High-resolution spectroscopy of the Seyfert galaxy Mrk 595 in the direction of the Cohen H I high-velocity stream |
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| Authors: | S N Kemp & B Bates |
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| Institution: | Instituto de Astrofísica de Canarias, C/ Via Lactea S/N, E-38200 La Laguna, Tenerife, Spain,;Department of Pure and Applied Physics, The Queen's University of Belfast, Belfast BT7 1NN |
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| Abstract: | We have obtained a spectrum of the Na D lines of the Seyfert galaxy Mrk 595 with a signal-to-noise ratio (S/N) of about 30. The importance of this sightline is that this galaxy lies in a direction close to the highest column densities of the Cohen high-velocity (HV) stream, and hence represents the best opportunity of detecting this stream in interstellar absorption, as previous searches towards stellar targets up to a distance of 600 pc have not been successful. The H I column density in the direction of this galaxy implies that the HV gas should be detectable in absorption in the Na D lines. No such detections are made (at the 3σ level) and we consider possible explanations. Hence previous non-detections towards stars do not necessarily mean that the HV gas is more distant than the stars, and we emphasize that the distance of this high-velocity cloud (HVC), which is a key parameter to the understanding of the nature and origin of this feature, remains unknown and indeed may be difficult to establish. |
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| Keywords: | ISM: atoms ISM: clouds ISM: general ISM: structure galaxies: Seyfert radio lines: ISM |
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