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E. Bowsher, D. Hunter (Lowell Observatory), E. Wilcots, A. Kepley, V. Goad (University of Wisconsin)
We present single dish radio observations of the extended neutral hydrogen distribution in the irregular galaxy Sextans A. Extended HI disks have been observed around several irregulars, and some of those HI distributions exhibit large-scale structure. Huchtmeier, Seiradakis, & Materne (1981) mapped HI around Sextans A with a single-dish telescope and concluded that the HI extends to a diameter of 54\arcmin, about 5 times the optical diameter. However, subsequent VLA observations by Wilcots & Hunter (2002) detected HI only to 18\arcmin\ diameter and approximately half the HI mass. They concluded that the extended HI must be smoother than the VLA D-array could detect. We used the Green Bank Telescope to make a deep map of Sextans A in which no HI would be missed. Our map did not detect significant HI not detected by the VLA map. We did not detect the extended gas shown by Huchtmeier et al. in channel maps, and we conclude that their extended gas was spurious and that Sextans A does not really have significant HI extended beyond twice the optical diameter.
This work was funded by the National Science Foundation through the Research Experience for Undergraduates program at Northern Arizona University under grant 9988007 and through grant AST-0204922 to Lowell Observatory.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.