Abstract
The Transition Region and Coronal Explorer (TRACE) – described in the companion paper by Handy et al. (1999) – provides an unprecedented view of the solar outer atmosphere. In this overview, we discuss the initial impressions gained from, and interpretations of, the first million images taken with TRACE. We address, among other topics, the fine structure of the corona, the larger-scale thermal trends, the evolution of the corona over quiet and active regions, the high incidence of chromospheric material dynamically embedded in the coronal environment, the dynamics and structure of the conductively dominated transition region between chromosphere and corona, loop oscillations and flows, and sunspot coronal loops. With TRACE we observe a corona that is extremely dynamic and full of flows and wave phenomena, in which loops evolve rapidly in temperature, with associated changes in density. This dynamic nature points to a high degree of spatio-temporal variability even under conditions that traditionally have been referred to as quiescent. This variability requires that coronal heating can turn on and off on a time scale of minutes or less along field-line bundles with cross sections at or below the instrumental resolution of 700 km. Loops seen at 171 Å (∼1 MK) appear to meander through the coronal volume, but it is unclear whether this is caused by the evolution of the field or by the weaving of the heating through the coronal volume, shifting around for periods of up to a few tens of minutes and lighting up subsequent field lines. We discuss evidence that the heating occurs predominantly within the first 10 to 20 Mm from the loop footpoints. This causes the inner parts of active-region coronae to have a higher average temperature than the outer domains.
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Aschwanden, M. and Bastian, T.: 1993, Astrophys. J. 426, 434.
Aschwanden, M., Fletcher, L., Schrijver, C. J., and Alexander, D.: 1999, Astrophys. J., in press
Berger, T. E., De Pontieu, B., Schrijver, C. J., and Title, A. M.: 1999, Astrophys. J. 519, L97.
Bray, R. J., Cram, L. E., Durrant, C. J., and Loughhead, R. E.: 1991, Plasma Loops in the Solar Corona, Cambridge University Press, Cambridge.
Brosius, J.W., Davila, J.M., Saba, R. J., Thomasand J. L. R., Hara, H., and Monsignori-Fossi, B. C.: 1997, Astrophys. J. 477, 969.
Canfield, R. C., Zarro, D. M., Wülser, J.-P., and Dennis, B. R.: 1991, Astrophys. J. 367, 671.
Cargill, P. J., Chen, J., and Garren, D. A.: 1994, Astrophys. J. 423, 854.
Craig, I. J. D. and McClymont, A. N.: 1978, Solar Phys. 70, 97.
Delaboudiniere, J.-P., Artzner, G. E., Brunaud, J., Gabriel, A. H., Hochedez, J. F., Millier, F., Song, X. Y., Au, B., Dere, K. P., Howard, R. A., Kreplin, R., Michiels, D. J., Moses, J. D., Defise, J. M., Jamar, C., Rochus, P., Chauvineau, J. P., Marioge, J. P., Catura, R. C., Lemen, J. R., Shing, L., Stern, R. A., Gurman, J. B., Neupert, W. M., Maucherat, A., Clette, F., Cugnon, P., and van Dessel, E. L.: 1995, Solar Phys. 162, 291.
Fletcher, L. and De Pontieu, B.: 1999, Astrophys. J., in press.
Foukal, P. V., Huber, M. C. E., Noyes, R.W., Reeves, E.M., Schmahl, E. J., Timothy, J. G., Vernazza, J. E., and Withbroe, G. L.: 1974, Astrophys. J. 193, L143.
Galsgaard, K. and Nordlund, A.: 1996, J. Geophys. Res. 101, 13445.
Galsgaard, K., Mackay, D. H., Priest, E.R., and Nordlund, A.: 1999, Solar Phys., in press
Golub, L., Herant,M., Kalata, K., Lovas, I., Nystrom, G., Pardo, F., Spiller, E., and Wilczynski, J. S.: 1990, Nature 344, 842.
