Abundances and Depletions of Neutron-capture Elements in the Interstellar Medium

The primary aim of our extensive search of the HST/STIS archive was the identification of sight lines showing significant absorption from As ii λ1263, Cd ii λ2145, Sn ii λ1400, and Pb ii λ1433. While these lines are the principal transitions used to study these species in diffuse interstellar clouds, they are only rarely seen in UV spectra (although Sn ii λ1400 is somewhat more common than the others). To construct our sample, we started by examining the sight lines analyzed by R11 in their survey of B ii absorption in the diffuse ISM. The absorption features sought in the present survey are expected to have similar strengths compared to B ii λ1362. Moreover, for each of the directions studied by R11, we have detailed knowledge of the line-of-sight component structure from moderately strong absorption lines of dominant ions such as O i λ1355. This facilitates the search for weak features from other dominant ions that are expected to exhibit similar absorption profiles. We also expanded our search by examining the available STIS data for all other sight lines in the HST archive with the necessary wavelength coverage, considering observations acquired using either the high-resolution gratings (E140H and E230H) or the medium-resolution gratings (E140M and E230M) of the STIS FUV and NUV Multi-Anode Microchannel Array (MAMA) detectors. We noted any sight lines that showed apparent absorption from one or more of the four principal lines of interest at a velocity similar to that of O i λ1355. This process resulted in 14 sight lines being added to our initial list of 55 from the B ii survey, yielding our primary sample of 69 interstellar sight lines. (We included all 55 sight lines from R11 in our primary sample—even those that were not suspected of having absorption from As ii, Cd ii, Sn ii, or Pb ii—because the STIS data for these sight lines had already been processed, and thus it was straightforward to calculate upper limits for any nondetections.)

Each preliminary detection of As ii λ1263, Cd ii λ2145, Sn ii λ1400, and Pb ii λ1433 was scrutinized in detail, and in some cases, we found that either the absorption was not significant enough (i.e., the equivalent width was smaller than twice the estimated uncertainty), or the velocity deviated too severely from the expected velocity (i.e., by more than 2−4 km s⁻¹, depending on the spectral resolution). In such cases, it may be that the apparent absorption feature is simply an artifact of noise or is of instrumental origin. In the final analysis (see Section 3.2), we found that 32 sight lines from our primary sample did not exhibit compelling evidence for absorption from at least one of the four main species of interest. We chose not to eliminate these sight lines from our sample, however, since upper limits on column densities can still prove useful, particularly for interpreting the abundances of elements with relatively few confirmed detections (as we demonstrate in Section 4.3). Moreover, while these sight lines do not yield detections for any of the rare n-capture species, they each provide information on at least one of the more common species (i.e., Ga ii, Ge ii, and/or Kr i), which constitute an important part of our overall survey.

Ultimately, through our extensive examination of STIS archival data, we identified 10 sight lines with secure detections of As ii λ1263, 7 sight lines with detections of Cd ii λ2145, 27 sight lines with detections of Sn ii λ1400, and 8 sight lines with detections of Pb ii λ1433. Heidarian et al. (2015) recently reported the first detection in the ISM of the Pb ii transition at 1203.6 Å from a composite spectrum obtained by co-adding high-resolution HST/STIS spectra for more than 100 sight lines. Their analysis indicated that the 1203.6 Å line is about a factor of two stronger intrinsically than the line at 1433.9 Å. However, in a typical interstellar sight line, where log N(H i) ∼ 21.2, the 1203.6 Å line is positioned in a region of the spectrum where the flux is depressed by the damping wing of the nearby Lyα line, limiting the potential usefulness of this feature. Nevertheless, following the discovery of the Pb ii λ1203 line in a composite spectrum by Heidarian et al. (2015), we re-examined the archival STIS data to try to identify individual sight lines displaying this feature. Here, we report the detection of Pb ii λ1203 in four individual sight lines, bringing our total number of Pb ii detections to 12. We also searched for the weaker line of the Cd ii doublet at 2265.7 Å, and found this line in each of the seven directions where Cd ii λ2145 was detected.

In addition to searching for absorption from As ii, Cd ii, Sn ii, and Pb ii, we sought to incorporate available data on Ga ii, Ge ii, and Kr i into our analysis so that the abundances of all seven n-capture elements could be analyzed in a consistent manner. Column densities for Ga ii were previously reported by R11 for many of the sight lines in their B ii survey. Of the 14 additional sight lines added to our current sample, 5 have archival STIS data covering the Ga ii transition at 1414.4 Å, and all 5 exhibit significant Ga ii absorption. Published column densities for Ge ii and Kr i are also available for many of the sight lines in our sample. Twenty-five of our sight lines have Ge ii column densities listed in Cartledge et al. (2006), while a somewhat different subset of 25 sight lines has Kr i column densities given in Cartledge et al. (2003, 2004, 2008). All of these Ge ii and Kr i measurements were deduced from STIS observations. One of the sight lines in our sample (ζ Per) has a published Kr i column density from GHRS observations (Cardelli & Meyer 1997). To maintain consistency in how each sight line in our primary sample was analyzed across all of the elements of interest, we re-examined the STIS data on Ge ii λ1237 and Kr i λ1235 for each direction with a previously reported Ge ii or Kr i column density. We also sought to obtain Ge ii and Kr i column densities for any other sight lines in our sample without existing determinations in the literature.

For one of our primary targets (X Per), the available STIS data do not cover the Ge ii λ1237 or Kr i λ1235 lines, but other archival data are available for these species. To derive the Ge ii column density toward X Per, we examined GHRS data on Ge ii λ1237, along with STIS data for the weaker Ge ii line at 1602.5 Å. The Kr i column density that we derive for X Per is based on an analysis of the Kr i λ1164 line, which is available from observations made with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite. (While our intention in carrying out our archival survey was to focus exclusively on STIS data, the inclusion of the GHRS and FUSE data sets toward X Per meant that we could derive reliable abundances for all seven n-capture elements in this direction.) For another one of our sight lines (HD 99890), R11 reported column densities based on a single, relatively short STIS exposure obtained with the medium-resolution (E140M) grating. In the years since R11 published their study, new high-resolution STIS spectra of HD 99890 have been obtained under two separate observing programs, one of which (GO program 12191) was specifically designed to search for rare heavy elements in the ISM. Since the new high-resolution data are far superior to the spectrum analyzed by R11 (in terms of total exposure time and overall data quality), we redetermined column densities for this sight line using only the high-resolution data.

There are 30 additional sight lines not included in our primary sample—because they showed no sign of absorption from As ii, Cd ii, Sn ii, or Pb ii and had not been analyzed previously by R11—that have published Ge ii and/or Kr i column densities from STIS observations (Cartledge et al. 2001, 2003, 2006, 2008; Welty 2007). There are another 19 sight lines with published column densities for Ga ii, Ge ii, As ii, Kr i, Cd ii, Sn ii, and/or Pb ii from GHRS observations (Savage et al. 1992; Cardelli et al. 1993; Hobbs et al. 1993; Cardelli 1994; Welty et al. 1995, 1999; Cardelli & Meyer 1997; Sofia et al. 1999; Federman et al. 2003; Cartledge et al. 2008). All of these sight lines are included in the analysis described in Section 4, where we evaluate the depletion characteristics of the various elements, though we do not rederive any column densities in these directions. We do apply corrections to the column densities to account for any differences in the assumed f-values between the literature studies and our investigation (see Section 3.1 and Appendix A). When combined with our primary sample, this extended sample of sight lines with column density measurements from the literature brings the total number of sight lines considered in this investigation to 128. (This includes 10 additional sight lines with previously published column densities of O i only. These directions were added to our survey so that our sample for oxygen would be as complete as possible, just as for the other elements.)

Table 1 provides the relevant data for the 69 O and B-type stars that served as background targets for our primary sample of interstellar sight lines. Many of these stars were included in the investigation of element depletions by J09, who carefully compiled spectral types for the stars in his survey (and gives references to the original sources). From those spectral types, J09 determined distances and reddenings to his targets following a rigorous process based on spectroscopic parallax that was originally implemented by Bowen et al. (2008, hereafter B08) in their survey of O vi absorption in the Galactic disk. In general, for any of the stars in our sample that were analyzed by J09 or B08, we adopt the same spectral types, distances, and reddenings given in those references. For stars not included in either investigation, we compute the distances and reddenings using the same set of procedures that those studies invoked, adopting intrinsic colors from Wegner (1994) and absolute visual magnitudes from B08 (see Appendix  B of B08 for a detailed description of the method and its associated caveats). References to the sources of the chosen spectral types for these stars are given in Table 1. An exception to this general approach to obtaining distances to our targets is that if a star has an Hipparcos parallax measurement that is significant at the 4σ level or greater (based on the second reduction of Hipparcos data; van Leeuwen 2007), we adopt the Hipparcos distance to that star. (J09 had an acceptance threshold for Hipparcos results of 10σ, while B08 had a threshold of 5σ.)

