Mass loss from α Ori

Extract

High dispersion spectrograms of α Ori are obtained. Several strong absorption lines which have circumstellar components are measured. Assuming the plane-parallel envelope and thermal equilibrium, the mass loss rate is estimated as 1x10^-6 M_ʘ/yr.

To obtain the mass loss rate of red giant stars is very important in connection with the study of the stellar evolution. Several authors have observed circumstellar lines and obtained mass loss rate using precise theories of radiation transfer. However, accuracy of the studies seems to depend not on the adopted theories but on the dispersion of spectrograms, since the structure of the circumstellar space is too complicated to be expressed by,e.g.,single expansion velocity. Because our spectrograms have higher dispersion, compared with others, our study is meaningful, though the assumed model is very simple.