Programme

P.1 -- Poster, NCTP-39

Date: Tuesday, 29-07-2014

Time: 10h30 - 12h00

The influence of turbulent velocity in the circumstellar envelope on the maser line profile

Tran Ngoc Hung, Dinh Van Trung

Institute of Physics

Intense maser emissions by several molecules such as H2O and OH have been commonly observed in the outer region of the expanding circumstellar envelope around evolved stars. High resolution observations indicate that the maser profile has broad double-peak with significant emission at the systemic velocity. In addition, the spatial distribution of the emission is the systemic velocity of the system is also broad. These observational characteristics have been found to be difficult to reproduce with the standard model of the spherically symmetric and smoothly expanding circumstellar envelope. We have carried out large simulations of the maser emissions from circumstellar envelopes which take into account the strong turbulent motion of the gas. The degree of saturation is significantly reduced in the presence of turbulent motion and the double-peaked maser profile is also broadened as expected. Therefore, the large turbulent motion within the circumstellar envelope might provide a viable explanation to the observed characteristics of the maser emission.

Presenter: Trần Ngọc Hưng