Comparison of NIXT and SXT images Grazing incidence or normal incidence for Japan's next mission? 

mi002.yoshida01
Posted:  06-Nov-93
Updated: 08-Oct-94, 20-Nov-94, 3-Feb-95
Events specified: N/A

K. Yoshida, S. Tsuneta Institute of Astronomy, University of Tokyo L. Golub Harvard-Smithonian Center for Astrophysics L. Acton Montana State University

Obsolete Note as of Nov-93. abandoned Oct-94: This project does not aim for the scientific paper publication.

This is an undergraduate research program of U. Tokyo for Yoshida, and the final report should be written by him by end February.

Purpose: We would like to make scientific assessment on whether grazing incidence optics or/and normal incidence topics should be used for Japan's next solar mission. The research should include the following topics:

    1. Detailed morphological comparison of coronal structure 

           Particular emphasis is put on the identification of the
     footpoints of the coronal loops.
      
    2.  Estimation of the temperature of the coronal structure     
      
    3.  Assessment on grazing incidence optics and normal incidence
    optics for the next mission. Also, we would like to compare these images with Prof. Walker's images taken in many different lines, although this is not a simultaneous observations.

    Update 3-Feb-95

    We would like to ssuccessfully close this project by the publication of the following paper:

    Temperature Structure of the Solar Corona: Comparison of NIXT and Yohkoh X-ray images by Yoshida, Tsuneta, Golub, Strong, Ogawara In press (PASJ).

    The abstract is in the update of 20-Nov-94.

    Update 20-Nov-94

    The following paper was submitted to PASJ:

    Temperature Structure of the Solar Corona: Comparison of NIXT and Yohkoh X-ray images

    Tsuyoshi Yoshida, Saku Tsuneta Institute of Astronomy, The University of Tokyo, Mitaka, Tokyo 181

    Leon Golub Smithonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138

    Keith Strong Lockheed Solar and Astrophysics Laboratory, 3251 Hanover Street, Palo Alto, CA 94304

    Yoshiaki Ogawara Institute of Space and Astronautical Science, Sagamihara, Kanagawa 229

    Abstract Solar soft X-ray images simultaneously taken by the {\it Yohkoh} and the normal incidence X-ray telescope (NIXT) reveal significantly different coronal structures. Coronal loops are more clearly seen in the {\it Yohkoh} images, and the island-like structures seen in the NIXT image are found to correspond to the footpoints of the {\it Yohkoh} loops. The difference is due to the difference in the temperature response of the telescopes: NIXT is sensitive to temperature range from 0.9 MK through 3 MK, while {\it Yohkoh} is sensitive to temperatures above 2.5 MK. The significant difference reflects multi-temperature (1 MK -- 5MK) nature of the solar coronal plasmas.

    Update 08-Oct-94

    Althoug the initial purpose of this project was for Solar-B, we are now completing the science paper fro PASJ letters. The abstract of the paper is as follows:

    Temperature Structure of the Solar Corona: Comparison of NIXT and Yohkoh images

    Tsuyoshi Yoshida, Saku Tsuneta Leon Golub Keith Strong Yoshiaki Ogawara

    To be submitted to the Publications of the Astronomical Society of Japan (Letters)

    Abstract Solar X-ray images simultaneously taken by the {\it Yohkoh} and the normal incidence X-ray telescope (NIXT) reveal significantly different coronal structures. Coronal loops are more clearly seen in the {\it Yohkoh} images, and the island-like structures seen in the NIXT image are found to correspond to the footpoints of the {\it Yohkoh} loops. We demonstrate that this difference is due to the difference of the temperature response of the telescopes. NIXT is sensitive to temperature range from 1 MK through 3 MK, while {\it Yohkoh} is sensitive to temperatures above 3 MK. The present observation clearly show the multi-temperature nature of the solar coronal plasmas.