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Title: HELIOSPHERIC ENERGETIC NEUTRAL HYDROGEN MEASURED WITH ASPERA-3 AND ASPERA-4

We re-analyze the signal of non-planetary energetic neutral atoms (ENAs) in the 0.4-5.0 keV range measured with the Neutral Particle Detector (NPD) of the ASPERA-3 and ASPERA-4 experiments on board the Mars and Venus Express satellites. Due to improved knowledge of sensor characteristics and exclusion of data sets affected by instrument effects, the typical intensity of the ENA signal obtained by ASPERA-3 is an order of magnitude lower than in earlier reports. The ENA intensities measured with ASPERA-3 and ASPERA-4 now agree with each other. In the present analysis, we also correct the ENA signal for Compton-Getting and for ionization loss processes under the assumption of a heliospheric origin. We find spectral shapes and intensities consistent with those measured by the Interstellar Boundary Explorer (IBEX). The principal advantage of ASPERA with respect to the IBEX sensors is the two times better spectral resolution. In this study, we discuss the physical significance of the spectral shapes and their potential variation across the sky. At present, these observations are the only independent test of the heliospheric ENA signal measured with IBEX in this energy range. The ASPERA measurements also allow us to check for a temporal variation of the heliospheric signal asmore » they were obtained between 2003 and 2007, whereas IBEX has been operational since the end of 2008.« less
Authors:
;  [1] ; ;  [2] ; ; ;  [3] ;  [4] ;  [5]
  1. Physics Institute, University of Bern, Bern 3012 (Switzerland)
  2. The Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20723 (United States)
  3. Space Research Centre, Polish Academy of Sciences, Warsaw 00-716 (Poland)
  4. Space Research Institute (IKI), Moscow 117997 (Russian Federation)
  5. The Swedish Institute of Space Physics, Kiruna SE-981 28 (Sweden)
Publication Date:
OSTI Identifier:
22270911
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 775; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; ATOMS; ENERGY LOSSES; HELIOSPHERE; HYDROGEN; KEV RANGE; NEUTRAL PARTICLES; SATELLITES; SENSORS; SOLAR WIND; SUN; VARIATIONS