Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

An early-medieval account on the red colour of Sirius and its astrophysical implications


An unresolved problem regarding ancient astronomical records is that of the star ‘Red Sirius’. While Sirius today shines white with a blueish hue quite in agreement with its spectral type AIV, many Greek/Roman and Babylonian sources (although still disputed) definitely assign a red colour to this star. We now present new and apparently independent information about Red Sirius from an early-medieval manuscript. This manuscript is of Lombardic origin (8th century) and contains the otherwise lost ‘De cursu stellarum ratio’ by Gregory of Tours (about AD 538–593). It is preserved in the library of Bamberg1. Red stars in ancient records are those with colour index B−V = 1.0 or greater. Assuming an unchanged Sirius A, this lower limit for the combined colour of Sirius A and B allows the computation of the region of pre-white dwarf Sirius B in the Hertzsprung–Russell diagram or colour–magnitude diagram (Figs 1, 2). Sirius B lies on the giant branch, which fits well with our observational and theoretical framework of stellar evolution. However, the timescale of transformation of a red giant to a white dwarf is surprisingly short.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1

    Bamberg Library Manuscript Identification Code:, H.I., IV, 15 (s.VIII), f. 79–82′.

  2. 2

    Gundel, W. in Realencyclopädie der Classischen Altertumswissenschaften Vol. II.5 (eds Pauly, A. & Wissowa, G.) cols 314–351 (Druckenmüller, Stuttgart, 1927).

    Google Scholar 

  3. 3

    Gössmann, F. Planetarium Babylonicum (Scripta Pontificii Instituti Biblici, Rome 1950).

    Google Scholar 

  4. 4

    Brecher, K. & Feirtag, M. (eds) Astronomy of the Ancients, 91–115 (MIT Press, Cambridge, 1979).

  5. 5

    Hoffleit, D. Bright Star Catalogue (Yale University Observatory, New Haven, 1982).

    Google Scholar 

  6. 6

    Allen, C. W. Astrophysical Quantities 3rd Edn, 144 (University of London, 1973).

    Google Scholar 

  7. 7

    Houk, N. & Fesen, R. IAU Symp. 80, 91 (1978).

    ADS  Google Scholar 

  8. 8

    Ciardullo, R. B. & Demarque, P. Dudley Obs. Rep. 14, 317 (1979).

    ADS  CAS  Google Scholar 

  9. 9

    Schmidt-Kaler, Th. in Landolt-Börnstein Vol. 2b (eds Schaifers, K. & Voigt, H. H.) 1 (Sprittgef, Berlin, 1982).

    Google Scholar 

Download references

Author information



Rights and permissions

Reprints and Permissions

About this article

Cite this article

Schlosser, W., Bergmann, W. An early-medieval account on the red colour of Sirius and its astrophysical implications. Nature 318, 45–46 (1985).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing