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Optical detection of the Galaxy's southern stellar warp and outer disk

1993; Institute of Physics; Volume: 105; Linguagem: Inglês

10.1086/116591

1538-3881

Bruce W. Carney, Patrick Seitzer,

Astrophysics and Star Formation Studies

We report the probable detection of the stellar population in the outer Galactic disk in the direction of the southern Galactic warp. VIc CCD photometry was obtained for four fields toward the southern Galactic warp and four control fields at equal longitudes but opposite latitudes. All fields were chosen to have uniform star densities and galaxies visible in or very near the fields. More stars are seen in all four warp fields compared to the four control directions, and the excesses are unlikely to be caused solely by the sun's position north of midplane. One warp-control field pair appear to have very similar reddening versus distance behavior, and simple subtraction of the control field from the warp field reveals a well-defined main sequence and perhaps a turnoff for the outer stellar disk. In the absence of detailed reddening and metallicity estimates, we cannot yet estimate the distances and ages of the outer disk stars.