Research presents new strategy for major astronomical survey

Astronomer of the Universidad de Chile leads a research that presents an object selection strategy for the APOGEE-2 project, a high-resolution, near-infrared, multi-point spectroscopic survey of the Milky Way using data obtained with the du Pont telescope of the Las Campanas Observatory. Also participating in the study were Carnegie Institution for Science researchers Rachael Beaton, Juna A. Kollmeier, Joshua D. Simon, Maria R. Drout, Alycia Weinberger and Johanna Teske. The research was published in the latest issue of The Astronomical Journal.

"The program represents a revolution for astronomy, since until now there had not been a study as complete as this one, especially of the most central areas of the observed object, which are the most difficult to study," says Felipe Santana, postdoctoral researcher at the University of Chile and leader of the research.

Santana adds that APOGEE is the most important catalog of astronomical objects carried out so far. "We obtain information from all these stars to reconstruct how the Milky Way has evolved over billions of years. Our publication tells the strategy used to decide where and why to observe," says the astronomer.

According to the scientist, "APOGEE is a giant project involving hundreds of astronomers from all over the world and has taken several years of work. My greatest collaboration, in this sense, has been to lead a study in which we detail to the astrophysical community how and why we observe the different types of stars analyzed. Without this information it is impossible to interpret the APOGEE results and therefore our work is a key step in the creation of APOGEE," he says.

Detecting and cataloging stars

The APOGEE project consists of the observation of nearly 300,000 stars from all regions of the Milky Way, for which the Sloan 2.5-meter telescopes in the United States and the Irénée du Pont in Chile (located at the Las Campanas Observatory of the Carnegie Institution for Science) were used, where a technique called spectroscopy was used, which consists of taking the light from the stars and separating it into its different wavelengths to see how much light reaches us at each frequency or color.

"We were able to detect how those stars are moving and what their chemical composition is. We also took several observations per star at different times, we were able to study how they are changing in the short term. Work like this serves to dramatically increase the prominence of Chilean institutions in the most important astronomical projects in the world," explains Santana, adding that it is a reflection of the important development that is being done in the area of astronomical instrumentation from the area of engineering. Thanks to this, "Chile could begin to lead more relevant international projects in the area," he says.

Now, the team's objective will be to move on to the development of the fifth generation of their observation methods, which will include new instruments and technologies, while Santana prepares another scientific article detailing the techniques used in the new observations. In this work, together with Santana, participated the researchers Ricardo Muñoz (Uchile-CATA); Julia E. O'Connell (UDEC), Douglas Geisler (Udec-CATA), Amelia M. Stutz (Udec-CATA); Manuela Zoccali (UC-MAS-CATA) and Alvaro Rojas-Arriagada (UC-MAS). Also participating were Rachael L. Beaton from the Department of Astrophysical Sciences at Princeton University and Kevin R. Covey from the Department of Physics and Astronomy at Western Washington University. All of them collaborated in the article "Final Targeting Strategy for the SDSS-IV APOGEE-2S Survey", which was published in the journal "The Astronomical Journal", a free version of which can be viewed at this link.

Source: Departamento de Astronomía de la Universidad de Chile

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