Astronomy and Astrophysics – Astrophysics
Scientific paper
Dec 2008
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008agufmsh13a1503b&link_type=abstract
American Geophysical Union, Fall Meeting 2008, abstract #SH13A-1503
Astronomy and Astrophysics
Astrophysics
7500 Solar Physics, Astrophysics, And Astronomy, 7529 Photosphere, 7536 Solar Activity Cycle (2162)
Scientific paper
The Mount Wilson solar photographic archive digitization project makes available to the scientific community in digital form a selection of the solar images in the archives of the Carnegie Observatories. This archive contains over 150,000 images of the Sun which were acquired over a time span in excess of 100 years. The images include broad-band images called White Light Directs, ionized CaK line spectroheliograms and Hydrogen Balmer alpha spectroheliograms. This project will digitize essentially all of the CaK and broad-band direct images out of the archive with 12 bits of significant precision and up to 3000 by 3000 spatial pixels. This project has already completed the digitization of essentially all of the CaK and about 50% of the broad-band direct images out of the archive with 12 bits of significant precision and up to 3000 by 3000 spatial pixels. Solar images have been extracted and identified with original logbook parameters of observation time and scan format, and they are available from the project web site at www.astro.ucla.edu/~ulrich/MW_SPADP. The rate of solar rotation over the whole solar surface can be determined as a function of time using the day-to day motions of features on these CaK images. We present here preliminary results for the period 1915 to 1975. The pattern of rotation rate is determined by cross-correlating observations taken on successive days for 11 separate latitude zones spanning the solar disk between +/- 50 degrees in latitude. We found that the average rotation rate of the Sun during the 20th century was higher during periods of minimum activity than it was during periods of maximum activity. The difference in the rotation rate at the equator can be estimated at about 0.01 microrad/s. We also found that the orthogonalized rotation coefficients calculated from the northern and southern hemispheres separately show an asymmetry between the two hemispheres, with the northern hemisphere rotating slightly faster than the southern hemisphere.
Bertello Luca
Boyden John E.
Javaraiah J.
Ulrich Richard K.
No associations
LandOfFree
The Solar Rotation Rate Profile from 1915 to 1985 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Solar Rotation Rate Profile from 1915 to 1985, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Solar Rotation Rate Profile from 1915 to 1985 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1246397