Abstract
The Transition Region and Coronal Explorer (TRACE) instrument includes a “white light” imaging capability with novel characteristics. Many flares with such white-light emission have been detected, and this paper provides an introductory overview of these data. These observations have 0.5″ pixel size and use the full broad-band response of the CCD sensor; the images are not compromised by ground-based seeing and have excellent pointing stability as well as high time resolution. The spectral response of the TRACE white-light passband extends into the UV, so these data capture, for the first time in images, the main radiative energy of a flare. This initial survey is based on a sample of flares observed at high time resolution for which the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) had complete data coverage, a total of 11 events up to the end of 2004. We characterize these events in terms of source morphology and contrast against the photosphere. We confirm the strong association of the TRACE white-light emissions - which include UV as well as visual wavelengths – with hard X-ray sources observed by RHESSI. The images show fine structure at the TRACE resolution limit, and often show this fine structure to be extended over large areas rather than just in simple footpoint sources. The white-light emission shows strong intermittency both in space and in time and commonly contains features unresolved at the TRACE resolution. We detect white-light continuum emission in flares as weak as GOES C1.6. limited by photon statistics and background solar fluctuations, and support the conclusion of Neidig (1989) that white-light continuum occurs in essentially all flares.
Similar content being viewed by others
References
Carrington, R. C.: 1859, MNRAS 20, 13.
Chapman, S. and Bartels, J.: 1940, Geomagnetism. Oxford: University Press.
Gurzadian, G. A.: 1980, Flare Stars. International Series in Natural Philosophy, Oxford: Pergamon Press.
Handy, B. N., Acton, L. W., Kankelborg, C. C., Wolfson, C. J., Akin, D. J., Bruner M. E. et al.: 1999, Solar Phys. 187. 229.
Hudson, H. S.: 1972, Solar Phys. 24, 414.
Hudson, H. S., Acton, L. W., Hirayama, T., and Uchida, Y.: 1992, Publ. Astron. Soc. Japan 44, L77.
Leibacher, J. W., Harvey, J. W., Kopp, G., Hudson, H., and GONG Team: 2004, American Astronomical Society Meeting Abstracts 204.
Lin, R. P., Dennis, B. R., Hurford, G. J., Smith, D. M., Zehnder, A., Harvey P. R. et al.: 2002, Solar Phys. 210, 3.
Machado, M. E., Emslie, A. G. and Avrett, E. H.: 1989, Solar Phys. 124, 303.
Matthews, S. A., van Driel-Gesztelyi, L., Hudson, H. S., and Nitta, N. V.: 2003, Astron. Astrophys. 409, 1107.
Metcalf, T. R., Alexander, D., Hudson, H. S., and Longcope, D. W.: 2003, Astrophys. J. 595, 483.
Neidig, D. F.: 1989, Solar Phys. 121, 261.
Neidig, D. F. and Cliver, E. W.: 1983, NASA STI/Recon Technical Report N 84, 24521.
Neidig, D. F. and Kane, S. R.: 1993, Solar Phys. 143, 201.
Neidig, D. F., Kiplinger, A. L., Cohl, H. S., and Wiborg, P. H.: 1993, Astrophys. J. 406, 306.
Neidig, D. F., Wiborg, P. H., and Gilliam, L. B.: 1993, Solar Phys. 144, 169.
Rust, D. M. and Hegwer, F.: 1975, Solar Phys. 40, 141.
Švestka, Z.: 1970, Solar Phys. 13, 471.
Švestka, Z.: 1976, Solar Flares, Dordrecht: Reidel.
Xu, Y., Cao, W., Liu, C., Yang, G., Qiu, J., Jing, J., Denker, C., and Wang, H.: 2004, Astrophys. J. (Lett.) 607, L131.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Hudson, H.S., Wolfson, C.J. & Metcalf, T.R. White-Light Flares: A TRACE/RHESSI Overview. Sol Phys 234, 79–93 (2006). https://doi.org/10.1007/s11207-006-0056-y
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s11207-006-0056-y