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摘要
Deep photometry of the Small Magellanic Cloud (SMC) stellar periphery (R = 4 degrees, 4.2 kpc) is used to study its line-of-sight depth with red clump (RC) stars. The RC luminosity function is affected little by young (less than or similar to 1 Gyr) blue-loop stars in these regions because their main-sequence counterparts are not observed in the color-magnitude diagrams. The SMCs eastern side is found to have a large line-of-sight depth (similar to 23 kpc) while the western side has a much shallower depth (similar to 10 kpc), consistent with previous photographic plate photometry results. We use a model SMC RC luminosity function to deconvolve the observed RC magnitudes and construct the density function in distance for our fields. Three of the eastern fields show a distance bimodality with one component at the %26quot;systemic%26quot; similar to 67 kpc SMC distance and a second component at similar to 55 kpc. Our data are not reproduced well by the various extant Magellanic Cloud and Stream simulations. However, the models predict that the known Hi Magellanic Bridge (stretching from the SMC eastward toward the Large Magellanic Cloud, LMC) has a decreasing distance with angle from the SMC and should be seen in both the gaseous and stellar components. From comparison with these models, we conclude that the most likely explanation for our newly identified similar to 55 kpc stellar structure in the eastern SMC is a stellar counterpart of the Hi Magellanic Bridge that was tidally stripped from the SMC similar to 200 Myr ago during a close encounter with the LMC. This discovery has important implications for microlensing surveys of the SMC.
- 出版日期2013-12-20
