The second stage of the Apache Point Observatory Galaxy Evolution Experiment (APOGEE-2) employs the “archaeological” record embedded in hundreds of thousands constituent stars to explore the assembly and formation history of the Milky Way. In essence, the details as to how the Galaxy evolved are preserved today in the motions of its stars as well as in their chemical compositions. APOGEE-2 maps the dynamical and chemical behaviors of Milky Way stars with the use of observations from the 2.5-meter Sloan Foundation Telescope at the Apache Point Observatory in New Mexico (APOGEE-2N), and the 2.5-meter du Pont Telescope at Las Campanas Observatory in Chile (APOGEE-2S). Together with the NASA planet-finding missions Kepler and Kepler-2, APOGEE-2 measures also the abundances of carbon, oxygen, nitrogen and iron in planet-hosting stars, and subsequently, studies the role that these elements play in the formation of planets.
Key Science Questions
- What is the history of star formation and chemical enrichment of the Milky Way?
- What are the dynamics of the disk, bulge and halo of the Milky Way?
- What is the age distribution of stars in the Milky Way?
- Do planet-hosting stars have different and/or unique properties as opposed to stars that have no planets?
To answer the above science questions, APOGEE-2 relies upon stellar spectra taken at near-infrared wavelengths, which can penetrate regions obscured by dust. The APOGEE-2 near-infrared spectral data generate a comprehensive view as to (1) the distributions of element abundances in Galactic stars, and (2) the dynamical motions of stars at various locations throughout the Milky Way. A primer as to the utility of spectra and near-infared spectral observations as well as a background of the Milky Way Galaxy can be found here.
APOGEE-2 Technical Details
- Bright-time observations at APO and LCO
- Fall 2014 – Fall 2020
- 300 fibers per 7 deg² plate (APO), 3.5 deg² plate (LCO)
- Wavelength Range: 1.51-1.70 μm
- Spectral Resolution: R~22,500
- Sample Size: 300,000 stars with signal-to-noise S/N > 100
- Radial Velocity Precision: ~ 200 m/s
- Element Abundance Precision: ~ 0.1 dex for 25 species
- Principal Investigator
- Steve Majewski (UVa)
- Survey Scientist
- Jon Holtzman (NMSU)
- Project Manager
- Fred Hearty (Penn State University)
- Deputy Project Manager
- Jennifer Sobeck (UVa)
- Instrument Scientist
- John Wilson (UVa)
- LCO Operations Manager
- Christian Nitschelm (Universidad de Antofagasta)
- Pipeline Coordinator
- Matt Shetrone (McDonald Observatory)
- Northern Survey Operations Scientist
- Nathan DeLee (Vanderbilt University)
- Southern Survey Operations Scientist