The Galactic coordinates and V magnitudes listed in Table 1 were obtained from the SIMBAD database. We note, however, that these V magnitudes are not necessarily the same as those used to determine the distances and reddenings for some stars, since we follow the recommendation of B08 in using magnitudes from the Tycho Starmapper catalog (ESA 1997)⁴ to obtain values for B and V, after applying the appropriate transformation to the Tycho magnitudes B_T and V_T (see Appendix B1 of B08). We did use the SIMBAD values of B and V for one of our stars (CPD−30 5410), as this star is not listed in the Tycho catalog. Another one of our stars (HD 203338) has a composite spectrum, with both a hot (B1 V) component and a cool (M1 Ibep) component (Simonson 1968), making a determination of the distance and reddening for this sight line challenging. Fortunately, the Hipparcos catalog lists values of B_T and V_T separately for the two components,⁵ allowing us to derive an appropriate distance and reddening by focusing solely on the hot component. The results we obtain for this star, E(B − V) = 0.49 and d = 1.4 kpc, are similar to the results for other stars that (like HD 203338) are members of the Cep OB2 association, such as HD 207198, HD 207308, and HD 207538 (see Table 1). The distances and Galactic latitudes compiled for the stars in our sample were used to calculate the heights of the stars above or below the midplane of the Galaxy. These z distances are given in the last column of Table 1.

Figure 1 presents a series of histograms that illustrates some of the properties of the 128 sight lines considered in this investigation (where we have included those sight lines with column density measurements from the literature). The three panels show distributions for the total hydrogen column densities, N(H_tot) = N(H i) + 2N(H₂), the distances to the background stars, and the heights of the stars above or below the Galactic plane. (The sources of the adopted values of N(H i) and N(H₂) are discussed in Section 4.1.) The total hydrogen column densities range from log N(H_tot) ∼ 20.2 to 21.7, with a peak at approximately 21.3. The distances show a bimodal distribution reflecting the tendency for stars to be found either in the local arm of the Galaxy or in one of the two nearest spiral arms (the Sagittarius–Carina spiral arm or the Perseus arm; see also Figure 1 of R11). The z distances (or rather their absolute magnitudes) have an asymmetric distribution, peaking at approximately $\mathrm{log}\,| z| \sim 1.8$ and tapering off to about 3.5. These distributions are similar to the ones presented in J09 for the 243 sight lines included in that investigation (see Figures 2 and 3 of J09). While this similarity is not surprising, since there is a great deal of overlap between our sample and that of J09, it does suggest that our sample is large enough and diverse enough to be representative of the local Galactic ISM. As a result, the depletion parameters that we derive in Section 4 for the elements under consideration should be broadly applicable.

The relevant STIS data for our primary sample of interstellar sight lines were processed in a manner analogous to that described in Section 2.2 of R11. All high-resolution (E140H and E230H) and medium-resolution (E140M and E230M) echelle observations of our targets covering lines of interest to our survey were downloaded from the Mikulski Archive for Space Telescopes (MAST). The STIS data sets used in this investigation are listed in Table 2, which also provides exposure times and other details concerning the observations. The high-resolution gratings of the STIS FUV and NUV MAMA detectors provide spectra at resolving powers that range from R = 82,000 to 143,000, depending on the aperture. With the medium resolution gratings, resolving powers between 38,000 and 46,000 may be achieved (see, e.g., Table 2 of R11). Multiple exposures of a target acquired with the same echelle grating were co-added to improve the signal-to-noise (S/N) ratio in the final spectrum. When exposures that employed different apertures were co-added, the data were resampled at the dispersion of the lowest-resolution spectrum contributing to the sum. If a feature of interest appeared in adjacent echelle orders with sufficient continua on both sides of the line, then the overlapping portions of the two orders were averaged together (yielding an increase in the S/N ratio of approximately 40% in most cases). Typical S/N ratios for this sample range from 20 to 100 (per pixel), although some sight lines have significantly higher values. (The highest S/N ratios are seen in the STIS spectra of X Per, for which S/N ≈ 300 near 1400 Å in the final combined spectrum.)

Essential information regarding the interstellar lines of interest to this investigation is given in Table 3. (We analyze the O i λ1355 line in addition to those from n-capture elements, because this feature is useful for defining the overall component structure along a particular line of sight. We further note that the Ge ii λ1602 and Kr i λ1164 lines were analyzed only for the line of sight to X Per.) Small spectral segments centered on these lines were cut from the final co-added spectra. These segments were typically 2 Å wide, although it was occasionally necessary to choose a smaller portion of the spectrum to analyze so as to avoid a strong stellar absorption line or an unrelated interstellar feature. (In cases where adjacent echelle orders were averaged together, only the overlapping portions of the spectra were retained.) Each of the individual segments was then normalized to the continuum by fitting a low-order polynomial to regions free of interstellar absorption. We normalized all of the absorption profiles for a given line of sight concurrently so that the profiles from stronger lines, such as O i λ1355 and Ge ii λ1237, could serve as guides for properly fitting the continua around the weaker absorption features.

In most instances, the process of normalizing the continuum proceeded in a relatively straightforward manner. However, in the case of Sn ii λ1400 toward HD 137595, there are upward deviations in the intensities on either side of an apparent absorption feature, which is at a velocity close to that expected for Sn ii. An unusually high order polynomial would be required to "smooth out" the continuum surrounding this absorption feature. Upon further examination of the overlapping echelle orders that cover the Sn ii transition toward this star, we find that one of these upward deviations is quite strong in one order and not seen in the other, indicating that the feature may be a cosmic ray hit or of instrumental origin. Since we cannot be certain that the absorption feature is unaffected by these upward deviations, we report only an upper limit on the column density of Sn ii toward HD 137595. In the case of As ii λ1263 toward CPD−59 2603, a high negative velocity component of Si ii* λ1264 overlaps with the expected position of the As ii line, preventing us from deriving even an upper limit on the column density of As ii in this direction. Finally, while there are medium-resolution (E230M) data that cover the Cd ii λλ2145, 2265 lines toward 40 Per, strong and relatively narrow stellar features prevent us from obtaining a reliable Cd ii column density (or upper limit) for this sight line.

Oscillator strengths for the transitions relevant to our investigation were generally obtained from the compilations of Morton (2000, 2003), with a few notable exceptions (see Table 3). Heidarian et al. (2015) recently reported the first experimentally determined oscillator strengths for the Pb ii transitions at 1203.6 Å and 1433.9 Å. Their results, from beam-foil spectroscopy, indicate f-values of 0.75 ± 0.03 and 0.321 ± 0.034 for Pb ii λ1203 and λ1433, respectively. Previous studies of interstellar Pb ii abundances (e.g., Welty et al. 1995) relied on theoretical determinations of the oscillator strength of the Pb ii λ1433 transition (Migdalek 1976; Cardelli et al. 1993), which Morton (2000) gives as 0.869. The new experimental f-value for Pb ii λ1433 provided by Heidarian et al. (2015), which we adopt here, is lower than the theoretical value by almost a factor of three, yielding an increase in the Pb ii column density derived from the λ1433 line of 0.43 dex.

The oscillator strength for the Ge ii transition at 1237.1 Å had likewise not been determined experimentally until recently. Heidarian et al. (2017), again using beam-foil spectroscopy, report an f-value for Ge ii λ1237 of 0.872 ± 0.113. Early studies of gas-phase Ge ii abundances in the ISM (e.g., Savage et al. 1992; Hobbs et al. 1993) relied on the oscillator strength given in Morton (1991) for the Ge ii λ1237 transition.⁶ Later studies of interstellar Ge ii (e.g., Welty et al. 1999; Cartledge et al. 2006) adopted the theoretical f-value for the λ1237 transition calculated by Biémont et al. (1998) as 1.23. This is also the value listed by Morton (2000) for this transition. The new experimental f-value for Ge ii λ1237 reported by Heidarian et al. (2017), and adopted in this work, is in better agreement with the earlier theoretical value given in Morton (1991). (While the f-value for the Ge ii transition at 1602.5 Å has not been determined experimentally, the column density we obtain from this line toward X Per agrees with the value we derive from the λ1237 line at the 10% level.)

The only other n-capture element transition listed in Table 3 that does not have an experimentally determined f-value is As ii λ1263. However, for this transition, most theoretical determinations agree with the value calculated by Biémont et al. (1998), and adopted by Morton (2000), at the 10%–20% level (e.g., Bieron et al. 1991; Cardelli et al. 1993; Brage & Leckrone 1995). Nevertheless, an experimental confirmation of the oscillator strength for As ii λ1263 would be useful.

