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R. Idzi, B.-G. Andersson, A. Uomoto (CAS/JHU)
We present preliminary results of a spectro-photometric mapping of the L1457 (MBM12) molecular cloud. Early determinations of the cloud distance, based on Na I absorption line observations, placed the cloud at a distance of ~65 pc, making it the nearest known molecular cloud. Recent work based on photometry of M-dwarfs has put this result into doubt, yielding a preferred distance of ~275 pc.
We have observed >200 field stars in the direction of the cloud using the Coudé-feed telescope at KPNO for spectral classification data and the SDSS calibration telescope at APO for 5 band photometric data. By combining spectroscopic parallaxes with measurements of the color excess for each star, we can map the three dimensional dust distribution towards the cloud and its surroundings. We find evidence for dust concentrations at both of the previously reported distances, as well as an intermediate distance of ~140 pc. We discuss the implications of these results.