Brightness of the solar F-corona
نویسندگان
چکیده
We discuss our present knowledge about the brightness of the solar F-corona in the wavelength range from the visible to the middle infrared. From the general trend of the observational data, the F-corona is regarded as the continuous extension of the zodiacal light at smaller elongation of the line of sight. A contribution of thermal emission from dust is indicated by the increasing F-coronal brightness in comparison to the solar spectrum towards longer wavelength. As compared with the F-coronal brightness, the polarization and color in the visible regime are not well determined due to the high sensitivity of these quantities to the observational accuracy. Aside from observational problems, our present interpretation of the F-coronal brightness is also limited due to ambiguities in the inversion of the line of sight integral. Nevertheless, the measurements and model calculations of the brightness can be used to deduce some physical properties of dust grains. We show that the hump of the near-infrared brightness at 4 solar radii, which was sometimes observed in the corona, is related rather to the physical properties of dust grains along the line of sight than to the existence of a dust ring as previously discussed. We also show that the appearance or disappearance of the near-infrared peak in the coronal brightness cannot be described in any periodic cycle for each wavelength range.
منابع مشابه
بررسی تغییرات شدت در تاج خورشید طی خورشیدگرفتگی 20 مرداد 1378
An experiment to search for short-period intensity oscillations in the solar corona was conducted during the total solar eclipse of August 11, 1999 in Esfahan, Iran. The intensity in the continuum, centered about 4700 Å and with a passband having a half-width of 190 Å, was recorded at a counting rate of 5 Hz using six low-noise Hamamatsu R647 photomultiplier tubes. We recorded intensity value...
متن کاملThe Depiction of Coronal Structure in White Light Images
The very sharp decrease of density with heliocentric distance makes imaging of coronal density structures out to a few solar radii challenging. The radial gradient in brightness can be reduced using numerous image processing techniques, thus quantitative data are manipulated to provide qualitative images. Introduced in this study is a new normalizing radial graded filter (NRGF), a simple filter...
متن کاملCoronal streamers revealed during solar eclipses: Seeing is not believing, and pictures can lie
For those fortunate enough to have personally witnessed and photographed the visible corona surrounding the Sun during a solar eclipse, pictures are usually a let down for not living up to the visual view. After 150 years of investigating the corona, we understand it more fully and now know this difference to be real. The difference stems from our inability to either see or image the true distr...
متن کاملCoronal Magnetic Field Measurements through Gyroresonance Emission
This article reviews the use of gyroresonance emission at radio wavelengths to measure coronal magnetic fields. The spiralling motion of electrons in the 200– 2000 G fields in the solar corona produces sufficient opacity to render the corona optically thick, making it easy to recognize such sources in microwave images from their coronal brightness temperatures. Where gyroresonance sources are p...
متن کاملMapping the Structure of the Corona Using Fourier Backprojection Tomography
Estimating the structure, or density distribution, of the solar corona from a set of 2D white light images made by coronagraphs is a critical challenge in coronal physics. This work describes new data analysis procedures which are used to create global maps of the coronal structure at heights where the corona becomes approximately radial (≥3R ). The technique, which is named Qualitative Solar R...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 1999