Selection of metal-poor giant stars using the sloan digital sky survey photometric system

Amina Helmi, Željko Ivezić, Francisco Prada, Laura Pentericci, Constance M. Rockosi, Donald P. Schneider, Eva K. Grebel, Daniel Harbeck, Robert H. Lupton, James E. Gunn, Gillian R. Knapp, Michael A. Strauss, Jonathan Brinkmann

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


We present a method for the photometric selection of metal-poor halo giants from the imaging data of the Sloan Digital Sky Survey (SDSS). These stars are offset from the stellar locus in the g-r versus u-g color-color diagram. Based on a sample of 29 candidates for which spectra were taken, we derive a selection efficiency of the order of 50% for stars brighter than r ∼ 17 mag. The candidates selected in 400 deg of sky from the SDSS Early Data Release trace the known halo structures (tidal streams from the Sagittarius dwarf galaxy and the Draco dwarf spheroidal galaxy), indicating that such a color-selected sample can be used to study the halo structure even without spectroscopic information. This method, and supplemental techniques for selecting halo stars, such as RR Lyrae stars and other blue horizontal-branch stars, can produce an unprecedented three-dimensional map of the Galactic halo based on the SDSS imaging survey.

Original languageEnglish (US)
Pages (from-to)195-200
Number of pages6
JournalAstrophysical Journal
Issue number1 I
StatePublished - Mar 20 2003
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Galaxy: general
  • Galaxy: halo
  • Galaxy: structure
  • Stars: Population II
  • Surveys
  • Techniques: photometric


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