The contrast of magnetic elements in synthetic CH- and CN-band images of solar magnetoconvection

Document Type

Article

Publication Date

3-1-2006

Abstract

We present a comparative study of the intensity contrast in synthetic CH-band and violet CN-band filtergrams computed from a high-resolution simulation of solar magnetoconvection. The underlying simulation has an average vertical magnetic field of 250 G with kilogauss fields concentrated in its intergranular lanes and is representative of a plage region. To simulate filtergrams typically obtained in CH- and CN-band observations we computed spatially resolved spectra in both bands and integrated these spectra over 1 nm FWHM filter functions centered at 430.5 and 388.3 nm, respectively. We find that the average contrast of magnetic bright points in the simulated filtergrams is lower in the CN band by a factor of 0.96. In comparison, earlier semiempirical modeling and recent observations both estimated that the bright point contrast in the CN band is higher by a factor of 1.4. We argue that the near equality of the bright point contrast in the two bands in the present simulation is a natural consequence of the mechanism that causes magnetic flux elements to be particularly bright in the CN and CH filtergrams, namely, the partial evacuation of these elements and the concomitant weakening of molecular spectral lines in the filter passbands. We find that the rms intensity contrast in the whole field of view of the filtergrams is 20.5% in the G band and 22.0% in the CN band and conclude that this slight difference in contrast is caused by the shorter wavelength of the latter. Both the bright point and rms intensity contrast in the CN band are sensitive to the precise choice of the central wavelength of the filter. © 2006. The American Astronomical Society. All rights reserved.

Identifier

33645003708 (Scopus)

Publication Title

Astrophysical Journal

External Full Text Location

https://doi.org/10.1086/499331

e-ISSN

15384357

ISSN

0004637X

First Page

525

Last Page

533

Issue

1 I

Volume

639

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