Today at the 219th meeting of the American Astronomical Society, SDSS-III astronomers presented new evidence probing the history of the disk of our galaxy from SEGUE-2 and the first peak at science from impressive new APOGEE instrument.
For more details see the press releases at:
which include the following figures highlighting the results:
The agove figure shows the “first-light” field of stars observed by APOGEE. This field is filled with Milky Way stars, star clusters and dust (seen as colored, glowing clouds in this image from NASA’s WISE infrared observatory). The large white circle is the field of view of APOGEE, with a width spanning six moon diameters. The green circles indicate known or suspected young star clusters. The small red circles indicate the position of each faint star targeted with APOGEE’s fiber optic system. The inset shows pieces of the APOGEE spectra for stars determined by APOGEE to be members of two of the clusters shown. These members were identified by the near identical motions through the galaxy shared by each clusters’ stars. The motions are detected as shifts of the spectral features caused by the Doppler effect. These dark line features are caused by absorption of specific colors of light by the atoms of the different chemical elements in each star. Figure Credit: P. Frinchaboy (Texas Christian University), J. Holtzman (New Mexico State University), M. Skrutskie (University of Virginia), G. Zasowski (University of Virginia), NASA, JPL-Caltech and the WISE Team.
The above figure highlights the measurements of the metal content of stars in the disk of our Galaxy, using stars observed by SDSS-III’s SEGUE-2 survey. Horizontal lines describe where SEGUE data measure the chemical composition of stars near and above the plane of the disk. The bottom panel shows the decrease in metal content as the distance from the Galactic center increases for stars near the plane of the Milky Way disk. In contrast, the metal content for stars far above the plane, shown in the upper panel, is nearly constant at all distances from the center of the Galaxy. The image of the Milky Way is from the Two-Micron All Sky Survey. Figure Credit: Judy Cheng and Connie Rockosi (University of California, Santa Cruz) and the 2MASS Survey.