Taking the Pulse of the Gas Giants

Distinguishing between competing formation theories for our Solar System requires revealing the deep internal structure of the gas giants. Helioseismology has been remarkably successful in probing the deep internal structure of the Sun, and the gas giants also consist primarily of hydrogen and helium with deep convective fluid envelopes, so similar techniques should be applicable to the Jovian planets. Planetary seismology is in its infancy and consists of identifying global acoustic pressure-modes by measuring radial velocity shifts of reflected Solar light from the Jovian clouds. Previous attempts to detect these global oscillations for Jupiter were inconclusive due to contamination of the frequency spectrum by the inevitable diurnal cycle experienced at low latitudes, and the relatively short length of the observing run. To advance on previous work, we have developed and built a dual-channel instrument — a Doppler imager to detect radial velocity shifts of the 589 nm Sodium lines and the 770 nm Potassium line, and a snapshot linear-Stokes imaging polarimeter to collect complimentary information on the Jovian atmospheric levels in the 889 nm Methane absorption band. With these instruments on the AEOS 3.6m telescope, we collected an unprecedented set of observations: 24 consecutive days of data collection on Jupiter with an average duty cycle of ~24% in three simultaneous bandpasses, providing the longest-duration velocimetry and polarization measurements of Jupiter to date. We present preliminary results from this observing run in an attempt to unambiguously measure the frequencies of the individual global modes of the Gas Giants for the first time.