1 research outputs found
Detection of Gravitational Redshift on the Solar Disk by Using Iodine-Cell Technique
With an aim to examine whether the predicted solar gravitational redshift can
be observationally confirmed under the influence of the convective Doppler
shift due to granular motions, we attempted measuring the absolute spectral
line-shifts on a large number of points over the solar disk based on an
extensive set of 5188-5212A region spectra taken through an iodine-cell with
the Solar Domeless Telescope at Hida Observatory. The resulting heliocentric
line shifts at the meridian line (where no rotational shift exists), which were
derived by finding the best-fit parameterized model spectrum with the observed
spectrum and corrected for the earth's motion, turned out to be weakly
position-dependent as ~ +400 m/s near the disk center and increasing toward the
limb up to ~ +600 m/s (both with a standard deviation of sigma ~ 100 m/s).
Interestingly, this trend tends to disappear when the convectiveshift due to
granular motions (~-300 m/s at the disk center and increasing toward the limb;
simulated based on the two-component model along with the empirical
center-to-limb variation) is subtracted, finally resulting in the averaged
shift of 698 m/s (sigma = 113 m/s). Considering the ambiguities involved in the
absolute wavelength calibration or in the correction due to convective Doppler
shifts (at least several tens m/s, or more likely up to <~100 m/s), we may
regard that this value is well consistent with the expected gravitational
redshift of 633 m/s.Comment: 28 pages, 12 figures, electronic materials as ancillary data (table3,
table 4, ReadMe); accepted for publication in Solar Physic