Hostname: page-component-586b7cd67f-r5fsc Total loading time: 0 Render date: 2024-11-26T05:49:48.009Z Has data issue: false hasContentIssue false

A Spectroscopic Study of the Solar Corona from Norikura and SOHO data

Published online by Cambridge University Press:  13 May 2016

K. P. Raju
Affiliation:
Indian Institute of Astrophysics, Koramangala, Bangalore-560 034, India
T. Sakurai
Affiliation:
National Astronomical Observatory of Japan, 2-21-1, Ohsawa, Mitaka, Tokyo-181, Japan
K. Ichimoto
Affiliation:
National Astronomical Observatory of Japan, 2-21-1, Ohsawa, Mitaka, Tokyo-181, Japan

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

We report the results from a spectroscopic study of the solar corona using both ground-based and space-based data. Some of the current topics in coronal physics, such as the plume-interplume differences in coronal holes and wave propagation in the corona have been examined. The distribution of emission line intensities, Doppler velocities and line widths were obtained from the spectroscopic observations from Norikura Solar Observatory of National Astronomical Observatory of Japan. The coronal images in Fe IX,X 171 Å and Fe XII 195 Å from SOHO EIT were used to get the temperature map of the corona. Combining both results, we have obtained the nonthermal velocities in the coronal hole region, without the usual assumption of a uniform ion temperature. It has been found that the histogram distributions of Doppler velocities and nonthermal velocities for coronal hole and quiet regions are markedly different. The nonthermal velocities have been found to be larger by about 27 %at the interplume regions as compared to plumes which supports the view that the interplume regions are the source regions of the fast solar wind. The analysis of the time sequence spectral data shows signatures of coronal oscillations at localized regions. Periods of the order of a few minutes have been found mainly in Doppler velocities.

Type
Session V: Coronal Heating and Solar Wind Acceleration
Copyright
Copyright © Astronomical Society of the Pacific 2001 

References

Brynildsen, N., Kjeldseth-Moe, K., Maltby, P., & Wilhelm, K. 1999, ApJ, 517, L159.Google Scholar
Domingo, V., Fleck, B. & Poland, A.I., 1995, Sol. Phys., 162, 1.Google Scholar
Fludra, A., 1999, A&A, 344, L75.Google Scholar
Hassler, D.M., Wilhelm, K., Lemaire, P., Schuhle, U. 1997, Sol. Phys., 175, 375.CrossRefGoogle Scholar
Ichimoto, K., Hara, H., Takeda, A., Kumagai, K., Sakurai, T., Shimizu, T., & Hudson, H.S. 1995, ApJ, 445, 978.Google Scholar
Krieger, A.S., Timothy, A.F., & Roelof, E.C. 1973, Sol. Phys., 49, 43.Google Scholar
Ofman, L., Nakariakov, V.M., & DeForest, C.E., 1999, ApJ, 514, 441.Google Scholar
Raju, K.P., Sakurai, T., Ichimoto, K., & Singh, J. 2000, ApJ, in press.Google Scholar
Singh, J., Ichimoto, K., Imai, H., Sakurai, T., & Takeda, A. 1999, PASJ, 51, 269.Google Scholar
Tsubaki, T., 1987, Proceedings of 9th Sac Peak Workshop, Altrock, (ed), p.140.Google Scholar
Wilhelm, K., Marsch, E., Dwivedi, B.N., Hassler, D.M., Lemaire, P., Gabriel, A.H., & Huber, C.E.M., 1998, ApJ, 500, 1023.Google Scholar