The role of external FUV irradiation in the survival of astrophysical ices in Elias 29

TL;DR

This study investigates how external FUV radiation influences the survival and chemical composition of astrophysical ices around Elias 29, revealing that external irradiation significantly alters snowline positions and molecular formation processes.

Contribution

It demonstrates that external FUV irradiation from nearby stars dominates local protostars in affecting ices, redefining snowline geometries and impacting complex molecule formation in Elias 29.

Findings

HD 147889 dominates external irradiation, increasing it 44 times the standard value.

FIR spectrum and near-IR images show significant effects due to external irradiation.

Snowline positions are redefined to a toroidal shape, affecting chemical processes.

Abstract

The survival of astrophysical ices in the star-forming regions depends on the suitability of temperature, density and radiation conditions. In this paper, the role of Interstellar Radiation Field (ISRF) on ices in Elias 29 is addressed. This object is the most luminous protostar in $\rho$ Oph E molecular cloud, and is surrounded by many Young Stellar Objects distant only a few arcminutes. In addition, other two brightness BV stars (S1 and HD 147889) enhance the external irradiation in Elias 29. This study was carried out by using the Monte Carlo radiative transfer code RADMC-3D assuming an internal and external irradiation. As result, we found that HD 147889 dominates the ISRF, instead of the closest protostars, and contributes to enhance the external irradiation in 44 times the standard value. Furthermore, remarkable effects are observed in FIR spectrum, as well as in near-IR image. Additionally, the snowline positions of volatile compounds, such as CO, O$_2$, N$_2$ and CH$_4$ are redefined to a toroidal-shaped morphology in the envelope, with low FUV flux (10$^{-7}$ ergs cm$^{-2}$ s$^{-1}$). In such scenario, the formation of complex molecules as result of hydrogenation or oxygenation of volatile species are expected to be severely affected.