All Figures

$\begin{figure} \par\includegraphics[height=15.5cm,clip]{fig1a_new.ps} %\end{figure}$ Figure 1: The normalised spectrum of 4U 1907+09 from 4700 Å to 7200 Å. Arrows labelled "?'' indicate unidentified features; those labelled "G'' refer to the position of candidate DIBs, from the Galazutdinov et al. (2000) survey, that are not listed by Tuairisg et al. (2000) for BD +63 1964. The synthetic DIB spectrum of BD +63 1964 ( $\ensuremath {{E}_{(B-V)}}$ = 1.01 mag; Tuairisg et al. 2000) is scaled to the reddening of 4U 1907+09 and shown with a small offset (continuum is unity), shortwards of 6820 Å. Longwards of 6700 Å the DIB spectrum of HD 183143 is shown ( $\ensuremath {{E}_{(B-V)}}$ = 1.28 mag; Jenniskens & Desert 1994), scaled to the reddening of 4U 1907+09. Both synthetic spectra are also redshifted to match the observed DIB positions. Note the detail and wealth of the DIBs in all spectra. Figure 3 gives a close-up of four strong DIBs. Stellar photospheric and wind lines are identified by the corresponding atom/ion (see also Cox et al. 2005). Gaps in the spectral coverage are due to gaps between orders, between the three CCD detectors, and between UVES settings. The synthetic constructed DIB spectrum for 4U 1907+09, derived from Table 2 and shown in its entirety in Fig. 2, is plotted in light grey on top of the observed spectrum.
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In the text

$\begin{figure} \par\includegraphics[height=15.5cm,clip]{fig1b_new.ps} %\end{figure}$ Figure 1: continued. The normalised spectrum of 4U 1907+09 from 7200 Å to 9900 Å. Note that we observe the two DIBs at 9577 Å and 9632 Å that are tentatively attributed to the C₆₀⁺ molecule (Foing & Ehrenfreund 1994,1997).
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In the text

