We present the results of a transcontinental campaign to observe the 2009 June 5 transit of the exoplanet HD 80606b. We report the first detection of the transit ingress, revealing the transit duration to be 11.64 ± 0.25 hr and allowing more robust determinations of the system parameters. Keck spectra obtained at midtransit exhibit an anomalous blueshift, giving definitive evidence that the stellar spin axis and planetary orbital axis are misaligned. The Keck data show that the projected spin-orbit angle λ is between 32-87 deg with 68.3% confidence and between 14-142 deg with 99.73% confidence. Thus the orbit of this planet is not only highly eccentric (e = 0.93) but is also tilted away from the equatorial plane of its parent star. A large tilt had been predicted, based on the idea that the planet's eccentric orbit was caused by the Kozai mechanism. Independently of the theory, it is noteworthy that all 3 exoplanetary systems with known spin-orbit misalignments have massive planets on eccentric orbits, suggesting that those systems migrate through a different channel than lower-mass planets on circular orbits.

Abstract. We have developed a method for displaying the spectral structure of Jupiter's decametric radio S bursts on timescales down to a few microseconds, 2 orders of magnitude finer than has been achieved elsewhere. By employing an extremely sensitive antenna (640 dipoles, at 26 MHz) and selecting only relatively weak S bursts that possess the simplest possible spectral shape, we identify frequently occurring structural features that we associate with localized emission centers. On timescales having better than about 30/•s resolution we find that the S burst baseband oscillation (and therefore the RF oscillation) is modulated to form distinct pulses, which we refer to as subpulses. Still finer time resolution reveals that within individual subpulses the baseband (and RF) oscillation often displays segments in which the usually drifting phase term abruptly becomes essentially constant and, after remaining so for 10 to 100 /•s, abruptly resumes its random drift. It is these abruptly starting and ending segments of phase coherence that we attribute to isolated powerful centers of cyclotron maser wave amplification, which happen for brief intervals to be the only ones that are active. We believe that the more usual phase-incoherent condition (i.e., one in which the instantaneous frequency drifts randomly within the emission band) is due to the fact that the resultant radiation is the sum of two or more components from neighboring wave amplification centers emitting at slightly different frequencies, with independently varying intensities. Possible models for the production of subpulses and phase coherent intervals are discussed.

We present ground-based optical observations of the September 2009 and January 2010 transits of HD 80606b. Based on 3 partial light curves of the September 2009 event, we derive a midtransit time of T c [HJD] = 2455099.196 ± 0.026, which is about 1σ away from the previously predicted time. We observed the January 2010 event from 9 different locations, with most phases of the transit being observed by at least 3 different teams. We determine a midtransit time of T c [HJD] = 2455210.6502 ± 0.0064, which is within 1.3σ of the time derived from a Spitzer observation of the same event.

An exceptional Jovian aurora was detected in the FUV on December 21, 1990, by means of Vilspa and Goddard Space Flight Center (GFSC) International Ultraviolet Explorer (IUE) observations. This event included intensification by a factor of three between December 20 and 21, leading to the brightest aurora identified in the IUE data analyzed, and, in the north, to a shift of the emission peak towards larger longitudes (these variations are even more dramatic once the actual source brightness distribution is retrieved from the raw data). The Jovian radio emission simultaneously recorded at decameter wavelengths in Nançay also exhibits significant changes, from a weak and short‐duration emission on December 20 to a very intense one, lasting several hours, on December 21. Confirmation of this intense radio event is also found in the observations at the University of Florida on December 21. The emissions are identified as right‐handed Io‐independent “A” (or “non Io‐A”) components from the northern hemisphere. The radio source region deduced from the Nançay observations lies, for both days, close to the UV peak emission, exhibiting in particular a similar shift of the source region toward larger longitudes from one day to the next. A significant broadening of the radio source was also observed and it is shown that on both days, the extent of the radio source closely followed the longitude range for which the UV brightness exceeds a given threshold (∼3 kW m−1). The correlated variations, both in intensity and longitude, strongly suggest that a common cause triggered the variation of the UV and radio emissions during this exceptional event. On one hand, the variation of the UV aurora could possibly be interpreted according to the Prangé and Elkhamsi (1991) model of diffuse multicomponent auroral precipitation (electron and ion): it would arise from an increase in the precipitation rate of ions together with an inward shift of their precipitation locus from L ≈ 10 to L ≈ 6. On the other hand, the analysis of Ulysses observations in the upstream solar wind suggests that a significant disturbance in the solar wind, involving the generation of an interplanetary shock and the presence of a CME have interacted with the Jovian magnetosphere at about the time of the auroral event. Both arguments suggest that we may have observed for the first time a magnetic storm‐type interaction in an outer planet magnetosphere, affecting simultaneously several auroral processes. Conversely, the observed relationship between the level of UV auroral activity and the detection of decameter emission (DAM), if it were a typical feature, might argue in favour of a more direct and permanent association between the auroral processes leading to UV and radio aurorae, possibly related to “discrete‐arc”‐like activity and electron precipitation.

The result of a measurement of the period of rotation of Jupiter's inner magnetosphere with unprecendented precision is presented. The measurement was made from the University of Florida database of 35 apparitions of Jovian decametric observations at frequencies of 18, 20, and 22 MHz between 1957 and 1994. The mean of our 24 independent measurements was 9h55m29s.685, and the standard deviation of the mean was 0s.0034. The System III (1965) Jovian rotation period value that is currently accepted by the International Astronomical Union is greater than our value by 7.4 times our standard deviation; it appears to be in need of revision. We set an upper limit of 27 milliseconds per year on a possible drift of the rotation period as measured by our method.