemical footprint of the presence of a dust trap in a transitional disk. Sulfur monoxide has been imaged in the transitional disk around the Herbig Ae star, AB Auriga. This species presents an odd spatial distribution with a hole towards the dust trap. This hole is the consequence of the enhanced gas densities within the trap and it is so far the best example of how the gas dynamics, the grain growth and the gas chemistry are coupled. Hydrodynamical simulations couple to a time-dependent chemical model are able to explain the observed trend and prove that the sulphur chemistry can be used as a tool to investigate the planet formation process. SO is the second S-bearing molecule detected in a PPD (the first was CS) and opens the possibility to study the sulphur chemistry in a proto-solar nebula analog. Besides the high level of sulfur in the Sun (S/Si $\sim$0.5), sulfur is widespread in the Earth, the Venusian atmosphere, in the Martian regolith, it is present in Jupiter and Saturn, and is specially abundant in Io. The comprehension of the sulfur chemistry is of paramount importance to understand the formation of our own planetary system.