Handy, B. N., Acton, L. W., Kankelborg, C. C., Wolfson, C. J., Akin, D. J., Bruner, M. E., Carvalho, R., Catura, R. C., Chevalier, R., Duncan, D.W., Edwards, C. G., Feinstein, C. N., Freeland, S. L., Friedlander, F.M., Hoffman, C. H., Hurlburt, N. E., Jurcevich, B. K., Katz, N. L., Kelly, G. A., Lemen, J. R., Levay, M., Lindgren, R.W., Mathur, D. P., Meyer, S. B., Morrison, S. J., Morrison, M.D., Nightingale, R. W., Pope, T. P., Rehse, R.A., Schrijver, C. J., Shine, R.A., Shing, L., Tarbell, T. D., Title, A. M., Torgerson, D. D., Golub, L., Bookbinder, J. A., Caldwell, D., Cheimets, P. N., Davis, W. N., Deluca, E. E., McMullen, R. A., Amato, D., Fisher, R., Maldonado, H., and Parkinson, C.: 1999, Solar Phys. 187, 229(this issue).
Ichimoto, K., Kumagai, K., Sakurai, T., Hara, H., Takeda, A. et al.: 1994, in S. Enome and T. Hirayama (eds.), Poceedings of Kofu Symposium, NRO report No. 360, Radioheliograph Series 6, Nobeyama, Japan, p. 1131.
Kankelborg, C. C., Walker, A. B. C., and Hoover, R. B.: 1997, Astrophys. J. 491, 952.
Klimchuk, J. A. and Gary, D. E.: 1995, Astrophys. J. 448, 925.
Kucera, T. A., Andretta, V., and Poland, A. I.: 1999, Solar Phys. 183, 107.
Laming, J. M., Drake, J. J., and Widing, K. G.: 1995, Astrophys. J. 443, L416.
Lites, B. W.: 1992, Sunspots: Theory and Observations, NATO Advanced Research Workshop on the Theory of Sunspot, p. 261.
Longcope, D. and Kankelborg, C. C.: 1999, Astrophys. J., in press.
Mariska, J. T.: 1992, The Solar Transition Region, Cambridge University Press, Cambridge.
Nordlund, Å. and Galsgaard, K.: 1997, in G. M. Simnett, C. E. Alissandrakis, and L. Vlahos (eds.), Solar and Heliospheric Plasma Physics, Proceedings of the 8th European Meeting on Solar Physics Held at Halkidiki, near Thessaloniki, Greece, 13–18 May, 1996, Lecture Notes in Physics, Vol. 489, Springer, Heidelberg.
November, L. J. and Koutchmy, S.: 1996, Astrophys. J. 466, 512.
Orlando, S., Peres, G., and Serio, S.: 1995a, Astron. Astrophys. 294, 861.
Orlando, S., Peres, G., and Serio, S.: 1995b, Astron. Astrophys. 300, 549.
Parnell, C. E., Priest, E. R., and Titov, V. S.: 1994, Solar Phys. 153, 217.
Peres, G., Reale, F., and Golub, L.: 1994, Astrophys. J. 422, 412.
Porter, L. J. and Klimchuk, J. A.: 1995, Astrophys. J. 454, 499.
Roberts, B., Edwin, P. M., and Benz, A. O.: 1984, Astrophys. J. 279, 857.
Rosner, R., Tucker, W. H., and Vaiana, G. S.: 1978, Astrophys. J. 220, 643.
Sams, B. J., Golub, L., and Weiss, N. O.: 1992, Astrophys. J. 399, 313.
Schmelz, J. T., Holman, G. D., Brosius, J. W., and Willson, R. F.: 1994, Astrophys. J. 434, 786.
Schrijver, C. J., Lemen, J. R., and Mewe, R.: 1989, Astrophys. J. 341, 484.
Schrijver, C. J., Shine, R. A., Hurlburt, N. E., Tarbell, T. D., and Lemen, J. R.: 1997a, in O. Kjeldseth-Moe and A. Wilson (eds.), Proceedings of the 5th SOHO Workshop, Oslo, June 1997, ESA SP-404, Noordwijk, The Netherlands, p. 669.
Schrijver, C. J., Title, A. M., Van Ballegooijen, A. A., Hagenaar, H. J., and Shine, R. A.: 1997b, Astrophys. J. 487, 424.
Schrijver, C. J., McMullen, R. A., Rutten, R. J., and Kaastra, J. S.: 1999, Astrophys. J., in preparation.
Serio, S., Peres, G., Vaiana, G. S., Golub, L., and Rosner, R.: 1981, Astrophys. J. 243, 288.
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Schrijver, C., Title, A., Berger, T. et al. A new view of the solar outer atmosphere by the Transition Region and Coronal Explorer. Sol Phys 187, 261–302 (1999). https://doi.org/10.1023/A:1005194519642
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DOI: https://doi.org/10.1023/A:1005194519642