We present an analysis of Voyager UVS data obtained between 1993 and mid-2007. These data are used to study the interplanetary background and the hydrogen number density in the outer heliosphere. Two types of observations are studied, first the heliospheric scans performed until 2003 and then the fixed line of sight observations, close to the upwind direction, which are still performed at the end of 2007.
We make comparisons with models including multiple scattering and hydrogen distributions derived from self-consistent modeling of the interface region. It is found that there is a remaining discrepancy between models and data. The origin of this difference is unknown but it may be linked to a possible tilting of the heliospheric interface due to the presence of an interstellar magnetic field.
We should also estimate alternate sources of emission which are not backscattering of solar photons like collisional excitation of hydrogen in the heliosheath and emission after charge transfer or recombination of proton and electron in HII regions.
Line profiles from HST/STIS are also presented.
Outer heliosphere Interplanetary background Hydrogen distribution
This is a preview of subscription content, log in to check access.
V.B. Baranov, Yu.G. Malama, Model of the solar wind interaction with the local interstellar medium: numerical solution of self-consistent problem. J. Geophys. Res. 98(A9), 15157–15163 (1993)
J.L. Bertaux, J.E. Blamont, Evidence for an extra-terrestrial Lyman-alpha emission, the interstellar wind. Astron. Astrophys. 11, 200 (1971)
J.L. Bertaux, E. Kyrölä, E.R. Quémerais, R. Lallement, W. Schmidt et al., SWAN: A study of solar wind anisotropies on SOHO with Lyman alpha sky mapping. Sol. Phys. 162, 403–439 (1995)
D.T. Hall, D.E. Shemansky, D.L. Judge, P. Gangopadhyay, M.A. Gruntman, Heliospheric hydrogen beyond 15 AU—Evidence for a termination shock. J. Geophys. Res. 98(A9), 15,185–15,192 (1993). (ISSN 0148-0227)
V. Izmodenov, M. Gruntman, Y.G. Malama, Interstellar hydrogen atom distribution function in the outer heliosphere. J. Geophys. Res. 106(A6), 10681–10690 (2001)
V. Izmodenov, Y.G. Malama, M.S. Ruderman, Solar cycle influence on the interaction of the solar wind with Local Interstellar Cloud. Astron. Astrophys. 429, 1069–1080 (2005a)
V.V. Izmodenov, Y.G. Malama, M.S. Ruderman, Modeling of the outer heliosphere with the realistic solar cycle. Adv. Space Res. 41(2), 318–324 (2008)
R. Lallement, E. Quémerais, J.L. Bertaux, S. Ferron, D. Koutroumpa, R. Pellinen, Deflection of the interstellar neutral hydrogen flow across the heliospheric interface. Science 307(5714), 1447–1449 (2005)
E. Quemerais, Y.G. Malama, B.R. Sandel, R. Lallement, J.-L. Bertaux, V.B. Baranov, Outer heliosphere Lyman alpha background derived from two-shock model hydrogen distributions: application to the Voyager UVS data. Astron. Astrophys. 308, 279–289 (1996)
E. Quémerais, J.-L. Bertaux, R. Lallement, M. Berthé, E. Kyrölä, W. Schmidt, Interplanetary Lyman alpha line profiles derived from SWAN/SOHO hydrogen cell measurements: Full-sky velocity field. J. Geophys. Res. 104(A6), 12585 (1999)
E. Quémerais, V. Izmodenov, Effects of the heliospheric interface on the interplanetary Lyman alpha glow seen at 1 AU from the Sun. Astron. Astrophys. 396, 269–281 (2002)
E. Quémerais, J.-L. Bertaux, R. Lallement, B.R. Sandel, V. Izmodenov, Voyager 1/UVS Lyman a glow data from 1993 to 2003: Hydrogen distribution in the upwind outer heliosphere. J. Geophys. Res. 108(A10), LIS4–1 (2003)
G.E. Thomas, R.F. Krassa, OGO 5 measurements of the Lyman alpha sky background. Astron. Astrophys. 11, 218 (1971)
T.N. Woods, F.G. Eparvier, S.M. Bailey, P.C. Chamberlin, J. Lean, G.J. Rottman, S.C. Solomon, W.K. Tobiska, D.L. Woodraska, Solar EUV Experiment (SEE): Mission overview and first results. J. Geophys. Res. 110(A1) (2005). CiteID A01312