تقرير
Determining the beaming of Io decametric emissions : a remote diagnostic to probe the Io-Jupiter interaction
| العنوان: | Determining the beaming of Io decametric emissions : a remote diagnostic to probe the Io-Jupiter interaction |
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| المؤلفون: | Lamy, L., Colomban, L., Zarka, P., Prangé, R., Marques, M. S., Louis, C., Kurth, W., Cecconi, B., Girard, J., Griessmeier, J. -M., Yerin, S. |
| سنة النشر: | 2022 |
| المجموعة: | Astrophysics Physics (Other) |
| مصطلحات موضوعية: | Astrophysics - Earth and Planetary Astrophysics, Physics - Space Physics |
| الوصف: | We investigate the beaming of 11 Io-Jupiter decametric (Io-DAM) emissions observed by Juno/Waves, the Nan\c cay Decameter Array and NenuFAR. Using an up-to-date magnetic field model and three methods to position the active Io Flux Tube (IFT), we accurately locate the radiosources and determine their emission angle $\theta$ from the local magnetic field vector. These methods use (i) updated models of the IFT equatorial lead angle, (ii) ultraviolet (UV) images of Jupiter's aurorae and (iii) multi-point radio measurements. The kinetic energy $E_{e-}$ of source electrons is then inferred from $\theta$ in the framework of the Cyclotron Maser Instability. The precise position of the active IFT achieved from methods (ii,iii) can be used to test the effective torus plasma density. Simultaneous radio/UV observations reveal that multiple Io-DAM arcs are associated with multiple UV spots and provide the first direct evidence of an Io-DAM arc associated with a trans-hemispheric beam UV spot. Multi-point radio observations probe the Io-DAM sources at various altitudes, times and hemispheres. Overall, $\theta$ varies a function of frequency (altitude), by decreasing from $75^\circ-80^\circ$ to $70^\circ-75^\circ$ over $10-40$ MHz with slightly larger values in the northern hemisphere, and independently varies as a function of time (or longitude of Io). Its uncertainty of a few degrees is dominated by the error on the longitude of the active IFT. The inferred values of $E_{e-}$ also vary as a function of altitude and time. For the 11 investigated cases, they range from 3 to 16 keV, with a $6.6\pm2.7$ keV average. |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1029/2021JA030160 |
| URL الوصول: | http://arxiv.org/abs/2203.10797 |
| رقم الأكسشن: | edsarx.2203.10797 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1029/2021JA030160 |
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