Flare observation of the Sun as a star by SUMER/SOHO in the hydrogen Lyman continuum
Abstract
During the execution of the programme ``Sun as a star'', while the SUMER (Solar Ultraviolet Emission of Emitted Radiation)/SOHO (SOlar and Heliospheric Observatory) slit was collecting the scattered radiation from the telescope mirror far away from the solar disk image, a class X5.3/3b flare erupted on the solar disk, on 25 August 2001. During the first phase of the flare a relative increase of a few percent was detected at the head of the hydrogen Lyman continuum. After correction from the instrumental parameters, the relative signal increase is 70% at the head of the Lyman continuum (910 Å), and 190% in the C II 904 Å multiplet. Accounting for the area of the flare region, the local increase of the radiance of the Lyman continuum and of the C II lines is estimated to be a factor of several thousands. We compare this result with other solar observations and models.
Appendix A is only available in electronic form at http://www.edpsciences.org- Publication:
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Astronomy and Astrophysics
- Pub Date:
- May 2004
- DOI:
- 10.1051/0004-6361:20034405
- Bibcode:
- 2004A&A...418..737L
- Keywords:
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- Sun: flares;
- Sun: UV radiation;
- stars: flare