FöRFATTARE
Bamrungrak, Kawita

INSTITUTION
Rymdvetenskap, Kiruna /

SAMMANFATTNING
G70 has always been an enigmatic nebula and has stimulated astronomers to propose the most fantastic and exotic explanations. To characterize the interstellar medium (ISM) around G70, we have obtained H I data from the Westerbork radio telescope (WSRT). In this framework, the scope of this study has been to reduce the data, derive key parameters (optical depth, spin temperature and column density) of the surrounding ISM, whose interaction with the source is used to improve our understanding of the object. We reduced the radio data using the dedicated package ‘Astronomical Image Processing System (AIPS)’ in a standard fashion. After the uv-fits files were read into AIPS, we applied a bandpass calibration using calibrator sources 3C147 and 3C286 because the observation was initially well calibrated in both phase and amplitude. The final steps consisted in imaging and self-calibration. Nevertheless, undesired negative parts (black areas) are still left around the source on our image, which are suspected to occur from a difference between the theoretical and the real dirty beam. Subsequently, desired parameters have been deduced and the spectra obtained. Unfortunately, the beam of the H I data was too large to be useful for a more detailed analysis of the morphology and dynamics of the cold neutral ISM around G70. Unlike our expectations, no relationship has been found between the surrounding ISM and the source.

ISSN 1653-0187 / ISRN LTU-PB-EX--08/088--SE / NR 2008:088