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Paper: Galactic Small Scale Structure Revealed by the GALFA-H I Survey
Volume: 438, The Dynamic Interstellar Medium: A Celebration of the Canadian Galactic Plane Survey
Page: 126
Authors: Begum, A.; Stanimirović, S.; Peek, J. E. G.; Ballering, N.; Heiles, C.; Douglas, K. A.; Putman, M.; Gibson, S. J.; Grcevich, J.; Korpela, E. J.; Lee, M.; Saul, D.; Gallagher, J.
Abstract: The Galactic Arecibo L-band Feed Array H I (GALFA-H I) survey is mapping the entire Arecibo sky at 21 cm, over a velocity range of –700 to +700 km s-1 (LSR), at a velocity resolution of 0.18 km s-1 and an angular resolution of 3.5 arcmin. The unprecedented resolution and sensitivity of the GALFA-H I survey have resulted in the detection of many isolated, very compact H I clouds at low Galactic velocities which are distinctly separated from the H I disk emission. In the limited area of ∼4600 deg2 searched so far, we have detected 96 such compact clouds. The detected clouds are cold with Tk less than 300 K. Moreover, they are quite compact and faint, with median values of 5 arcmin in angular size, 0.75 K in peak brightness temperature, and 5×1018 cm-2 in H I column density. From the modeling of spatial and velocity distributions of the whole compact cloud population, we find that the bulk of clouds are related to the Galactic disk, and are within a few kpc distance. We present properties of the compact clouds sample and discuss various possible scenarios for the origin of this cloud population and its role in Galactic interstellar medium studies.
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