$\begin{figure} \par\includegraphics[width=15.5cm,clip]{fig1c_new.ps} \end{figure}$ Figure 1: continued. The normalised spectrum of 4U 1907+09 from 9900 Å to 10 400 Å. Weak narrow C₂ lines are seen near 8765 and 10148 Å. The bottom left and right panels show a zoomed view of the spectral ranges of these C₂ (2-0) and (1-0) Philips system transitions, respectively. See e.g. Van Dishoeck & Black (1989) and references therein for transition levels and wavelengths.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.8cm,clip]{2340fig2.ps} \end{figure}$ Figure 2: Entire synthetic DIB spectrum (4650 to 9950 Å) for 4U 1907+09 generated from the 180 identified DIBs and measured absorption features and their respective central wavelength positions ( $\lambda _{\rm DIB}$ ), equivalent widths ( EW) and full width at half maximum ( FWHM). This spectrum does not include stellar features nor atomic interstellar lines.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.8cm,clip]{2340fig3.ps} \end{figure}$ Figure 3: Normalised spectra of four prominent DIBs (at 5780, 5797, 6270, 6284 Å) are shown. These illustrate the strength of DIBs in 4U 1907+09, as well as the spectral quality obtained. For comparison the synthetic spectrum of BD +63 1964 (Tuairisg et al. 2000) is plotted on top with a small vertical offset, and with a wavelength shift to match the 4U 1907+09 DIBs. The 6284 Å DIB has been corrected with the telluric standard star HD 165470. The small spikes on the spectrum (near and on the 6284 Å DIB) are the remnants of the telluric lines. See Sect. 2 for details on the telluric line correction method. The stellar C IV line at 5802 Å is characteristic of an O8/9 supergiant type (Cox et al. 2005).
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.8cm,clip]{2340fig4a.ps}\hs... ...raphics[angle=-90,width=8.8cm,clip]{2340fig4c.ps}\hspace*{4.5cm}} \end{figure}$ Figure 4: Equivalent width of the 5780 Å ( top left panel), 5797 Å (top right panel) and 6613 Å (bottom panel) DIBs as a function of reddening $\ensuremath {{E}_{(B-V)}}$ for Galactic sightlines. The 5780 Å DIB strengths are taken from Herbig 1993 ( $\circ$ ), Chlewicki et al. 1986 ( $\blacksquare$ ), Thorburn et al. 2003 ( $\square$ ), Galazutdinov et al. 2004 ( $\times$ ) and this work ( $\Diamondblack$ , see Table 4). The 5797 Å DIB data points are taken from Chlewicki et al. 1986 ( $\ast$ ), Herbig 1993 ( $\circ$ ), Kreowski et al. 1999 ( $\square$ ), Benvenuti & Porceddu 1989 (+), Thorburn et al. 2003 ( $\Diamond$ ), Tuairisg et al. 2000 ( $\triangle$ ), Galazutdinov et al. 2004 ( $\times$ ) and this work ( $\Diamondblack$ ). Values for the narrow strong 6613 Å DIB are taken from Thorburn et al. 2003 ( $\cdot$ ), Sonnentrucker et al. 1997 ( $\diamond$ ), Rawlings et al. 2003 ( $\square$ ), Tuairisg et al. 2000 ( .) and this work ( $\Diamondblack$ ). The data sets plotted in the three panels, constitute a non-exhaustive compilation of lines of sight that probe a range of Galactic interstellar environments. We show in the top panel the two 5780 Å DIB equivalent width versus reddening relations for the interstellar clouds in the line of sight towards HD144217 and HD145797, which are typical for $\sigma$ and $\zeta$ type cloud DIB behaviour, respectively. Errors (not shown in figure) are 5 to 20% in $\ensuremath {{E}_{(B-V)}}$ and less than 10% in equivalent width. In all three panels we show the linear regression fit to the plotted dataset (dashed line). We excluded the highly reddened data points from the linear fit: for the 5797 Å DIB the two highly reddened Cygnus targets were excluded; for the 5780 Å DIB 4U 1907+09 was omitted; and for the 6613 Å DIB the Rawlings et al. (2003) data were not included.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=12cm,clip]{2340fig5.ps} %\end{figure}$ Figure 5: Panel a) shows the K I (7698.98 Å) profile observed towards 4U 1907+09, which gives an indication of the velocity and density distribution of the ISM gas (from Cox et al. 2005). The narrow (intrinsic) 6613 and 5797 Å DIB profiles observed towards HD 149757 (Sarre et al. 1995; Kerr et al. 1998) are shown in panels b) and c), respectively. The bottom panels d) and e) show the result of the convolution (solid) of the narrow single cloud DIBs with the 4U 1907+09 K I profile, respectively, as well as the respective observed 4U 1907+09 DIB profiles (dashed). The convolutions (solid) are scaled in intensity and shifted in velocity to match both the maximum depth and central velocity of the observed profile.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.8cm,clip]{2340fig6.ps} \end{figure}$ Figure 6: The 5780 DIB strength versus the H I column density towards the HMXB systems from this work (+) and the lines of sight in Herbig (1993) ( $\times$ ). The correlation coefficient for the HMXB subset is 0.93, while that of the combined data is 0.82.
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In the text

$\begin{figure} \par\includegraphics[height=15.5cm,clip]{fig1b_new.ps} %\end{figure}$	Figure 1: continued. The normalised spectrum of 4U 1907+09 from 7200 Å to 9900 Å. Note that we observe the two DIBs at 9577 Å and 9632 Å that are tentatively attributed to the C₆₀⁺ molecule (Foing & Ehrenfreund 1994,1997).
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$\begin{figure} \par\includegraphics[angle=-90,width=8.8cm,clip]{2340fig2.ps} \end{figure}$	Figure 2: Entire synthetic DIB spectrum (4650 to 9950 Å) for 4U 1907+09 generated from the 180 identified DIBs and measured absorption features and their respective central wavelength positions ( $\lambda _{\rm DIB}$ ), equivalent widths ( EW) and full width at half maximum ( FWHM). This spectrum does not include stellar features nor atomic interstellar lines.
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$\begin{figure} \par\includegraphics[angle=-90,width=8.8cm,clip]{2340fig6.ps} \end{figure}$	Figure 6: The 5780 DIB strength versus the H I column density towards the HMXB systems from this work (+) and the lines of sight in Herbig (1993) ( $\times$ ). The correlation coefficient for the HMXB subset is 0.93, while that of the combined data is 0.82.
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