Column densities were derived through multi-component profile synthesis fits to the normalized spectra, using the code ISMOD (see Sheffer et al. 2008). The profile fitting routine treats the column densities, b-values, and velocities of the individual components as free parameters, while minimizing the rms of the fit residuals. For a given sight line, we started by analyzing the O i λ1355 profile so that we could develop a basic understanding of the component structure in that direction. Many of the sight lines in our primary sample already had detailed O i (and Ga ii) component structures from R11. For the others, we sought to produce similarly high quality component decompositions following the same basic procedures as in R11. In most cases, direct fits to the O i λ1355 profiles yielded good constraints on the velocities and b-values of the individual components, particularly when high-resolution (E140H) data were being analyzed. When analyzing medium-resolution (E140M) spectra, it was occasionally necessary to impose certain restrictions on the fits, such as requiring the b-values to fall within a particular range, as determined either directly from the data or from other species observed at higher resolution.⁷

Once a suitable component decomposition of the O i λ1355 profile was in hand, we proceeded to fit the profiles of the other species of interest that were available for that particular sight line. We began by adopting the O i component structure (i.e., the fractional column densities, relative velocities, and b-values of the O i components) as input parameters to the profile fitting routine, allowing all of the parameters to vary freely. However, due to the weakness of many of the lines of interest (particularly those of As ii, Sn ii, and Pb ii), it was often necessary to constrain the fits in some way so as to achieve realistic results while mitigating the effects of noise in the profiles. In these cases, depending on the quality of the data, we would either fix the relative velocities of the components, allowing the individual column densities and b-values to vary, or we would fix the fractional column densities, relative velocities, and b-values, allowing only the total column density and the absolute velocity of the profile template to vary freely. When multiple absorption complexes were evident in the profile, a template was created for each complex and fitted to that portion of the profile independently. A similar approach was adopted by R11, who demonstrated the reliability and effectiveness of using profile templates to fit weak interstellar features. For the present results, one can judge the degree to which the templates match the observed spectra by examining the examples presented in Figures 2–17. (In Table 4, we present the final component structures obtained for O i, Ga ii, and Ge ii for sight lines not analyzed by R11. The table also includes component results for HD 99890 derived from high-resolution spectra newly analyzed in this work.)

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Table 5 presents the total (line-of-sight) column densities of O i, Ga ii, Ge ii, As ii, Kr i, Cd ii, Sn ii, and Pb ii for the 69 sight lines in our primary sample. (A compilation of column density measurements from the literature for an additional 59 sight lines with STIS or GHRS data is presented in Appendix A.) Uncertainties in total column density for the sight lines in our primary sample were calculated as the quadrature sums of the uncertainties in the column densities of the individual components contributing to the absorption profiles. For the individual components, the column density uncertainties are proportional to the corresponding equivalent width uncertainties, which are based on the widths of the components (i.e., the full widths at half maximum) and the rms variations in the continua surrounding the profiles. This approach of basing the column density uncertainties on equivalent width uncertainties is justified, since the majority of absorption lines in our survey fall on the linear portion of the curve of growth. The Ge ii λ1237 lines, however, are stronger than any of the other lines we examine, and may be somewhat saturated in many cases. We therefore added (in quadrature) an extra amount of uncertainty to the error for Ge ii based on an estimate of the degree of saturation in the line profile. To estimate the degree of saturation, we considered the difference between the fitted column density and the column density one would obtain under the assumption that the line is optically thin. Our method is equivalent to varying the effective b-value by about 10% using a traditional curve-of-growth analysis. (This process increased the uncertainty in the Ge ii column density by only 0.01 dex, on average. However, for the more heavily saturated sight lines, the increase in uncertainty was as high as 0.04 dex.) For all nondetections, and cases where the derived column density was less than twice the calculated uncertainty, we determined 3σ upper limits by calculating what the error in column density would be if the undetected line had a component structure identical to that of O i λ1355.

Table 5.  Column Densities

Star	log N(O i)	log N(Ga ii)	log N(Ge ii)	log N(As ii)	log N(Kr i)	log N(Cd ii)	log N(Sn ii)	log N(Pb ii)
HD 1383	${18.15}_{-0.02}^{+0.02}$ a	${12.07}_{-0.05}^{+0.05}$	${12.74}_{-0.02}^{+0.02}$ a	<12.10	${12.52}_{-0.09}^{+0.08}$ a	⋯	${11.88}_{-0.17}^{+0.12}$	<12.17
HD 13268	${18.04}_{-0.06}^{+0.05}$	${11.58}_{-0.13}^{+0.10}$	${12.71}_{-0.06}^{+0.05}$	<12.37	<13.00	⋯	<11.76	<12.10
HD 13745	${17.97}_{-0.06}^{+0.06}$	${11.76}_{-0.07}^{+0.06}$	${12.60}_{-0.06}^{+0.05}$	<12.34	<13.07	⋯	<11.76	<12.08
HD 14434	${18.18}_{-0.06}^{+0.05}$	${11.94}_{-0.07}^{+0.06}$	${12.88}_{-0.08}^{+0.07}$	<12.45	<13.32	⋯	<11.75	<12.13
HD 22951	${17.75}_{-0.01}^{+0.01}$	${11.20}_{-0.03}^{+0.02}$	⋯	⋯	⋯	⋯	${11.05}_{-0.03}^{+0.03}$	$\lt 11.00$
HD 23180	${17.75}_{-0.01}^{+0.01}$	${11.10}_{-0.04}^{+0.04}$	⋯	⋯	⋯	⋯	${11.14}_{-0.02}^{+0.02}$	${11.27}_{-0.10}^{+0.08}$
HD 24190	${17.86}_{-0.03}^{+0.03}$	${11.34}_{-0.06}^{+0.05}$	${12.31}_{-0.03}^{+0.03}$	${11.55}_{-0.14}^{+0.11}$	${12.27}_{-0.03}^{+0.03}$	⋯	<11.13	${11.33}_{-0.24}^{+0.16}$ b
HD 24398	${17.78}_{-0.01}^{+0.01}$	${11.23}_{-0.02}^{+0.02}$	⋯	⋯	⋯	⋯	${11.16}_{-0.04}^{+0.03}$	${11.21}_{-0.10}^{+0.08}$
HD 24534	${17.886}_{-0.004}^{+0.003}$	${11.21}_{-0.01}^{+0.01}$	${12.33}_{-0.04}^{+0.04}$ c	${11.38}_{-0.07}^{+0.06}$	${12.40}_{-0.08}^{+0.07}$ d	${11.10}_{-0.04}^{+0.03}$ e	${11.17}_{-0.01}^{+0.01}$	${11.13}_{-0.07}^{+0.06}$
HD 27778	${17.81}_{-0.02}^{+0.02}$	⋯	${12.23}_{-0.03}^{+0.03}$	<11.73	${12.28}_{-0.04}^{+0.04}$	${11.10}_{-0.07}^{+0.06}$ e	⋯	⋯
HD 36841	${17.64}_{-0.08}^{+0.07}$	${11.06}_{-0.22}^{+0.14}$	${12.01}_{-0.08}^{+0.07}$	<12.03	<12.35	⋯	<11.38	<11.80
HD 37021	${18.14}_{-0.02}^{+0.02}$	⋯	${12.51}_{-0.05}^{+0.05}$	${11.58}_{-0.23}^{+0.15}$	${12.64}_{-0.04}^{+0.03}$	${11.08}_{-0.13}^{+0.10}$ e	⋯	⋯
HD 37061	${18.28}_{-0.01}^{+0.01}$	⋯	${12.55}_{-0.05}^{+0.05}$	${11.85}_{-0.05}^{+0.05}$	${12.72}_{-0.01}^{+0.01}$	${11.35}_{-0.03}^{+0.02}$ e	⋯	⋯
HD 43818	${18.21}_{-0.02}^{+0.02}$	⋯	${12.80}_{-0.07}^{+0.06}$	<12.18	${12.76}_{-0.17}^{+0.12}$	⋯	⋯	⋯
HD 52266	${18.00}_{-0.03}^{+0.03}$	⋯	${12.50}_{-0.04}^{+0.03}$	<11.49	${12.16}_{-0.08}^{+0.06}$	⋯	⋯	${11.47}_{-0.23}^{+0.15}$ b
HD 69106	${17.51}_{-0.03}^{+0.03}$	⋯	${12.27}_{-0.02}^{+0.02}$	<11.36	${12.21}_{-0.04}^{+0.03}$	⋯	⋯	${11.10}_{-0.19}^{+0.13}$ b
HD 79186	${17.93}_{-0.03}^{+0.03}$	⋯	${12.54}_{-0.05}^{+0.04}$	$\lt 12.17$	${12.41}_{-0.08}^{+0.07}$	⋯	⋯	⋯
HD 88115	${17.76}_{-0.04}^{+0.04}$ a	${11.66}_{-0.11}^{+0.09}$	${12.26}_{-0.04}^{+0.04}$ a	$\lt 12.04$	${12.19}_{-0.17}^{+0.12}$	⋯	<11.97	<12.07
HD 92554	${18.00}_{-0.08}^{+0.07}$	${11.77}_{-0.08}^{+0.07}$	${12.65}_{-0.05}^{+0.05}$	<12.33	<12.71	⋯	<11.86	<12.19
HD 93205	${18.06}_{-0.03}^{+0.03}$	${11.84}_{-0.05}^{+0.04}$	${12.59}_{-0.03}^{+0.03}$	<12.13	${12.40}_{-0.17}^{+0.12}$	⋯	${11.30}_{-0.21}^{+0.14}$	<11.81
HD 93222	${18.12}_{-0.02}^{+0.02}$	${11.86}_{-0.04}^{+0.04}$	${12.73}_{-0.03}^{+0.03}$	<12.10	${12.34}_{-0.15}^{+0.11}$	⋯	${11.72}_{-0.06}^{+0.05}$	<11.77
HD 93237	${17.16}_{-0.05}^{+0.05}$	${10.70}_{-0.08}^{+0.07}$	${11.73}_{-0.04}^{+0.03}$	<11.57	<11.52	⋯	${11.01}_{-0.07}^{+0.06}$	<11.18
HD 99872	${17.78}_{-0.03}^{+0.03}$	${11.48}_{-0.03}^{+0.03}$	${12.33}_{-0.04}^{+0.04}$	<11.56	${12.29}_{-0.04}^{+0.03}$	⋯	${11.12}_{-0.12}^{+0.09}$	<11.46
HD 99890	${17.77}_{-0.01}^{+0.01}$	${11.48}_{-0.03}^{+0.02}$	${12.38}_{-0.02}^{+0.02}$	<11.47	${12.03}_{-0.08}^{+0.07}$	<10.99	${10.96}_{-0.09}^{+0.07}$	<11.20
HD 104705	${17.88}_{-0.03}^{+0.03}$	${11.58}_{-0.02}^{+0.02}$	${12.43}_{-0.03}^{+0.03}$	${11.88}_{-0.25}^{+0.16}$	${12.23}_{-0.14}^{+0.11}$	⋯	${11.37}_{-0.06}^{+0.06}$	<11.47
HD 108002	${17.81}_{-0.05}^{+0.05}$	${11.55}_{-0.05}^{+0.05}$	${12.42}_{-0.04}^{+0.04}$	<12.12	<12.26	⋯	${11.55}_{-0.19}^{+0.13}$	<11.72
HD 108639	${18.03}_{-0.03}^{+0.03}$	${11.79}_{-0.02}^{+0.02}$	${12.64}_{-0.02}^{+0.02}$	<11.63	${12.42}_{-0.04}^{+0.04}$	⋯	${11.40}_{-0.11}^{+0.09}$	<11.61
HD 110434	${17.57}_{-0.05}^{+0.04}$	${11.33}_{-0.07}^{+0.06}$	${12.12}_{-0.05}^{+0.04}$	<11.92	<11.89	⋯	<11.08	<11.64
HD 111934	${17.95}_{-0.04}^{+0.03}$	⋯	${12.65}_{-0.04}^{+0.04}$	<12.15	<12.25	⋯	⋯	⋯
HD 114441	${17.93}_{-0.07}^{+0.06}$	${11.68}_{-0.10}^{+0.08}$	${12.50}_{-0.05}^{+0.04}$	<12.27	<12.56	⋯	<11.81	<12.01
HD 114886	${17.97}_{-0.03}^{+0.03}$	${11.74}_{-0.03}^{+0.03}$	${12.56}_{-0.04}^{+0.03}$	<12.00	${12.43}_{-0.13}^{+0.10}$	⋯	${11.27}_{-0.14}^{+0.11}$	<11.65
HD 116781	${18.00}_{-0.04}^{+0.03}$	⋯	${12.48}_{-0.04}^{+0.04}$	<12.14	${12.26}_{-0.14}^{+0.11}$	⋯	⋯	⋯
HD 121968	${17.32}_{-0.06}^{+0.05}$	${11.05}_{-0.05}^{+0.05}$	${11.82}_{-0.04}^{+0.04}$	<11.68	<11.74	⋯	<10.80	<11.30
HD 122879	${17.93}_{-0.02}^{+0.02}$	${11.58}_{-0.03}^{+0.03}$	${12.62}_{-0.03}^{+0.03}$	<11.53	${12.51}_{-0.04}^{+0.04}$	⋯	${11.40}_{-0.11}^{+0.09}$	<11.56
