Physics
Scientific paper
May 2008
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008agusmsp21b..06f&link_type=abstract
American Geophysical Union, Spring Meeting 2008, abstract #SP21B-06
Physics
7522 Helioseismology, 7529 Photosphere, 7537 Solar And Stellar Variability (1650), 7544 Stellar Interiors And Dynamo Theory
Scientific paper
The RHESSI solar aspect sensors (SAS) serendipitously provide precise measures of the shape of the Sun at 670 nm. The data rate is high (more than 106 points since launch in 2002), and each point has a statistical precision of the order of 10 mas. We present reduced data from a three-month interval in 2004. The full data gives an oblateness (axisymmetric quadrupole shape term, expressed as the difference between equatorial and polar radii) of 10.74 ± 0.44 mas. For comparison, Dicke's 1970 estimate, based on uniform rotation, predicted 8.10 mas. The apparent radius strongly correlates with the EUV limb brightness. Accordingly, by restricting the data base to avoid faculae, including a component outside the active regions, we obtain a lower value for the oblateness. We find a value of 7.98 ± 0.14 mas. Based on a comparison of our results with previous balloon and satellite observations, the apparent excess oblateness may have a positive correlation with the solar cycle.
Fivian Martin D.
Hudson Hugh S.
Lin Robert P.
Zahid Jabran H.
No associations
LandOfFree
RHESSI Observations of a Large Excess Solar Oblateness and its Identification as Magnetic in Nature 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 RHESSI Observations of a Large Excess Solar Oblateness and its Identification as Magnetic in Nature, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and RHESSI Observations of a Large Excess Solar Oblateness and its Identification as Magnetic in Nature will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1402015