30+ frequencies for the δ Scuti variable 4 Canum Venaticorum: Results of the 1996 multisite campaign

M. Breger, G. Handler, R. Garrido, N. Audard, W. Zima, M. Paparó, F. Beichbuchner, Zhi Ping Li, Shi Yang Jiang, Zong Li Liu, Ai Ying Zhou, H. Pikall, A. Stankov, J. A. Guzik, M. Sperl, J. Krzesinski, W. Ogloza, G. Pajdosz, S. Zola, T. ThomassenJ. E. Solheim, E. Serkowitsch, P. Reegen, T. Rumpf, A. Schmalwieser, M. H. Montgomery

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Abstract

The evolved δ Scuti variable 4 CVn was observed photometrically for 53 nights on three continents. We found a total of 34 significant and 1 probable simultaneously excited frequencies. Of these, 16 can be identified as linear combinations of other frequencies. All significant frequencies outside the 4.5 to 10 cd-1 (52 to 116 μHz) range can be identified with frequency combinations, fi ±fi, of other modes with generally high amplitudes. There exists a number of closely spaced frequencies with separations of ∼ 0.06 cd-1. This cannot be explained in terms of amplitude variability. The results show that even for stars on and above the main sequence other than the Sun, a very large number of simultaneously excited nonradial oscillations can be detected by conventional means. Since all pulsation modes with photometric amplitudes of 1 mmag or larger have now been detected for this star, a presently unknown mode selection mechanism must exist to select between the 1000+ of low-degree modes predicted to be excited for this (and many other) stars. Phase differences and amplitude ratios between the y and ν colors are determined for the ten main modes. The phase differences indicate p1 to p4 modes of ℓ = 1 for four of these modes. The formulae to determine the uncertainties in the amplitudes and phases of sinusoidal fits to observational data are derived in the Appendix.

Original languageEnglish
Pages (from-to)225-235
Number of pages11
JournalAstronomy and Astrophysics
Volume349
Issue number1
Publication statusPublished - dec. 1 1999

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ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Breger, M., Handler, G., Garrido, R., Audard, N., Zima, W., Paparó, M., Beichbuchner, F., Li, Z. P., Jiang, S. Y., Liu, Z. L., Zhou, A. Y., Pikall, H., Stankov, A., Guzik, J. A., Sperl, M., Krzesinski, J., Ogloza, W., Pajdosz, G., Zola, S., ... Montgomery, M. H. (1999). 30+ frequencies for the δ Scuti variable 4 Canum Venaticorum: Results of the 1996 multisite campaign. Astronomy and Astrophysics, 349(1), 225-235.