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Paper: A Cold Nearby Cloud in the Local Bubble
Volume: 365, SINS — Small Ionized and Neutral Structures in the Diffuse Interstellar Medium
Page: 97
Authors: Meyer, D.M.
Abstract: The high-latitude Galactic H I cloud toward the extragalactic radio sources 3C 225 and 3C 237 is characterized by very narrow 21 cm emission and absorption indicative of an H I spin temperature of about 20 K. Through high-resolution optical spectroscopy, we have recently detected strong Na I absorption corresponding to this cloud toward a number of nearby stars. Assuming that the turbulent H I and Na I motions are similar, we derive a cloud temperature of 20 K and a turbulent velocity of 0.4 km s−1 from a comparison of the H I and Na I absorption linewidths. We can also place a firm upper limit of 45 pc on the distance of the cloud, which places it well within the Local Bubble in this direction.
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