HD 124314	${18.19}_{-0.02}^{+0.02}$	${11.85}_{-0.04}^{+0.03}$	${12.73}_{-0.03}^{+0.03}$	<12.08	${12.68}_{-0.06}^{+0.06}$	⋯	${11.60}_{-0.10}^{+0.08}$	<11.86
HD 137595	${17.79}_{-0.03}^{+0.03}$	${11.09}_{-0.10}^{+0.08}$	${12.24}_{-0.04}^{+0.04}$	<11.77	${12.33}_{-0.08}^{+0.06}$	⋯	$\lt 10.97$	${11.33}_{-0.26}^{+0.16}$
HD 147683	${17.88}_{-0.03}^{+0.03}$	${11.38}_{-0.05}^{+0.05}$	${12.34}_{-0.04}^{+0.03}$	$\lt 12.01$	${12.45}_{-0.06}^{+0.05}$	⋯	${11.35}_{-0.07}^{+0.06}$	<11.54
HD 147888	${18.24}_{-0.01}^{+0.01}$	⋯	${12.49}_{-0.05}^{+0.05}$	${11.77}_{-0.06}^{+0.05}$	${12.71}_{-0.02}^{+0.02}$	${11.35}_{-0.03}^{+0.03}$ e	⋯	⋯
HD 147889	${17.96}_{-0.04}^{+0.04}$	${11.66}_{-0.05}^{+0.05}$	${12.54}_{-0.10}^{+0.08}$	<12.26	<12.71	<11.97	${11.52}_{-0.14}^{+0.11}$	${11.85}_{-0.17}^{+0.12}$
HD 148594	${17.91}_{-0.02}^{+0.02}$	⋯	${12.29}_{-0.05}^{+0.05}$	<11.95	${12.39}_{-0.09}^{+0.07}$	⋯	⋯	⋯
HD 148937	${18.31}_{-0.01}^{+0.01}$	${11.82}_{-0.05}^{+0.04}$	${12.87}_{-0.05}^{+0.04}$	<12.27	<12.68	⋯	<11.37	<11.82
HD 152590	${18.02}_{-0.01}^{+0.01}$ a	${11.59}_{-0.09}^{+0.08}$	${12.58}_{-0.03}^{+0.03}$ a	${11.60}_{-0.17}^{+0.12}$	${12.39}_{-0.04}^{+0.03}$ a	${11.23}_{-0.14}^{+0.11}$ e	${11.64}_{-0.13}^{+0.10}$	<11.98
HD 156110	${17.40}_{-0.07}^{+0.06}$	⋯	${11.52}_{-0.06}^{+0.05}$	<11.64	<11.69	⋯	⋯	⋯
HD 157857	${18.09}_{-0.02}^{+0.02}$	⋯	${12.55}_{-0.07}^{+0.06}$	<11.83	<12.54	⋯	⋯	⋯
HD 165246	${18.08}_{-0.01}^{+0.01}$	⋯	${12.61}_{-0.04}^{+0.04}$	<11.51	${12.47}_{-0.02}^{+0.02}$	⋯	⋯	${11.27}_{-0.20}^{+0.14}$ b
HD 165955	${17.70}_{-0.08}^{+0.06}$	${11.63}_{-0.07}^{+0.06}$	${12.44}_{-0.03}^{+0.03}$	<12.11	<12.34	⋯	<11.55	<11.94
HD 177989	${17.80}_{-0.03}^{+0.03}$	${11.29}_{-0.02}^{+0.02}$	${12.24}_{-0.02}^{+0.02}$	<11.91	${12.13}_{-0.09}^{+0.07}$	⋯	${11.00}_{-0.10}^{+0.08}$	<11.26
HD 185418	${18.05}_{-0.03}^{+0.03}$	⋯	${12.52}_{-0.04}^{+0.04}$	<11.54	${12.44}_{-0.02}^{+0.02}$	⋯	⋯	⋯
HD 187311	${17.34}_{-0.12}^{+0.09}$	<11.21	${11.54}_{-0.17}^{+0.12}$	<11.97	<12.24	⋯	<11.35	<11.82
HD 192035	${17.98}_{-0.06}^{+0.05}$	${11.58}_{-0.09}^{+0.08}$	${12.49}_{-0.04}^{+0.04}$	<12.30	<12.52	⋯	<11.62	<12.01
HD 195965	${17.78}_{-0.05}^{+0.05}$	${11.39}_{-0.05}^{+0.05}$	${12.37}_{-0.05}^{+0.05}$	<12.19	<12.22	⋯	<11.21	<11.72
HD 198478	${18.04}_{-0.02}^{+0.02}$	⋯	${12.75}_{-0.05}^{+0.05}$	$\lt 12.05$	${12.58}_{-0.07}^{+0.06}$	⋯	⋯	⋯
HD 198781	${17.72}_{-0.07}^{+0.06}$	⋯	${12.34}_{-0.03}^{+0.03}$	<11.65	${12.08}_{-0.11}^{+0.09}$	⋯	⋯	⋯
HD 203338	${17.83}_{-0.08}^{+0.07}$	${11.37}_{-0.14}^{+0.11}$	${12.48}_{-0.04}^{+0.04}$	<12.26	<12.58	<11.78	<11.62	<12.04
HD 203374	${17.99}_{-0.01}^{+0.01}$ a	${11.51}_{-0.09}^{+0.07}$	${12.56}_{-0.02}^{+0.02}$ a	<11.81	${12.47}_{-0.04}^{+0.04}$	⋯	<11.39	<11.87
HD 207198	${18.14}_{-0.02}^{+0.02}$	⋯	${12.63}_{-0.04}^{+0.03}$	<11.82	${12.56}_{-0.06}^{+0.05}$	${11.25}_{-0.08}^{+0.07}$ e	⋯	⋯
HD 207308	${17.97}_{-0.02}^{+0.02}$	${11.53}_{-0.04}^{+0.04}$	${12.50}_{-0.04}^{+0.04}$	${11.77}_{-0.27}^{+0.16}$	${12.47}_{-0.11}^{+0.09}$	⋯	${11.15}_{-0.23}^{+0.15}$	${11.72}_{-0.16}^{+0.11}$
HD 207538	${18.13}_{-0.01}^{+0.01}$	${11.57}_{-0.03}^{+0.03}$	${12.62}_{-0.04}^{+0.04}$	${11.62}_{-0.29}^{+0.17}$	${12.45}_{-0.12}^{+0.10}$	⋯	${11.56}_{-0.06}^{+0.05}$	${11.56}_{-0.17}^{+0.12}$
HD 208266	${18.06}_{-0.02}^{+0.02}$	${11.48}_{-0.05}^{+0.04}$	${12.62}_{-0.05}^{+0.05}$	<11.78	${12.47}_{-0.08}^{+0.07}$	⋯	<11.20	<11.57
HD 208947	${17.61}_{-0.04}^{+0.04}$	⋯	${12.18}_{-0.03}^{+0.03}$	<11.75	${12.00}_{-0.09}^{+0.08}$	⋯	⋯	⋯
HD 209339	${17.97}_{-0.02}^{+0.02}$	${11.49}_{-0.03}^{+0.02}$	${12.52}_{-0.03}^{+0.03}$	${11.67}_{-0.26}^{+0.16}$	${12.32}_{-0.05}^{+0.05}$	⋯	${11.40}_{-0.07}^{+0.06}$	<11.41
HD 210809	${17.95}_{-0.04}^{+0.04}$ a	${11.63}_{-0.08}^{+0.07}$	${12.47}_{-0.03}^{+0.03}$ a	<11.79	<12.40	⋯	<11.65	<12.03
HD 212791	${17.76}_{-0.05}^{+0.04}$	⋯	${12.30}_{-0.04}^{+0.03}$	<12.17	<12.13	⋯	⋯	⋯
HD 218915	${17.97}_{-0.02}^{+0.02}$	${11.51}_{-0.02}^{+0.02}$	${12.49}_{-0.03}^{+0.03}$	<11.95	${12.22}_{-0.15}^{+0.11}$	⋯	${11.22}_{-0.09}^{+0.07}$	${11.43}_{-0.15}^{+0.11}$
HDE 232522	${17.89}_{-0.02}^{+0.02}$	${11.56}_{-0.02}^{+0.02}$	${12.44}_{-0.02}^{+0.02}$	<11.75	${12.10}_{-0.08}^{+0.07}$	<11.38	${11.26}_{-0.09}^{+0.07}$	<11.52
HDE 303308	${18.11}_{-0.03}^{+0.02}$	${11.70}_{-0.04}^{+0.04}$	${12.60}_{-0.04}^{+0.04}$	<12.15	${12.44}_{-0.17}^{+0.12}$	⋯	${11.34}_{-0.17}^{+0.12}$	<11.78
HDE 308813	${18.00}_{-0.06}^{+0.05}$	${11.68}_{-0.08}^{+0.07}$	${12.51}_{-0.04}^{+0.03}$	<12.18	<12.46	⋯	<11.40	<11.94
CPD−30 5410	${17.92}_{-0.06}^{+0.05}$	${11.19}_{-0.24}^{+0.15}$	${12.35}_{-0.06}^{+0.06}$	<12.14	<12.45	<11.73	<11.53	<11.89
CPD−59 2603	${18.01}_{-0.02}^{+0.02}$ a	${11.83}_{-0.02}^{+0.02}$ a	${12.65}_{-0.02}^{+0.02}$ a	⋯f	${12.46}_{-0.09}^{+0.07}$ a	⋯	${11.42}_{-0.14}^{+0.11}$	<11.82

