Sloan Digital Sky Survey | 2017 Mar 29
[img3="The “first light” observations for the APOGEE South spectrograph. The dots show stars whose spectra were observed by APOGEE. Some example spectra are shown (colors are representative only, as APOGEE spectra are in the infrared).Earlier this month, the Sloan Digital Sky Survey (SDSS) reached an important milestone by opening its “second eye on the sky” – a new instrument called the “APOGEE South spectrograph.”
The first light observations included spectra of supermassive stars in the Tarantula Nebula. This nebula in the Large Magellanic Cloud is forming stars more rapidly than any other region in our Local Group of galaxies. It can only be seen from the Southern Hemisphere, underscoring the importance of APOGEE South’s location. The spectrograph will allow us to study the chemistry and evolution of the stars in the nebula in greater detail than ever before.
Image Credit: SDSS collaboration; Tarantula Nebula image from Herschel/Spitzer"]http://www.sdss.org/press-releases/wp-c ... ght_sm.png[/img3][hr][/hr]
This new instrument at Las Campanas Observatory in Chile is the twin of the APOGEE North spectrograph, and will let astronomers study stars across the whole Milky Way like never before.
The name APOGEE is short for the Apache Point Observatory Galaxy Evolution Experiment, based on the location of the experiment’s first “eye” at Apache Point Observatory, New Mexico. “The original APOGEE made history by measuring extremely detailed properties of more stars than ever before,” said Steven Majewski of the University of Virginia, Principal Investigator of the APOGEE experiment. “But we always wanted a more complete view, especially because the center of the Galaxy is best seen from the Southern Hemisphere. With the APOGEE South spectrograph, we are finally realizing that vision.” Data collected by the twin instruments will help astronomers make a map of the entire Milky Way, with an unprecedented combination of size and detail.
The APOGEE South spectrograph in Chile is identical to the original APOGEE spectrograph in New Mexico. Both work by spreading starlight into detailed rainbow patterns called “spectra.” Astronomers use these spectra to determine the chemical compositions of those stars, and also to find subtle shifts due to the Doppler effect created by the stars’ motion through space. These pieces of information -- composition and velocity -- are combined with the known stellar positions to create an incredibly detailed map of our galaxy. ...
