The scatter in the near-infrared colour-magnitude relation in spiral galaxies

R. F. Peletier*, R. de Grijs

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


We have determined a dust-free colour-magnitude (CM) relation for spiral galaxies, by using I - K colours in edge-on galaxies above the plane. We find that the scatter in this relation is small and approximately as large as can be explained by observational uncertainties. The slope of the near-IR CM relation is steeper for spirals than for elliptical galaxies. We suggest two possible explanations. First, the difference could be caused by vertical colour gradients in spiral galaxies. In that case these gradients should be similar for all galaxies, on average ∼0.15 dex in [Fe/H] per scaleheight, and should increase for later galaxy types. The most likely explanation, however, is that spirals and ellipticals have intrinsically different CM relations. This means that the stars in spirals are younger than those in ellipticals. The age, however, or the fraction of young stars in spiral galaxies would be determined solely by the luminosity of the galaxy, and not by its environment.

Original languageEnglish
Pages (from-to)L3-L6
Number of pages4
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - 11 Oct 1998
Externally publishedYes


  • galaxies: fundamental parameters
  • galaxies: photometry
  • galaxies: structure


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