Notes.

^aWeighted mean of the column densities obtained from high-resolution (E140H) and medium-resolution (E140M) data. ^bColumn density obtained from the Pb ii λ1203 line. ^cWeighted mean of the column densities obtained from the Ge ii λ1237 line (from GHRS data) and the Ge ii λ1602 line (from STIS data). ^dColumn density obtained from the Kr i λ1164 line from FUSE data. ^eWeighted mean of the column densities obtained from the Cd ii λ2145 and λ2265 lines. ^fThe expected position of the As ii λ1263 line overlaps with a high-velocity component of Si ii* λ1264, precluding a detection of As ii in this direction.

A machine-readable version of the table is available.

Download table as:  DataTypeset images: 1 2

In situations where we had both high-resolution and medium-resolution spectra covering a particular absorption feature, we analyzed the two absorption profiles separately as a check on consistency. In most of these cases, the column densities derived from the high and medium-resolution profiles agree with each other at the 1σ level or better. For HD 1383 and HD 210809, the Ge ii column densities from high and medium-resolution data covering the λ1237 line agree at about the 2σ level. These small discrepancies are likely the result of differences in continuum placement, since in both cases, the absorption profiles have multiple complexes that span a large range in velocity (55 to 75 km s⁻¹), and the medium-resolution profiles have rather low S/N values (S/N ∼ 25), making it difficult to judge the proper location of the continuum. The fact that even in these more difficult cases the results agree at the 2σ level suggests that our error estimates adequately account for uncertainties due to both noise and continuum placement. We also analyzed the Cd ii λ2145 and λ2265 profiles separately (adopting the same component structure for both lines, determined either from the stronger Cd ii line or from O i λ1355). For all seven sight lines with Cd ii detections, the column densities derived from the λ2145 and λ2265 lines agree at the 1σ level or better. Final column densities in cases where both high and medium-resolution spectra yielded reliable determinations were obtained by taking the weighted mean of the two results. The same approach was used to derive final Cd ii column densities from our independent measurements of the λ2145 and λ2265 lines.

As noted earlier, many of the sight lines in our primary sample have been analyzed previously for the purposes of deriving column densities of Ge ii, Kr i, or both (e.g., Cartledge et al. 2003, 2006, 2008). A comparison between our determinations for Ge ii and Kr i for these sight lines and those from the literature is presented in Table 6. Overall, we find good agreement between the column densities we derive and those found in previous investigations, most of which relied on the same STIS data that we examine here. If we consider all of the Ge ii and Kr i comparisons together, we find that in 62% of the cases, the column densities agree at the 1σ level or better, while in 96% of the cases the determinations agree within 2σ. In only two cases do the column densities disagree by more than 2σ. One of these is the Ge ii column density toward HD 210809, which we find to be 0.24 dex lower than that given in Cartledge et al. (2006).⁸ The difference in this case does not appear to be related to any optical depth effects, since the equivalent widths disagree by approximately the same amount as the column densities. Rather, the discrepancy seems to be related to data quality issues. In the time since Cartledge et al. (2006) published their value, new high-resolution STIS spectra have been obtained for HD 210809 on two separate occasions (under GO programs 11737 and 12192). The new data, when co-added with the original spectrum, yield a factor of nine increase in exposure time for the region near Ge ii λ1237, corresponding to a factor of three decrease in the uncertainty of the Ge ii equivalent width.

