English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Energetic neutral atoms (ENA) are an important tool for investigating thestructure of the heliosphere. Recently, it was observed that fluxes of ENAs(with energy $\le$ 55 keV) coming from the upwind and downwind regions of theheliosphere are similar in strength. This led the authors of these observationsto hypothesize that the heliosphere is bubble-like rather than comet-like,meaning that it has no extended tail. We investigate the directionaldistribution of the ENA flux for a wide energy range (3--88 keV) including theobservations from IBEX (Interstellar Boundary Explorer), INCA (Ion and NeutralCamera, on board Cassini), and HSTOF (High energy Suprathermal Time Of Flightsensor, on board SOHO, Solar and Heliospheric Observatory). An essentialelement is the model of pickup ion acceleration at the termination shock (TS)proposed by Zank. We use state of the art models of the global heliosphere,interstellar neutral gas density, and pickup ion distributions. The results,based on the "comet-like" model of the heliosphere, are close in flux magnitudeto ENA observations by IBEX, HSTOF and partly by INCA (except for the 5.2-13.5keV energy channel). We find that the ENA flux from the tail dominates at highenergy (in agreement with HSTOF, but not INCA). At low energy, our comet-likemodel produces the similar strengths of the ENA fluxes from the upwind anddownwind directions, which, therefore, removes this as a compelling argumentfor a bubble-like heliosphere.

Heliospheric structure as revealed by the 3 -- 88 keV H ENA spectra