Energetic Neutral Atom (ENA) intensity gradients in the heliotail during year 2003, using Cassini/INCA measurements

13th Annual International Astrophysics Conference: Voyager, IBEX, and the Interstellar Medium

物理学;天文学

Dialynas, K.^1 ; Krimigis, S.M.^1,2 ; Mitchell, D.G.^2 ; Roelof, E.C.^2

Office of Space Research and Technology, Academy of Athens, Athens

106 79, Greece^1

Applied Physics Laboratory, Johns Hopkins University, Laurel

MD, United States^2

关键词: Energetic neutral atoms;    Intensity distribution;    Intensity gradients;    Ion and neutral cameras;    Magnetic field configurations;    Plasma pressures;    Smooth boundary;    Transition regions;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/577/1/012007/pdf
DOI  :  10.1088/1742-6596/577/1/012007

学科分类：天文学(综合)

来源: IOP

【 摘 要 】

In the present study we use all-sky energy-resolved (5-55 keV) energetic neutral atom (ENA) maps obtained by the Ion and Neutral CAmera (INCA) on board Cassini during the time period DOY 265/2003 to 268/2003, to investigate the properties of the peak-to-basin ENA emissions in the direction of the heliotail. Our conclusions can be summarized as follows: (1) a relatively smooth boundary (called "transition region") between the very low (basin) and high (tail) ENA emissions from the heliosheath, with a spatial width of ∼30° deg in ecl. longitude, that no theory had predicted to date, is identified in the energy range of 5-55 keV; (2) the ENA intensity gradient in this transition region is almost invariant as a function of both ecl. Latitude and energy, with an average value of ∼2.4% per degree; (3) the deduced partial plasma pressure distributions in the 5-55 keV energy range are consistent with the ENA intensity distributions in the same energy range, while the ENA intensity gradient translates to a corresponding partial pressure gradient that occurs in the transition region; and (4) this partial pressure gradient is possibly not consistent with a tail magnetic field configuration that is similar to the measured magnetic fields by the Voyagers in the nose hemisphere.