35 research outputs found

    Variability of Jovian ion winds: an upper limit for enhanced Joule heating

    Get PDF
    It has been proposed that short-timescale fluctuations about the mean electric field can significantly increase the upper atmospheric energy inputs at Jupiter, which may help to explain the high observed thermospheric temperatures. We present data from the first attempt to detect such variations in the Jovian ionosphere. Line-of-sight ionospheric velocity profiles in the Southern Jovian auroral/polar region are shown, derived from the Doppler shifting of H<sub>3</sub><sup>+</sup> infrared emission spectra. These data were recently obtained from the high-resolution CSHELL spectrometer at the NASA Infrared Telescope Facility. We find that there is no variability within this data set on timescales of the order of one minute and spatial scales of 640 km, putting upper limits on the timescales of fluctuations that would be needed to enhance Joule heating

    The Structure and Motions of the 3C~120 Radio Jet on Scales of 0.6 to 300 Parsecs

    Get PDF
    Results are presented from long term VLBI monitoring of the parsec-scale radio jet in 3C120, primarily at 5 and 1.7 GHz. Numerous superluminal features are followed, some over large fractional distances from the core. The speeds of the features are not all the same, but vary by less than a factor of 2. The superluminal features extend to core distances of over 0.2 arcseconds and the region of slowing has not been found. The 1.7 GHz images show evidence for stationary features in addition to the superluminal features. The structure of the jet in the vicinity of the most likely stationary feature is suggestive of a helical pattern seen in projection. The deprojected wavelength of the pattern is very long relative to the jet radius, unlike the situation in sources such as M87. If the 3C120 jet does contain a slowly-moving, helical structure, then theory suggests that the jet resides in a relatively cool medium, not in a relativistically hot cocoon or lobe.Comment: 35 pages with 8 postscript figures. Accepted for publication in the Astrophysical Journa

    Variability of Jovian ion winds: an upper limit for enhanced Joule heating

    No full text
    It has been proposed that short-timescale fluctuations about the mean electric field can significantly increase the upper atmospheric energy inputs at Jupiter, which may help to explain the high observed thermospheric temperatures. We present data from the first attempt to detect such variations in the Jovian ionosphere. Line-of-sight ionospheric velocity profiles in the Southern Jovian auroral/polar region are shown, derived from the Doppler shifting of H3+ infrared emission spectra. These data were recently obtained from the high-resolution CSHELL spectrometer at the NASA Infrared Telescope Facility. We find that there is no variability within this data set on timescales of the order of one minute and spatial scales of 640 km, putting upper limits on the timescales of fluctuations that would be needed to enhance Joule heating

    Jupiter's Aurora as Imaged by the NASA IRTF and Comparison with Hubble Space Telescope Observations in the UV

    Full text link
    We investigate Jupiter's infrared aurora using observations from the NASA Infrared Telescope Facility from 1995-2000 as compared with observations in the UV from the Hubble Space Telescope

    Is the Jovian auroral H

    No full text
    Context. Measurement of linear polarisation in Earth’s thermospheric oxygen red line can be a useful observable quantity for characterising conditions in the upper atmosphere; therefore, polarimetry measurements are extended to other planets. Since FUV emissions are not observable from the ground, the best candidates for Jupiter auroral emissions are \hbox{H3+\textrm{H}_{3}^{+} } infrared lines near 4 μm. This ion is created after a chemical process in the Jovian upper atmosphere. Thus the anisotropy responsible of the polarisation cannot be the particle impact as in the Earth case. Aims. The goal of this study is to detect polarisation of \hbox{H3+\textrm{H}_{3}^{+} } emissions from Jupiter’s aurora. Methods. Measurements of the \hbox{H3+\textrm{H}_{3}^{+} } emissions from Jupiter’s southern auroral oval were performed at the UK Infrared Telescope using the UIST-IRPOL spectro-polarimeter, with the instrument slit positioned perpendicular to Jupiter’s rotation axis. Data were processed by dividing the slit into 24 bins. Stokes parameters (u, q and v), polarisation degree and direction were extracted for each bin and debiased. Results. More than 5 bins show polarisation with a confidence level above 3σ. Polarisation degrees up to 7% are detected. Assuming the auroral intensity is constant during the 8 waveplate positions exposure time, i.e. around 10 min, strong circular polarisation is present, with an absolute value of the Stokes v parameter up to 0.35. Conclusions. This study shows that polarisation is detectable in the Jovian infrared auroras, but new measurements are needed to be able to use it to characterise the ionospheric environment. At present, it is not possible to propose a mechanism to explain this polarisation owing to the lack of theoretical work and laboratory experiments concerning the polarisation of \hbox{H3+\textrm{H}_{3}^{+} }

    Development of a Framework and the Content for a Psychoeducational Internet-Delivered Intervention for Women after Treatment for Gynecological Cancer

    No full text
    The number of women treated for gynecological cancer is increasing. At the same time, the duration of in-patient hospitalization has decreased, and follow-up with its primary focus on early recognition of recurrence does not meet all patients' needs. One method of follow-up may be digital intervention. This study describes the development of a psychoeducational Internet-delivered intervention targeting women's psychosocial needs during the follow-up period after treatment for gynecological cancer. The project consisted of three phases following the UK Medical Research Council Framework guidelines for the development of complex interventions. Phase one identified the evidence in the field, phase two identified the relevant theoretical framework, and phase three included a two-year work process including focus group interviews and think aloud interviews with users. Through the steps of literature review, theoretical framework, and an iterative development process with users and other stakeholders, a six-week program was developed. The program included psychoeducational information, multimedia, exercises, and weekly telephone follow-up with a dedicated nurse. This Internet-delivered intervention can be a novel method for addressing the gap in the provision of follow-up for women after treatment for gynecological cancer
    corecore