The spectra of comet Arend-Roland (1956h) I. Medium-dispersion spectra

Abstract

This is the first of two papers reporting the spectra of the Comet Arend-Roland (1956h) observed with the 82″ telescope at the McDonald Observatory, Texas, USA. In this paper we report the results of the analysis of two spectra, one in the range$\text{λλ3700}\text{A}\text{̊}\text{− 4800}\text{A}\text{̊}$. Having a dispersion of 36Å/mm and the other, $\text{λλ5100}\text{A}\text{̊}\text{−6800}\text{A}\text{̊}$ having a dispersion of 72Å/mm. (The second paper deals with the polarization of emission lines of the comet). The spectra show a very strong solar continuum shifted to the red because of the Doppler effect, indicating that the comet is very dusty. From the lengths perpendicular to the dispersion of the continuum on the spectrogram, we estimated the linear dimension of the coma of the comet as 4.3 × 10³km.