Speaker
Prof.
MARCELO EMILIO
(Ponta Grossa State University)
Description
Some of the earliest searches for global solar observations were obtained using the solar limb. Before p-modes had been clearly established by full-disk measurements, the solar limb offered a relatively simple opportunity for measuring the effects of local solar atmosphere oscillatory temperature and opacity changes, and effects from potentially small Lagrangian radial displacements in the solar limb due to interior oscillations. First thoughts might suggest that a time-series of effectively one-dimensional limb measurements couldn't compete with the physical information content of two-dimensional full-disk observations for a solar oscillation spectrum as complex as we know the p-mode spectrum to be. Yet, because high accuracy limb data can now be obtained with sufficient temporal resolution to isolate otherwise spatially degenerate modes in the limb-only data, and because the limb data sample a unique weighting of p-mode properties, there is reason to further develop some techniques of "limb-helioseismology." The other compelling reason for limb-helioseismology is that the existence of limb measurements from space, where there is no incoherent terrestrial image distortion noise, allows the solar limb to be measured astrometrically with exquisite precision. This means that oscillatory changes in spatial limb-harmonics, e.g. in data from HMI, can be measured even with sub-microarcsecond astrometric amplitudes. Individual spherical harmonic p-modes are detected in full-disk data with amplitudes of a few 10's of cm/s. This corresponds to 5-minute period oscillatory displacement amplitudes at the limb at the micro-arcsecond level. In this work we present results from Individual spherical harmonic p-modes that were detected around solar limb with amplitudes at the micro-arcsecond level from three years of measurements using the Helioseismic and Magnetic Imager (HMI) abord the Solar Dynamics Observatory (SDO). Those measurements of 5-min p-modes, while having many similarities to full-disk doppler observations, have significantly different sensitivities to the solar rotation and the 5-min mode solar atmospheric structure. These may provide information about the solar structure which is complementary to full-disk measurements.
Primary author
Prof.
MARCELO EMILIO
(Ponta Grossa State University)
Co-authors
Mr
Ian Cunnyngham
(IFA-UH)
Prof.
Jeff Kuhn
(IFA-UH)
Dr
Rock Bush
(Stanford University)
Dr
Scholl Isabelle
(IFA-UH)
