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Jupiter’s Radio Rotation Period: A 50-year Average

Jupiter’s Radio Rotation Period: A 50-year Average. C. A. Higgins and D. Solus Department of Physics & Astronomy Middle Tennessee State Univ., Murfreesboro, TN F. Reyes and the late T. D. Carr (Emeritus) Department of Astronomy University of Florida, Gainesville, FL.

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Jupiter’s Radio Rotation Period: A 50-year Average

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  1. Jupiter’s Radio Rotation Period: A 50-year Average C. A. Higgins and D. SolusDepartment of Physics & Astronomy Middle Tennessee State Univ., Murfreesboro, TN F. Reyes and the late T. D. Carr (Emeritus)Department of Astronomy University of Florida, Gainesville, FL

  2. History of Rotation Period measurements Galileo (1610) Schroeter (1787) Surface features Marth (1875, 1885) Jupiter ephemeris, Sys I and Sys II defined Williams (1896) nine zones of latitude Shain (1956) Radio Rotation Period Gallet (1957), Gardener and Shain (1958) Carr et al. (1958) - - - System III (1957) IAU (1962) --- first defined System III (1957) period 1960s and 70s many measurements: DAM and DIM Riddle & Warwick (1976) + 25 scientists agreed to the System III (1965) - - - 9h 55m 29.71s Duncan (1971) decimetric measurement Carr (1972) decametric measurement Kaiser & Alexander 1972) decametric & power spectrum Berge (1974) decimetric measurement IAU (1977) System III (1965) Sandel & Dessler (1988) System IV System IV

  3. Data CollectionUF Radio Observatory 18TL 18TR 20TL 20TR 22TL 22TR

  4. Source A Source B Source C Probability of Occurrence 5° bins Jupiter CML Ephemeris SysIII (1965)

  5. Declination Effect

  6. Jupiter Occurrence ProbabilityJovicentric Declination of Earth DE • Peaks are Source A Occurrence Probability • 12-yr Declination Effect (DE)

  7. CrossCorrelation Multiple 12-yr data CML shift < 0 Period < SysIII(1965) CML shift > 0 Period > SysIII(1965)

  8. Rotation Period Calculation P’ – new rotation period (in decimal hours) P – old rotation period (9.92492 h = 9h 55m 29.71s) Δt – time between observation epochs in years (this example t = 24.017 y or 210533 h) 360 – number of degrees per rotation  - degrees shift in longitude of the second histogram with respect to the first that maximizes the correlation coefficient (this example -6.8°) Example  = -6.8° → 9.92491 h ( = 9h 55m 29.68s)

  9. Rotation Period Calculations SysIII (1965) New Period Weighted Mean Period 9h 55m 29.689 ± 0.004s

  10. Rotation Period Drift SysIII (1965) New Period Weighted Mean Period 9h 55m 29.689 ± 0.004s Max Possible Drift ≈ 4 ms/yr (from Higgins et al., JGR 1997)

  11. Jupiter’s Internal Rotation Period Higgins et al. (1997) Sys III (1965) Yu & Russell (2009) Higgins et al. (MOP 2011) Rotation Periods  1σ

  12. Conclusions Jupiter’s DAM Rotation Period Weighted Mean Period 9h 55m 29.689s ± 0.004s Max Possible Drift ~ 4 ms/yr No conclusive secular variation Radio sources are stable over long term observations Discussion Differential rotation Other calculations IAU has returned the period back to Sys III (1965) IAU would like a response from the MOP community Thank you!

  13. Dr. Thomas D. Carr1917 - 2011 Entered UF at 16; M.S. in 1940 WWII (physicist at Aberdeen, MD) Worked with A-bomb tests at Bikini First PhD in Astrophysics at UF (1958) Co-founder of UFRO, Radio program Univ. of Chile Involved with creation of Arecibo radio telescope Designed and build a 26 MHz array of (640 dipoles) 2 Books and many book chapters (Jupiter, Physics of the Jovian Magnetosphere, Radio Astronomy) Co-investigator of PRA group for Voyager missions Jupiter radio emissions (rotation and S-bursts) ASTEROID #96288 named and dedicated for Tom Advised over 25 PhD and MS theses Pioneer in VLBI > 30 years UF Professor; Retired in 1995 Loved Florida’s natural habitat and its conservation

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