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Paper: Radio Recombination Line Observations Toward the Massive Star Forming Region W51 IRS1
Volume: 525, Compendium of Undergraduate Research in Astronomy and Space Science
Page: 33
Authors: Jan, M. I.; Roshi, D. A.; Lebrón, M. E.; Pacheco, E.; Ghosh, T.; Salter, C. J.; Minchin, R.; Araya, E. D.; Arce, H. G.
Abstract: We observed radio recombination lines (RRLs) toward the W51 molecular cloud complex, one of the most active star forming regions in our Galaxy. The UV radiation from young massive stars ionizes gas surrounding them to produce H II regions. Observations of the W51 IRS1 H II region were made with the Arecibo 305 m telescope. Of the full 1–10 GHz database, we have analyzed the observations between 4.5 and 5 GHz here. The steps involved in the analysis were: a) bandpass calibration using on-source/off-source observations; b) flux density calibration; c) removing spectral baselines due to errors in bandpass calibration and d) Gaussian fitting of the detected lines. We detected alpha, beta and gamma transitions of hydrogen and alpha transitions of helium. We used the observed line parameters to 1) measure the source velocity (56.6 ± 0.3 km s-1) with respect to the Local Standard of Rest (LSR); 2) estimate the electron temperature (8500 ± 1800 K) of the H II region and 3) derive the emission measure (5.4 ± 2.7 × 106 pc cm–6) of the ionized gas.
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