Table 6.  Comparison with Previous Studies: Ge ii and Kr i

Star	log N(Ge ii)			log N(Kr i)
	This Work	Previous Result	References	This Work	Previous Result	References
HD 1383	${12.74}_{-0.02}^{+0.02}$	12.60 ± 0.09a	1	${12.52}_{-0.09}^{+0.08}$	⋯
HD 13268	${12.71}_{-0.06}^{+0.05}$	12.59 ± 0.07a	1	$\lt 13.00$	⋯
HD 24190	${12.31}_{-0.03}^{+0.03}$	⋯		${12.27}_{-0.03}^{+0.03}$	12.35 ± 0.06	2
HD 27778	${12.23}_{-0.03}^{+0.03}$	12.29 ± 0.04a	1	${12.28}_{-0.04}^{+0.04}$	12.37 ± 0.05	3
HD 37021	${12.51}_{-0.05}^{+0.05}$	12.47 ± 0.04a	1	${12.64}_{-0.04}^{+0.03}$	12.63 ± 0.04	3
HD 37061	${12.55}_{-0.05}^{+0.05}$	12.66 ± 0.05a	1	${12.72}_{-0.01}^{+0.01}$	12.72 ± 0.03	3
HD 43818	${12.80}_{-0.07}^{+0.06}$	12.73 ± 0.06a	1	${12.76}_{-0.17}^{+0.12}$	12.69 ± 0.09	4
HD 52266	${12.50}_{-0.04}^{+0.03}$	12.58 ± 0.04a	1	${12.16}_{-0.08}^{+0.06}$	⋯
HD 69106	${12.27}_{-0.02}^{+0.02}$	⋯		${12.21}_{-0.04}^{+0.03}$	12.19 ± 0.09	2
HD 79186	${12.54}_{-0.05}^{+0.04}$	12.49 ± 0.06a	1	${12.41}_{-0.08}^{+0.07}$	⋯
HD 99872	${12.33}_{-0.04}^{+0.04}$	⋯		${12.29}_{-0.04}^{+0.03}$	12.25 ± 0.07	2
HD 104705	${12.43}_{-0.03}^{+0.03}$	⋯		${12.23}_{-0.14}^{+0.11}$	12.05 ± 0.09	2
HD 108639	${12.64}_{-0.02}^{+0.02}$	⋯		${12.42}_{-0.04}^{+0.04}$	12.40 ± 0.10	2
HD 111934	${12.65}_{-0.04}^{+0.04}$	12.71 ± 0.04a	1	<12.25	⋯
HD 114886	${12.56}_{-0.04}^{+0.03}$	⋯		${12.43}_{-0.13}^{+0.10}$	12.43 ± 0.14	2
HD 122879	${12.62}_{-0.03}^{+0.03}$	12.62 ± 0.07a	1	${12.51}_{-0.04}^{+0.04}$	12.60 ± 0.13	2
HD 124314	${12.73}_{-0.03}^{+0.03}$	⋯		${12.68}_{-0.06}^{+0.06}$	12.70 ± 0.09	2
HD 137595	${12.24}_{-0.04}^{+0.04}$	⋯		${12.33}_{-0.08}^{+0.06}$	12.34 ± 0.07	2
HD 147683	${12.34}_{-0.04}^{+0.03}$	⋯		${12.45}_{-0.06}^{+0.05}$	12.52 ± 0.06	2
HD 147888	${12.49}_{-0.05}^{+0.05}$	12.63 ± 0.06a	1	${12.71}_{-0.02}^{+0.02}$	12.73 ± 0.03	3
HD 148594	${12.29}_{-0.05}^{+0.05}$	12.30 ± 0.06a	1	${12.39}_{-0.09}^{+0.07}$	⋯
HD 152590	${12.58}_{-0.03}^{+0.03}$	12.59 ± 0.05a	1	${12.39}_{-0.04}^{+0.03}$	12.54 ± 0.05	2
HD 156110	${11.52}_{-0.06}^{+0.05}$	11.52 ± 0.07a	1	$\lt 11.69$	⋯
HD 157857	${12.55}_{-0.07}^{+0.06}$	12.67 ± 0.09a	1	$\lt 12.54$	⋯
HD 165246	${12.61}_{-0.04}^{+0.04}$	⋯		${12.47}_{-0.02}^{+0.02}$	12.53 ± 0.06	2
HD 165955	${12.44}_{-0.03}^{+0.03}$	12.34 ± 0.04a	1	$\lt 12.34$	⋯
HD 177989	${12.24}_{-0.02}^{+0.02}$	⋯		${12.13}_{-0.09}^{+0.07}$	12.25 ± 0.07	2
HD 185418	${12.52}_{-0.04}^{+0.04}$	12.59 ± 0.04a	1	${12.44}_{-0.02}^{+0.02}$	12.50 ± 0.06	3
HD 192035	${12.49}_{-0.04}^{+0.04}$	12.48 ± 0.05a	1	$\lt 12.52$	⋯
HD 198478	${12.75}_{-0.05}^{+0.05}$	12.63 ± 0.04a	1	${12.58}_{-0.07}^{+0.06}$	12.50 ± 0.06	3
HD 198781	${12.34}_{-0.03}^{+0.03}$	12.35 ± 0.06a	1	${12.08}_{-0.11}^{+0.09}$	⋯
HD 203374	${12.56}_{-0.02}^{+0.02}$	⋯		${12.47}_{-0.04}^{+0.04}$	12.56 ± 0.06	2
HD 207198	${12.63}_{-0.04}^{+0.03}$	12.63 ± 0.05a	1	${12.56}_{-0.06}^{+0.05}$	12.68 ± 0.08	3
HD 208947	${12.18}_{-0.03}^{+0.03}$	⋯		${12.00}_{-0.09}^{+0.08}$	11.99 ± 0.08	2
HD 209339	${12.52}_{-0.03}^{+0.03}$	⋯		${12.32}_{-0.05}^{+0.05}$	12.35 ± 0.06	2
HD 210809	${12.47}_{-0.03}^{+0.03}$	12.71 ± 0.06a	1	$\lt 12.40$	⋯
HD 212791	${12.30}_{-0.04}^{+0.03}$	12.30 ± 0.07a	1	$\lt 12.13$	⋯
HDE 232522	${12.44}_{-0.02}^{+0.02}$	12.40 ± 0.08a	1	${12.10}_{-0.08}^{+0.07}$	⋯
HDE 303308	${12.60}_{-0.04}^{+0.04}$	⋯		${12.44}_{-0.17}^{+0.12}$	12.32 ± 0.09	2
HDE 308813	${12.51}_{-0.04}^{+0.03}$	12.52 ± 0.05a	1	$\lt 12.46$	⋯

Note.

^aRevised using the new experimental f-value for Ge ii λ1237 from Heidarian et al. (2017).

References. (1) Cartledge et al. (2006), (2) Cartledge et al. (2008), (3) Cartledge et al. (2003), (4) Cartledge et al. (2004).

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The other case in which our column density determination disagrees with a previously published value by more than 2σ is the Kr i column density toward HD 152590. Our result is 0.15 dex lower than the value listed in Cartledge et al. (2008). Here, again, the equivalent widths disagree by approximately the same amount as the column densities, indicating that the issue lies in the placement of the continuum. Indeed, as Cartledge et al. (2008) also point out, the underlying stellar spectrum of HD 152590 exhibits an unusually steep curvature in the immediate vicinity of the interstellar Kr i λ1235 feature. HD 152590 is one of two sight lines (along with HD 116852) that were previously identified by Cartledge et al. (2003) as potentially having elevated Kr abundances. That conclusion for HD 152590 was based on the Kr i column density originally published by Cartledge et al. (2001). In their subsequent work, Cartledge et al. (2008) revised their column density determination for this sight line downward by 0.17 dex after acquiring additional STIS observations of HD 152590 that substantially increased the exposure time near Kr i λ1235. With this revision, HD 152590 no longer appeared to exhibit a Kr abundance that deviated significantly from the mean interstellar value of log N(Kr)/N(H_tot) ≈ −9.0 (Cartledge et al. 2008).⁹ Our determination for Kr i toward HD 152590 further indicates that the Kr abundance is likely not enhanced in this direction.

Two other comparisons between our results and those of Cartledge et al. (2008) bear mentioning. The Kr i column densities we find toward HD 104705 and HDE 303308 are larger than the Cartledge et al. (2008) values by 0.18 dex and 0.12 dex, respectively. While these are only ∼1σ discrepancies (and thus not especially concerning), the reason for the discrepancies illustrates an important aspect of our approach to profile fitting. Both HD 104705 and HDE 303308 are extended sight lines (with path lengths of 5.0 and 3.8 kpc, respectively) that cross the Sagittarius–Carina spiral arm. The interstellar absorption profiles of moderately strong lines like O i λ1355 and Ge ii λ1237 in these directions exhibit a strong complex of absorption components near v_LSR = 0 km s⁻¹ (presumably tracing gas in the local ISM), along with weaker components at more negative velocities (which likely probe gas in the Sagittarius–Carina spiral arm). In Kr i λ1235, however, only the local ISM components are readily detectable. It appears that Cartledge et al. (2008), in their analysis of Kr i toward HD 104705 and HDE 303308, included only these readily detectable components in their profile fits. (We find essentially the same column densities if we include only these more obvious features in our fits.) However, such an approach would tend to underestimate the Kr abundance, since the total hydrogen column density applies to the entire line of sight. With our approach of fitting weak interstellar features with profile templates (constructed from the components seen in O i λ1355 in these cases), we are able to include all of the relevant line-of-sight components in our fits, even when some of those components would not be detected significantly on their own.

Since the ionization potentials for all of the neutral and singly ionized species we examine are greater than (or approximately equal to) that of neutral hydrogen, we can be reasonably well assured that the column densities we obtain for these species represent the total column densities of the elements for the lines of sight included in our survey. As demonstrated in Figure 1, none of the sight lines we examine have total hydrogen column densities below log N(H_tot) ≈ 20.0, where ionization effects begin to become important. We can thus derive the elemental abundances for these sight lines in the usual way. That is, we define the (logarithmic) abundance of element X as log (X/H) ≡ log N(X) − log N(H_tot), where N(X) refers to the column density of the element in its preferred stage of ionization for neutral diffuse gas. For most of the sight lines, we were able to calculate total hydrogen column densities from the values of N(H i) and N(H₂) listed in Table 2 of J09 (where references to the original sources of those values may also be found). For HD 148937, which was not included in J09, we obtained N(H i) from Diplas & Savage (1994) and N(H₂) from Sheffer et al. (2007). We were unable to determine values of N(H_tot) for 17 of the 69 sight lines in our primary sample, however, due to a lack of available information on H i and/or H₂. For the other 52 sight lines, we list in Table 7 the total hydrogen column densities, along with the corresponding elemental abundances based on the column density measurements presented in Table 5. Uncertainties in these quantities were determined through standard error propagation techniques. (Total hydrogen column densities for sight lines with column density measurements from the literature are provided in Appendix A.)

