Investigation of blue-sensitive photographs of HDE 226868 = Cygnus X-1 reveal no (+ or - 0.06 mag) long-term changes in brightness since the beginning of the century nor any abrupt intensity changes similar to what was observed at X-ray and radio frequencies. From the double sinusoidal fluctuation with 5.6 day period, an attempt is made to derive a more precise value for the orbital period, but problems are encountered and discussed. There exists evidence that the amplitude of the orbital fluctuations is increasing slowly with time.


    Access

    Access via TIB

    Check availability in my library


    Export, share and cite



    Title :

    The long term variability of HDE 226868 = Cygnus X-1


    Contributors:
    Liller, W. (author)


    Publication date :

    1976-01-01


    Type of media :

    Conference paper


    Type of material :

    No indication


    Language :

    English


    Keywords :



    Cygnus X-1 from RXTE: Monitoring the Short Term Variability

    Pottschmidt, K. / Wilms, J. / Staubert, R. et al. | British Library Conference Proceedings | 2001


    Cygnus X-1 from RXTE: monitoring the short term variability

    Pottschmidt, K. | Online Contents | 2001


    The time variability of Cygnus X-1

    Weisskopf, M. C. | NTRS | 1976


    The Long-Term Hard X-Ray Behavior of Cygnus X-1

    Paciesas, W. S. / Pendleton, G. N. / Harmon, B. A. et al. | NTRS | 1994