TY  - JOUR
AU  - Barthelemy M, Lystrup M. B.
PY  - 2011//
TI  - First detection of polarization in jovian auroral H+3 emissions
JO  - A&A
VL  - 530
KW  - polarization / molecular data / planets and satellites: aurorae / planets and satellites: individual: Jupiter
N2  - Context. The recent measurement of linear polarization in the Earth thermospheric oxygen red line shows that it can be a useful observable quantity to characterise the upper atmospheres conditions. Therefore, polarimetry measurements are extended to other planets. Considering that FUV emissions are not observable from the ground, the best candidates for Jupiter auroral emissions are H3+ infrared emissions around 4µm. This ion is created after a chemical process in the jovian upper atmosphere. Then, the anisotropy responsible of the polarization cannot be the particle impact as in the Earth case Aims. The goal of this study is to detect some potential linear polarisation in the H3+ emissions of the jovian auroral oval. Methods. Measurements of the H3+ emissions from the south auroral oval have been performed at the UKIRT during the beginning of August 2008, using the UIST-IRPOL spectro-polarimeter. The slit have been positioned perpendicularly to the jovian rotation axis. Data were processed by dividing the slit in 24 bins. Stokes parameters u and q, polarization degree and direction are extracted for each bin and debiased. Results. Polarization up to 8% is detected. More than 7 bins show polarization with confidence level above 3σ. The better signal to noise ratio appears in the main auroral oval but no clear link appears between the polarization degrees and angles and the local known anisotropies. The angles are a bit higher than 90° in the West part of the oval and mostly around 90° for the East part. Conclusions. This study shows that polarization is detectable in the jovian infrared auroras. However, it is impossible to link it with electric or magnetic field for the moment due to the lack of theoretical work and laboratory experiments concerning the polarization of H3+.
SN  - 1895-6572
UR  - http://dx.doi.org/10.1051/0004-6361/201014314
N1  - exported from refbase (http://publi.ipev.fr/polar_references/show.php?record=220), last updated on Wed, 29 Jun 2011 15:24:59 +0200
ID  - BarthelemyM2011
ER  -