List Of Figures

View Image Figure 1:
The solar wind velocity (red/blue line) and density (green line) observed by Ulysses as a function of ecliptic latitude (McComas et al., 2000). During solar minimum conditions, high latitudes are dominated by high speed, low density wind, while low latitudes see mostly lower speed wind with higher densities.
View Image Figure 2:
Map of the Local Bubble in the Galactic plane, where the contours indicate 20mÅ and 50mÅ equivalent widths for the Na I D2 line (Lallement et al., 2003). The distance scale is in parsecs.
View Image Figure 3:
Schematic picture of the heliospheric interface from Izmodenov et al. (2002), which can be divided into the 4 regions shown in the figure, with significantly different plasma properties. Region 1: supersonic solar wind; Region 2: subsonic solar wind; Region 3: disturbed interstellar gas and plasma; and Region 4: undisturbed interstellar medium.
View Image Figure 4:
(a) Proton temperature, (b) proton density, (c) neutral hydrogen temperature, and (d) neutral hydrogen density distributions for a heliospheric model from Wood et al. (2000b). The positions of the termination shock (TS), heliopause (HP), and bow shock (BS) are indicated in (a), and streamlines indicating the plasma flow direction are shown in (b). The distance scale is in AU.
View Image Figure 5:
HST/GHRS spectra of the Lyα lines of α Cen A and B, showing broad absorption from interstellar H I and narrow absorption from D I (Linsky and Wood, 1996).
View Image Figure 6:
Schematic diagram showing how a stellar Lyα profile changes from its initial appearance at the star and then through various regions that absorb parts of the profile before it reaches an observer at Earth: the stellar astrosphere, the LISM, and finally the heliosphere (Wood et al., 2003b). The lower panel shows the actual observed Lyα profile of α Cen B. The upper solid line is the assumed stellar emission profile and the dashed line is the ISM absorption alone. The excess absorption is due to heliospheric H I (green shading) and astrospheric H I (red shading).
View Image Figure 7:
Comparison between the Lyα spectra of α Cen B (green histogram) and Proxima Cen (red histogram) from Wood et al. (2001). The inferred ISM absorption is shown as a green dashed line. The Alpha/Proxima Cen data agree well on the red side of the H I absorption, but on the blue side the Proxima Cen data do not show the excess Lyα absorption seen toward α Cen (i.e. the astrospheric absorption).
View Image Figure 8:
Comparison of the H I absorption predicted by a four-fluid heliospheric model (dashed lines) and the observations, where the model heliospheric absorption is shown after having been added to the ISM absorption (dotted lines). Reasonably good agreement is observed, although there is a slight underprediction of absorption towards 36 Oph and Sirius, and a slight overprediction towards ε Eri (Wood et al., 2000b).
View Image Figure 9:
Distribution of H I density predicted by hydrodynamic models of the Alpha/Proxima Cen astrospheres, assuming stellar mass loss rates of (from top to bottom) 0.2M˙⊙, 0.5M˙⊙, 1.0M˙⊙, and 2.0M˙⊙ (Wood et al., 2001). The distance scale is in AU. Streamlines show the H I flow pattern.
View Image Figure 10:
Closeups of the blue side of the H I Lyα absorption lines for six stars with detected astrospheric absorption, plotted on a heliocentric velocity scale. Narrow D I ISM absorption is visible in all the spectra just blueward of the saturated H I absorption. Green dashed lines indicate the interstellar absorption alone, and blue lines in each panel show the additional astrospheric absorption predicted by hydrodynamic models of the astrospheres assuming various mass loss rates (Wood et al., 2002).
View Image Figure 11:
A figure analogous to Figure 10, but for six other lines of sight (Wood et al., 2005a).
View Image Figure 12:
Maps of H I density from hydrodynamic models of stellar astrospheres (Wood et al., 2002). The models shown are the ones that lead to the best fits to the data in Figure 10. The distance scale is in AU. The star is at coordinate (0,0) and the ISM wind is from the right. The dashed lines indicate the Sun–star line of sight.
View Image Figure 13:
Maps of H I density from hydrodynamic models of stellar astrospheres (Wood et al., 2005a), analogous to Figure 12. The models shown are the ones that lead to the best fits to the data in Figure 11.
View Image Figure 14:
Measured mass loss rates (per unit surface area) plotted versus X-ray surface flux (Wood et al., 2005a). The filled and open circles are main sequence and evolved stars, respectively. For the main sequence stars with logF < 8 × 105 ergscm −2s− 1 X, mass loss appears to increase with coronal activity, so a power law has been fitted to these stars, and the shaded region is the estimated uncertainty in the fit. The saturation line represents the maximum FX value observed from solar-like stars.
View Image Figure 15:
The mass loss history of the Sun suggested by the power law relation from Figure 14 (Wood et al., 2005a). The low mass-loss rate measurement for ξ Boo implies that the wind weakens at t ≈ 0.7Gyr as one goes back in time.