Inclination-angle of the outflow in IRAS 05553+1631: A method to correct the projection effect

摘要

A mapping study of IRAS 05553+1631 was performed with 12CO J=3-2 and 13COJ=2-1 lines observed by the KOSMA 3 m-telescope. A core with a size of 0.65 pcand with a LTE mass of 120 M\odot was defined by the mapping with 13CO J=2-1line. We have identified a bipolar outflow with 12CO J=3-2. For accuracy in thecalculation of outflow parameters, overcoming the projection effect isimportant. We propose a new method to directly calculate the inclination-angle{\theta}. We establish two basic equations with the help of outflow contourdiagram and finally obtain the "angle function" and the "angle equation" toderive {\theta}. We apply our method to the outflow of IRAS 05553+1631, findingthat {\theta}blue is 73\circ and {\theta}red is 78\circ. Compared to theparameters initially estimated under an assumption of 45\circinclination-angle, the newly derived parameters are changed with differentfactors. For instance, the timescales for the blue and the red lobes arereduced by 0.31 and 0.21, respectively. Larger influences apply to mechanicalluminosity, driving force, and mass-loss rate. The comparisons betweenparameters before and after the correction show that the effect of theinclination-angle cannot be neglected.