SPHEREx Releases Catalog of Targets for Ices Studies

News Release • December 6th, 2023
20230616 splicesposter gponly

The spatial distribution of SPLICES targets in Galactic coordinates. Despite the cloud-like appearance of this image, it consists of almost nine million individual dots each indicating the position of an object in the Milky Way or Magellanic Clouds that will be targeted by SPHEREx in its search for ices. Green dots indicate targets expected to lie behind Av > 10 mag of dust extinction, based on their H − W2 colors. Red dots indicate the locations of H-undetected (and therefore likely highly obscured) objects selected on the basis of their red Ks − W2 colors. The dark grey points indicate objects that are undetected in any 2MASS band, which are therefore suspected to be the most highly extincted by dust, on average, of all SPLICES targets. Unsurprisingly, the distribution traces the structure of known Milky Way molecular clouds, and concentrates toward the central ±60° of the Milky Way disk.

Understanding the origin and evolution of molecules of potential biogenic interest [for example, (H2O, CO, CO2) that are incorporated from the interstellar medium into stars and planetary systems as they form is one of the three primary objectives of the SPHEREx mission.  The data to be gathered to study this process will consist of SPHEREx 0.75 to 5 µm spectra of millions of stars throughout the Milky Way Galaxy and the Large Magellanic Clouds.  These stars have been carefully chosen to sample a wide range of interstellar and circumstellar conditions.  Because the interstellar medium is so cold, SPHEREx will detect these molecules in their solid phase, as ices.  The SPHEREx List of ICE Sources (SPLICEs), just published by a team led by CfA astronomers Matthew Ashby and Joseph Hora, presents a catalog of 8.9 million objects of interest for the upcoming SPHEREx Ices investigation.  A large subset of these as well as other targets to be identified before the SPHEREx launch will have their spectra produced by the SPHEREx Science Data System for use by the SPHEREx team and the astronomical community.  The figure above shows the SPLICES objects’ distribution on the sky.  SPLICES 7.3 is now being served by the IRSA archive at the IPAC data center at Caltech, using this link . For further information about SPLICES please look here. We welcome comments and suggestions regarding SPLICES and possible targets of interest which should be added to further improve the scientific return of the SPHEREx Ices Investigation. Interested parties should contact Matthew Ashby at the Center for Astrophysics | Harvard & Smithsonian (mashby@cfa.harvard.edu).

 


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