# 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 -
FROM PROTOSTARS TO PROTOPLANETARY DISKS 1

# DCO$^{+}$: tracer of X-ray ionization in the inner warm disk surface

## Speakers

• Dr. Cecile FAVRE

## Content

Determination of the D/H ratios is valuable for understanding the chemical and physical conditions at earlier phases of protoplanetary disks formation, in which planets formation may occur. Understanding deuterium fractionation is thus key to explain the D/H distribution pattern found in the various bodies of our solar system. To investigate the different key gas-phase deuteration pathways that can lead to the formation of DCO$^{+}$, we have modeled the chemistry of DCO$^{+}$ in protoplanetary disk [1]. I will present some of these results. In particular, our modeling shows that the recent update in the exothermicity of the reaction involving CH2D$^{+}$ as a parent molecule of DCO$^{+}$ favors deuterium fractionation in warmer conditions (T $\ge$ 50 K) [2]. Our analysis shows that the formation of DCO$^{+}$ is enhanced in the inner warm surface layers of the disk where X-ray ionization occurs. Our findings suggest that DCO$^{+}$ is a tracer of X-ray ionization of the inner disk but not of the CO snow-line.

[1] Favre et al. (2015), The Astrophysical Journal Letters, 802, L23

[2] Roueff et al. (2013), Journal of Physical Chemistry A, 117, 9959