All Figures

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{0834Fig1.eps} \end{figure}$ Figure 1: Perspective view of the inner heliosphere with the interstellar He flow and the resulting focusing cone, as modeled by J. Raymond (Michels et al. 2002; Lallement et al. 2004a), based on a hot model of the interstellar gas. A line-of-sight through the near-Sun cone, as obtained with SOHO UVCS in December, is indicated in orange. Also shown is a scan across the focusing cone in the He I 58.4 nm line glow from a February location with EUVE, as an example for the determination of the He parameters from the cone shape (Vallerga et al. 2004). A typical location of Ulysses during the neutral He observations is shown together with a sample of a sky image of the inflowing He distribution, from which the physical parameters were derived (Witte 2004). Finally, the dark blue line that extends from the Earth to the Sun indicates a sample accumulation of He⁺ pickup ion spectra in the ecliptic plane with ACE SWICS, and the green line shows the corresponding accumulation with Ulysses SWICS (Gloeckler et al. 2004).
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In the text

$\begin{figure} \par\includegraphics[width=14cm,clip]{0834Fig2.eps} \end{figure}$ Figure 2: Flowchart of the different observations and modeling involved in the coordinated analysis effort towards the interstellar He parameters. Rectangular boxes indicate observations that were used, the rounded boxes indicate modeling used to either derive parameters or to reproduce observations. The arrows indicate the flow in the analysis, either from observation to derived parameter or from parameter used to additional implications. The oval boxes contain the main results, i.e. the He parameters ( top) with a color-coding that indicates the primary method, from which the values were derived, and implications that need future attention ( bottom), as deduced from this analysis.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{0834Fig3.eps} \end{figure}$ Figure 3: Schematic view of the He cone in the ecliptic plane and its observation through pickup ions and UV scattering. The pickup ion phase space density as a function of $v/v_{\rm SW}$ obtained with ACE SWICS represents the radial density profile inside the Earth's orbit ( top). With SOHO UVCS a line-of-sight integral through the near Sun cone is taken at 5, 7, and 9 $R_{\rm s}$ below the Sun, i.e. it cuts through the cone at 0.15-0.24 AU in December and 0.2-0.5 AU in June ( lower left). EUVE provides a line-of-sight integral through the cone that is most sensitive just outside 1 AU ( lower right). In addition, EUVE obtained 360 $^{\circ }$ latitudinal scans of the cone in October and February (center).
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{0834Fig4.eps} \end{figure}$ Figure 4: Compilation and comparison of the independently obtained results for the interstellar He parameters. Top: latitude $\beta$ versus longitude $\lambda$ of the interstellar gas flow vector from Ulysses GAS observations (Witte 2004) and from UV backscattering observations of the cone with EUVE (Vallerga et al. 2004) and Prognoz 6 (Lallement et al. 2004b; Dalaudier et al. 1984) along with a weighted mean of the two results. Also shown is the determination of $\lambda$ from the averaged pickup ion observations of the cone (Gloeckler et al. 2004). Bottom: He temperature $T_{\rm He\infty }$ versus inflow speed $v_{\rm He\infty }$ from Ulysses GAS and EUVE observations along with the weighted mean. For comparison the LIC parameters obtained from absorption lines in nearby spectra is shown (Linsky et al. 1993; Lallement & Bertin 1992).
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In the text