Abstract
THE SPECTRUM OF WELLS' COMET.—Dr. B. Hasselberg, of the Observatory of Pulkowa, in a letter to Prof. Tacchini, dated June 30, describes his spectroscopic examination of this comet, the results of which he shows to be of a very exceptional character. The observations were made on the nights of June 4, 5, and 7. The brightness of the nights at Pulkowa in the summer had influenced unfavourably his spectroscopic observa-vations of the great comet of 1881, and the position of Well's Comet was also a disadvantage, so that he had not expected a prominent spectrum, and the more because observations by Prof. Tacchini and Dr. Vogel at the commencement of April did not promise much. His surprise was therefore the greater on finding a very bright and extended continuous spectrum of the nucleus, with an excessively strong yellow line, of which the micrcmetrical measures proved the perfect identity with the yellow line of sodium, line D of the solar spectrum. This was a result altogether new in cometary spectroscopy, and the more noteworthy because at the same time there were no traces of the three ordinary bands of the spectrum. It is confirmed by Duner, Bredichin, and Vogel. In the middle of May, on the contrary, Vogel's observations show that the three bands were then pre sent, though faint, while of the sodium line there was not the least trace. It is therefore necessary to conclude that during the last fortnight of this month the spectrum of the comet had changed in a manner of which the history of the science furnishes ono precedent. Dr. Hasselberg then explains his views of the modus operandi of these changes, and concludes:—“Je crois, o done, que dans le cas actuel, la chaleur solaire n'a joué autre rôle que de faire évaporer le sodium contenu dans la comète, et que les phénomènes lumineux et spectraux observés ont été provoqués et éntretenus principalement par des décharges électriques mises en jeu sous I'influence du soleil.”
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Our Astronomical Column . Nature 26, 344 (1882). https://doi.org/10.1038/026344b0
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DOI: https://doi.org/10.1038/026344b0