TODCOR - Two-dimensional correlation

Shay Zucker*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


TODCOR is a TwO-Dimensional CORrelation technique to measure radial velocities of the two components of a spectroscopic binary. Assuming the spectra of the two components are known, the technique correlates an observed binary spectrum against a combination of the two spectra with different shifts. TODCOR measures simultaneously the radial velocities of the two stars by finding the maximum correlation. The main use of the technique has been to turn single-lined binaries into double-lined systems. This helps to explore the binary mass-ratio distribution, especially the low-mass regime, where the secondaries are usually very faint and therefore hard to detect. The technique has been generalized to study multi-order spectra, and also triple- and quadruple-lined systems. It has several applications in studying extrasolar planets and in the future may even help to dynamically measure stellar masses of binaries through relativistc effects.

Original languageEnglish
Title of host publicationFrom Interacting Binaries to Exoplanets
Subtitle of host publicationEssential Modeling Tools
EditorsMercedes Richards, Ivan Hubeny
Number of pages8
StatePublished - Jul 2011

Publication series

NameProceedings of the International Astronomical Union
ISSN (Print)1743-9213
ISSN (Electronic)1743-9221


  • Celestial mechanics
  • binaries: spectroscopic
  • brown dwarfs
  • methods: data analysis
  • planetary systems
  • stars: low mass
  • techniques: radial velocities
  • techniques: spectroscopic


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