THE SOLAR X-RAY CONTINUUM MEASURED BY RESIK

Journal Article · Mon Mar 01 00:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/711/1/179· OSTI ID:21394387

Phillips, K J. H. ^[1]; Sylwester, J; Sylwester, B ^[2]

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1. Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT (United Kingdom)
2. Space Research Centre, Polish Academy of Sciences, 51-622, Kopernika 11, Wroclaw (Poland)

The solar X-ray continuum emission at five wavelengths between 3.495 A and 4.220 A for 19 flares in a 7-month period in 2002-2003 was observed by the RESIK (REntgenovsky Spektrometr s Izognutymi Kristalami) crystal spectrometer on CORONAS-F. In this wavelength region, free-free and free-bound emissions have comparable fluxes. With a pulse-height analyzer having settings close to optimal, the fluorescence background was removed so that RESIK measured true solar continuum in these bands with an uncertainty in the absolute calibration of +-20%. With an isothermal assumption, and temperature and emission measure derived from the ratio of the two GOES channels, the observed continuum emission normalized to an emission measure of 10{sup 48} cm{sup -3} was compared with theoretical continua using the CHIANTI atomic code. The accuracy of the RESIK measurements allows photospheric and coronal abundance sets, important for the free-bound continuum, to be discriminated. It is found that there is agreement to about 25% of the measured continua with those calculated from CHIANTI assuming coronal abundances in which Mg, Si, and Fe abundances are four times photospheric.

• OSTI ID: 21394387
• Journal Information: Astrophysical Journal, Vol. 711, Issue 1; Other Information: DOI: 10.1088/0004-637X/711/1/179; ISSN 0004-637X
• Country of Publication: United States
• Language: English

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