Abstract
view Abstract Citations (16) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Photometric Study of Sun-Spots and Faculae Richardson, R. S. Abstract The intensities of sun-spots and faculae at different distances from the center of the sun's disk, relative to the intensity of the surrounding photosphere, have been deter- mined from the direct photographs of the sun taken at Mount Wilson since 1925. The photographs were calibrated by assuming that the intensity across the disk for the effective wave-length of the plate corresponds to that given by Abbot. Direct standard- ization of plates of the same brand by diaphragming the objective shows that on the average they do not differ from Abbot's intensities by more than 4 per cent. The measurements on sun-spots indicate that the ratio of intensity of any part of the spot to that of the surrounding photosphere is independent of the distance from the center of the disk. The observations can be represented better by assuming that sun- spots are in radiative rather than in adiabatic equilibrium. The relation between the intensity and the area of sun-spots was investigated by measuring the intensity of the penumbra in fifteen spot groups. The areas of the indi- vidual spots, corrected for foreshortening, ranged from 78 to 2860 miffionths of the sun's visible hemisphere. The logarithms of the areas plotted against the intensity ratios, penumbra/photosphere, indicate a roughly linear relation. The intensity of the faculae relative to the surrounding photosphere was measured at various points between o.6o-o.95 of the distance from the center of the disk to the limb. Minnaert and Wanders have advanced a theory of the faculae based on the fact that a rising column of gas expanding adiabatically will be brighter than its surround- ings if the ratio of the specific heats is less than 1.33. A fair agreement with the observa- tions can be obtained by assuming a ratio of specific heats equal to i .14 Publication: The Astrophysical Journal Pub Date: December 1933 DOI: 10.1086/143513 Bibcode: 1933ApJ....78..359R full text sources ADS | Related Materials (1) Reprint: 1933CMWCI.480....1R
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
