Speaker
Description
Protostellar envelopes are usually approximated as spherical dense and cold regions around early-type stars during the initial phases of star formation. Such regions can harbour volatile and non-volatile astrophysical ices with desorption temperatures between 20 – 150 K. However, little is known about the role of external irradiation for the survival of ices in protostellar envelopes. In this work, we examine the effects of external irradiation on Elias 29, a Class I protostar, which is surrounded by several Young Stellar Objects as well as by two early B-type stars with luminosities around 1000 – 5000 L$_{\odot}$. We have used the Monte Carlo radiative transfer code RADMC-3D to find the dust temperature and UV mean intensity as it penetrates in Elias 29, leading to photodissociation and ice photodesorption. We calculate the half-life time of prebiotic molecules such as C$_2$H$_4$O$_2$ isomers (methyl formate and acetic acid) and CH$_3$OH embedded in a H$_2$O-ice matrix to understand the chemical complexity in this object. As a result, the external irradiation in Elias 29 is estimated to be $\sim$44$\chi_{ISRF}$, which drives two main effects at envelope: (i) change the snowline of volatile species (O$_2$, N$_2$, CH$_4$ and CO) to a toroidal-shaped form, and (ii) create an shielded region where complex molecules would survive longer lifetimes to be assimilated by the protoplanetary disk.
