2011MNRAS.413...71K

A mapping study of IRAS 05553+1631 was performed with ¹²CO J= 3 -2 and ¹³CO J= 2-1 lines observed by the KOSMA 3-m telescope. A core with a size of 0.65 pc and with a local thermodynamic equilibrium mass of 120 M_☉ was defined by mapping with the ¹³CO J= 2-1 line. We have identified a bipolar outflow with ¹²CO J=3-2. For accuracy in the calculation of outflow parameters, overcoming the projection effect is important. We propose a new method to directly calculate the inclination angle θ. We establish two basic equations with the help of an outflow contour diagram and finally obtain the `angle function' and the `angle equation' to derive θ. We apply our method to the outflow of IRAS 05553+1631, finding that θ_blue is 73° and θ_redis 78°. Compared to the parameters initially estimated under the assumption of a 45° inclination angle, the newly derived parameters are changed by different factors. For instance, the time-scales for the blue and the red lobes became smaller by 0.31 and 0.21, respectively. Larger influences apply to the mechanical luminosity, driving force and mass-loss rate. Comparisons between parameters before and after the correction show that the effect of the inclination angle cannot be neglected.