Abstract
Two thirds of the Hα flares associated in time and position with coronal mass ejections (CME) observed by the Coronagraph/Polarimeter (C/P) or by the coronagraph on Skylab lie within 30° of the solar limb. Among type II flares (those with type II radio spectral bursts) with C/P observations, 10 are within 10° of the limb and 8 of these are associated with CME. The high rate of CME association at the limb is interpreted here to imply: (1) Most type II flares (at least 80%) are physically associated with mass motion in the corona (although about half of CME flares lack type II bursts). (2) The longitude window, centered on the plane of the sky, within which C/P and Skylab coronagraphs detect CME has halfwidth of 20° to 30°. (3) CME observed at polar position angles are unlikely to be flare associated. (4) The total number of mass ejections must be considerably greater than the number detected. The ratio of total number to observed number is estimated to be between 2 and 3, and the total occurrence frequency of coronal mass ejections at solar-cycle maximum to be comparable to that of flares of importance 1. The clear dependence of CME detection on flare position implies that the location of the mass ejection must be well described by the location of the associated flare, and that the ejected mass must have limited longitudinal extent in the corona, comparable to the width of the detection window and to the directly observed latitudinal extent of ∼35° +- 15° for CME observed by C/P and the Skylab coronagraph.
Similar content being viewed by others
References
Csoeke-Poeckh, A., Lee, R. H., Wagner, W. J., House, L. L., Hildner, E., and Sawyer, C.: 1982, J. Spacecraft and Rockets 19, 345.
Dodge, J. C.: 1975, Solar Phys. 42, 445.
Gosling, J. T., Hildner, E., MacQueen, R. M., Munro, R. H., Poland, A. I., and Ross, C. L.: 1976, Solar Phys. 48, 389.
Howard, R. A., Michels, D., Sheeley, N. R. Jr., and Koomen, M.: 1982, Astrophys. J. 263, L101.
Hundhausen, A., Sawyer, C., House, L., Illing, R. and Wagner, W. J.: 1984, J. Geophys. Res. 89, 2639.
Kahler, S., Sheeley, N. R. Jr., Howard, R. A., Koomen, M. R., and Michels, D. J.: 1984, Solar Phys. 93, 133.
Maxwell, A. and Thompson, A. R.: 1962, Astrophys. J. 135, 138.
Munro, R., Gosling, J. T., Hildner, E., MacQueen, R. M., Poland, A. I., and Ross, C. L.: 1979, Solar Phys. 61, 201.
Roberts, J. A.: 1959, Australian J. Phys. 12, 328.
Sawyer, C.: 1985, submitted to J. Geophys. Res.
Sawyer, C., Howard, R., Sheeley, N., Koomen, M., and Michels, D.: 1983, Bull. Am. Astron. Soc. 15, 106.
Sheeley, N., Stewart, R. T., Robinson, R. D., Howard, R. A., Koomen, M. J., and Michels, D. J.: 1984, Astrophys. J. 279, 839.
Stewart, R. T., Dulk, G. A., Sheridan, K. V., House, L. L., Wagner, W. J., Sawyer, C., and Illing, R.: 1982, Astron. Astrophys. 116, 217.
Švestka, Z. and Fritzová-Švestková, L.: 1974, Solar Phys. 36, 417.
Tousey, R., Howard, R. A., and Koomen, M. J.: Bull. Am. Astron. Soc. 6, 295.
van de Hulst, H. C.: 1950, Bull. Astron. Inst. Neth. 11, 135.
Wright, C. S.: 1980, Proc. Astron. Soc. Australia 4, 59.
Author information
Authors and Affiliations
Additional information
Much of the work reported here was done at the High Altitude Observatory, National Center for Atmospheric Research, Boulder, CO 80307, U.S.A. The National Center for Atmospheric Research is sponsored by the National Science Foundation.
Rights and permissions
About this article
Cite this article
Sawyer, C. Visibility and rate of coronal mass ejections. Sol Phys 98, 369–378 (1985). https://doi.org/10.1007/BF00152466
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00152466