Table 7.  Elemental Abundances

Star	log N(Htot)a	F*a	log (O/H)	log (Ga/H)	log (Ge/H)	log (As/H)	log (Kr/H)	log (Cd/H)	log (Sn/H)	log (Pb/H)
HD 1383	${21.50}_{-0.09}^{+0.08}$	0.61 ± 0.04	$-{3.35}_{-0.10}^{+0.08}$	$-{9.44}_{-0.11}^{+0.09}$	$-{8.77}_{-0.10}^{+0.08}$	$\lt -9.41$	$-{8.99}_{-0.14}^{+0.10}$	⋯	$-{9.62}_{-0.21}^{+0.14}$	$\lt -9.33$
HD 13268	${21.42}_{-0.09}^{+0.07}$	0.51 ± 0.04	$-{3.37}_{-0.11}^{+0.09}$	$-{9.83}_{-0.17}^{+0.12}$	$-{8.71}_{-0.11}^{+0.09}$	$\lt -9.05$	$\lt -8.42$	⋯	$\lt -9.66$	$\lt -9.32$
HD 13745	${21.37}_{-0.10}^{+0.08}$	0.43 ± 0.07	$-{3.40}_{-0.12}^{+0.09}$	$-{9.61}_{-0.12}^{+0.10}$	$-{8.77}_{-0.12}^{+0.09}$	$\lt -9.04$	$\lt -8.31$	⋯	$\lt -9.62$	$\lt -9.30$
HD 14434	${21.47}_{-0.09}^{+0.07}$	0.52 ± 0.04	$-{3.29}_{-0.11}^{+0.09}$	$-{9.53}_{-0.12}^{+0.09}$	$-{8.58}_{-0.12}^{+0.10}$	$\lt -9.02$	$\lt -8.14$	⋯	$\lt -9.72$	$\lt -9.33$
HD 22951	${21.22}_{-0.10}^{+0.08}$	0.73 ± 0.05	$-{3.48}_{-0.10}^{+0.08}$	$-{10.02}_{-0.11}^{+0.09}$	⋯	⋯	⋯	⋯	$-{10.17}_{-0.11}^{+0.09}$	$\lt -10.23$
HD 23180	${21.20}_{-0.10}^{+0.08}$	0.84 ± 0.06	$-{3.45}_{-0.10}^{+0.08}$	$-{10.10}_{-0.11}^{+0.08}$	⋯	⋯	⋯	⋯	$-{10.06}_{-0.10}^{+0.08}$	$-{9.93}_{-0.15}^{+0.11}$
HD 24190	${21.30}_{-0.06}^{+0.05}$	0.63 ± 0.24	$-{3.44}_{-0.06}^{+0.06}$	$-{9.96}_{-0.08}^{+0.07}$	$-{8.99}_{-0.06}^{+0.06}$	$-{9.75}_{-0.16}^{+0.12}$	$-{9.03}_{-0.06}^{+0.06}$	⋯	$\lt -10.17$	$-{9.97}_{-0.26}^{+0.16}$
HD 24398	${21.19}_{-0.08}^{+0.06}$	0.88 ± 0.05	$-{3.41}_{-0.08}^{+0.06}$	$-{9.96}_{-0.08}^{+0.07}$	⋯	⋯	⋯	⋯	$-{10.04}_{-0.08}^{+0.07}$	$-{9.98}_{-0.13}^{+0.10}$
HD 24534	${21.34}_{-0.04}^{+0.03}$	0.90 ± 0.06	$-{3.46}_{-0.04}^{+0.03}$	$-{10.13}_{-0.04}^{+0.03}$	$-{9.01}_{-0.06}^{+0.05}$	$-{9.96}_{-0.08}^{+0.07}$	$-{8.94}_{-0.09}^{+0.08}$	$-{10.24}_{-0.05}^{+0.05}$	$-{10.17}_{-0.04}^{+0.04}$	$-{10.21}_{-0.08}^{+0.07}$
HD 27778	${21.36}_{-0.09}^{+0.08}$ b	⋯	$-{3.56}_{-0.10}^{+0.08}$	⋯	$-{9.13}_{-0.10}^{+0.08}$	$\lt -9.63$	$-{9.08}_{-0.11}^{+0.08}$	$-{10.26}_{-0.12}^{+0.10}$	⋯	⋯
HD 37021	${21.65}_{-0.19}^{+0.13}$ c	⋯	$-{3.51}_{-0.19}^{+0.13}$	⋯	$-{9.14}_{-0.20}^{+0.14}$	$-{10.07}_{-0.34}^{+0.19}$	$-{9.01}_{-0.19}^{+0.13}$	$-{10.57}_{-0.25}^{+0.16}$	⋯	⋯
HD 37061	${21.73}_{-0.11}^{+0.09}$ c	⋯	$-{3.45}_{-0.11}^{+0.09}$	⋯	$-{9.18}_{-0.13}^{+0.10}$	$-{9.88}_{-0.13}^{+0.10}$	$-{9.01}_{-0.11}^{+0.09}$	$-{10.38}_{-0.12}^{+0.09}$	⋯	⋯
HD 69106	${21.09}_{-0.06}^{+0.06}$	0.64 ± 0.06	$-{3.58}_{-0.07}^{+0.06}$	⋯	$-{8.82}_{-0.07}^{+0.06}$	$\lt -9.73$	$-{8.88}_{-0.08}^{+0.06}$	⋯	⋯	$-{9.99}_{-0.21}^{+0.14}$
HD 79186	${21.41}_{-0.08}^{+0.07}$	0.69 ± 0.03	$-{3.48}_{-0.08}^{+0.07}$	⋯	$-{8.87}_{-0.10}^{+0.08}$	$\lt -9.24$	$-{9.00}_{-0.12}^{+0.09}$	⋯	⋯	⋯
HD 88115	${21.00}_{-0.09}^{+0.08}$	0.35 ± 0.45	$-{3.24}_{-0.11}^{+0.09}$	$-{9.34}_{-0.15}^{+0.11}$	$-{8.73}_{-0.10}^{+0.08}$	$\lt -8.96$	$-{8.80}_{-0.20}^{+0.14}$	⋯	$\lt -9.03$	$\lt -8.93$
HD 92554	${21.28}_{-0.13}^{+0.10}$	0.27 ± 0.07	$-{3.28}_{-0.16}^{+0.12}$	$-{9.51}_{-0.16}^{+0.12}$	$-{8.64}_{-0.14}^{+0.11}$	$\lt -8.95$	$\lt -8.57$	⋯	$\lt -9.43$	$\lt -9.10$
HD 93205	${21.40}_{-0.04}^{+0.04}$	0.40 ± 0.03	$-{3.34}_{-0.05}^{+0.05}$	$-{9.57}_{-0.07}^{+0.06}$	$-{8.81}_{-0.05}^{+0.05}$	$\lt -9.27$	$-{9.00}_{-0.18}^{+0.12}$	⋯	$-{10.11}_{-0.22}^{+0.15}$	$\lt -9.59$
HD 93222	${21.42}_{-0.07}^{+0.06}$	0.39 ± 0.04	$-{3.30}_{-0.07}^{+0.06}$	$-{9.56}_{-0.08}^{+0.07}$	$-{8.69}_{-0.07}^{+0.06}$	$\lt -9.32$	$-{9.08}_{-0.17}^{+0.12}$	⋯	$-{9.71}_{-0.09}^{+0.08}$	$\lt -9.65$
HD 99890	${20.96}_{-0.17}^{+0.12}$	0.17 ± 0.08	$-{3.19}_{-0.17}^{+0.12}$	$-{9.48}_{-0.17}^{+0.12}$	$-{8.58}_{-0.17}^{+0.12}$	$\lt -9.49$	$-{8.93}_{-0.20}^{+0.14}$	$\lt -9.97$	$-{10.00}_{-0.20}^{+0.14}$	$\lt -9.76$
HD 104705	${21.18}_{-0.08}^{+0.07}$	0.33 ± 0.05	$-{3.30}_{-0.09}^{+0.07}$	$-{9.60}_{-0.09}^{+0.07}$	$-{8.75}_{-0.09}^{+0.07}$	$-{9.29}_{-0.27}^{+0.17}$	$-{8.95}_{-0.17}^{+0.12}$	⋯	$-{9.81}_{-0.11}^{+0.09}$	$\lt -9.71$
HD 108639	${21.38}_{-0.10}^{+0.08}$	0.37 ± 0.37	$-{3.35}_{-0.11}^{+0.09}$	$-{9.59}_{-0.11}^{+0.09}$	$-{8.75}_{-0.11}^{+0.09}$	$\lt -9.76$	$-{8.97}_{-0.11}^{+0.09}$	⋯	$-{9.99}_{-0.16}^{+0.12}$	$\lt -9.77$
HD 114886	${21.40}_{-0.06}^{+0.05}$	0.87 ± 0.31	$-{3.43}_{-0.07}^{+0.06}$	$-{9.67}_{-0.07}^{+0.06}$	$-{8.84}_{-0.07}^{+0.06}$	$\lt -9.41$	$-{8.98}_{-0.15}^{+0.11}$	⋯	$-{10.14}_{-0.16}^{+0.12}$	$\lt -9.75$
HD 116781	${21.24}_{-0.11}^{+0.09}$	0.44 ± 0.07	$-{3.25}_{-0.12}^{+0.09}$	⋯	$-{8.76}_{-0.12}^{+0.09}$	$\lt -9.11$	$-{8.98}_{-0.19}^{+0.13}$	⋯	⋯	⋯
HD 121968	${20.59}_{-0.16}^{+0.12}$	0.26 ± 0.06	$-{3.27}_{-0.18}^{+0.13}$	$-{9.54}_{-0.18}^{+0.12}$	$-{8.78}_{-0.17}^{+0.12}$	$\lt -8.91$	$\lt -8.85$	⋯	$\lt -9.79$	$\lt -9.29$
HD 122879	${21.34}_{-0.14}^{+0.10}$	0.55 ± 0.04	$-{3.40}_{-0.14}^{+0.11}$	$-{9.75}_{-0.14}^{+0.11}$	$-{8.72}_{-0.14}^{+0.11}$	$\lt -9.81$	$-{8.83}_{-0.15}^{+0.11}$	⋯	$-{9.94}_{-0.18}^{+0.13}$	$\lt -9.78$
HD 124314	${21.51}_{-0.08}^{+0.07}$	0.59 ± 0.05	$-{3.32}_{-0.08}^{+0.07}$	$-{9.66}_{-0.09}^{+0.07}$	$-{8.78}_{-0.09}^{+0.07}$	$\lt -9.43$	$-{8.83}_{-0.10}^{+0.08}$	⋯	$-{9.91}_{-0.13}^{+0.10}$	$\lt -9.65$
HD 137595	${21.22}_{-0.05}^{+0.05}$	0.77 ± 0.22	$-{3.43}_{-0.06}^{+0.05}$	$-{10.13}_{-0.12}^{+0.09}$	$-{8.98}_{-0.07}^{+0.06}$	$\lt -9.45$	$-{8.89}_{-0.10}^{+0.08}$	⋯	$\lt -10.25$	$-{9.89}_{-0.28}^{+0.17}$
HD 147683	${21.41}_{-0.14}^{+0.11}$	0.56 ± 0.47	$-{3.52}_{-0.15}^{+0.11}$	$-{10.02}_{-0.16}^{+0.12}$	$-{9.07}_{-0.15}^{+0.11}$	$\lt -9.39$	$-{8.95}_{-0.16}^{+0.12}$	⋯	$-{10.06}_{-0.17}^{+0.12}$	$\lt -9.86$
HD 147888	${21.74}_{-0.13}^{+0.10}$	0.88 ± 0.06	$-{3.50}_{-0.13}^{+0.10}$	⋯	$-{9.25}_{-0.14}^{+0.11}$	$-{9.97}_{-0.15}^{+0.11}$	$-{9.03}_{-0.13}^{+0.10}$	$-{10.39}_{-0.13}^{+0.10}$	⋯	⋯
HD 148937	${21.70}_{-0.10}^{+0.08}$ d	⋯	$-{3.39}_{-0.10}^{+0.08}$	$-{9.88}_{-0.11}^{+0.09}$	$-{8.83}_{-0.12}^{+0.09}$	$\lt -9.43$	$\lt -9.02$	⋯	$\lt -10.33$	$\lt -9.88$
HD 152590	${21.47}_{-0.06}^{+0.05}$	0.69 ± 0.03	$-{3.45}_{-0.06}^{+0.05}$	$-{9.87}_{-0.11}^{+0.09}$	$-{8.89}_{-0.06}^{+0.06}$	$-{9.87}_{-0.18}^{+0.13}$	$-{9.08}_{-0.07}^{+0.06}$	$-{10.23}_{-0.16}^{+0.11}$	$-{9.83}_{-0.15}^{+0.11}$	$\lt -9.49$
HD 157857	${21.44}_{-0.08}^{+0.07}$	0.62 ± 0.04	$-{3.35}_{-0.09}^{+0.07}$	⋯	$-{8.90}_{-0.11}^{+0.09}$	$\lt -9.61$	$\lt -8.90$	⋯	⋯	⋯
HD 165246	${21.46}_{-0.08}^{+0.06}$	0.93 ± 0.45	$-{3.38}_{-0.08}^{+0.06}$	⋯	$-{8.85}_{-0.09}^{+0.07}$	$\lt -9.95$	$-{8.99}_{-0.08}^{+0.07}$	⋯	⋯	$-{10.19}_{-0.23}^{+0.15}$
HD 165955	${21.10}_{-0.07}^{+0.06}$	0.42 ± 0.04	$-{3.40}_{-0.11}^{+0.09}$	$-{9.47}_{-0.11}^{+0.09}$	$-{8.66}_{-0.08}^{+0.07}$	$\lt -8.99$	$\lt -8.76$	⋯	$\lt -9.55$	$\lt -9.16$
HD 177989	${21.08}_{-0.07}^{+0.06}$	0.55 ± 0.05	$-{3.28}_{-0.08}^{+0.07}$	$-{9.80}_{-0.08}^{+0.07}$	$-{8.84}_{-0.08}^{+0.07}$	$\lt -9.17$	$-{8.95}_{-0.12}^{+0.09}$	⋯	$-{10.09}_{-0.13}^{+0.10}$	$\lt -9.82$
HD 185418	${21.41}_{-0.09}^{+0.07}$	0.79 ± 0.03	$-{3.36}_{-0.10}^{+0.08}$	⋯	$-{8.89}_{-0.10}^{+0.08}$	$\lt -9.87$	$-{8.97}_{-0.09}^{+0.08}$	⋯	⋯	⋯
HD 192035	${21.38}_{-0.08}^{+0.07}$	0.76 ± 0.04	$-{3.41}_{-0.10}^{+0.08}$	$-{9.81}_{-0.13}^{+0.10}$	$-{8.89}_{-0.09}^{+0.07}$	$\lt -9.08$	$\lt -8.87$	⋯	$\lt -9.76$	$\lt -9.37$
HD 195965	${21.13}_{-0.02}^{+0.02}$	0.52 ± 0.02	$-{3.36}_{-0.06}^{+0.05}$	$-{9.75}_{-0.06}^{+0.05}$	$-{8.76}_{-0.06}^{+0.05}$	$\lt -8.94$	$\lt -8.91$	⋯	$\lt -9.92$	$\lt -9.42$
HD 198478	${21.55}_{-0.15}^{+0.11}$	0.81 ± 0.05	$-{3.51}_{-0.15}^{+0.11}$	⋯	$-{8.80}_{-0.16}^{+0.12}$	$\lt -9.50$	$-{8.97}_{-0.18}^{+0.13}$	⋯	⋯	⋯
HD 198781	${21.15}_{-0.07}^{+0.06}$	0.59 ± 0.03	$-{3.43}_{-0.10}^{+0.08}$	⋯	$-{8.82}_{-0.08}^{+0.07}$	$\lt -9.50$	$-{9.07}_{-0.14}^{+0.10}$	⋯	⋯	⋯
HD 203374	${21.33}_{-0.09}^{+0.07}$	0.56 ± 0.06	$-{3.34}_{-0.09}^{+0.07}$	$-{9.82}_{-0.13}^{+0.10}$	$-{8.77}_{-0.09}^{+0.08}$	$\lt -9.52$	$-{8.86}_{-0.10}^{+0.08}$	⋯	$\lt -9.94$	$\lt -9.47$
HD 207198	${21.68}_{-0.06}^{+0.05}$	0.90 ± 0.03	$-{3.53}_{-0.06}^{+0.06}$	⋯	$-{9.04}_{-0.07}^{+0.06}$	$\lt -9.85$	$-{9.11}_{-0.08}^{+0.07}$	$-{10.43}_{-0.11}^{+0.09}$	⋯	⋯
HD 207308	${21.44}_{-0.07}^{+0.06}$	0.80 ± 0.06	$-{3.47}_{-0.08}^{+0.07}$	$-{9.90}_{-0.09}^{+0.07}$	$-{8.94}_{-0.09}^{+0.07}$	$-{9.67}_{-0.29}^{+0.17}$	$-{8.96}_{-0.14}^{+0.10}$	⋯	$-{10.29}_{-0.25}^{+0.16}$	$-{9.71}_{-0.18}^{+0.13}$
HD 207538	${21.58}_{-0.09}^{+0.08}$	0.84 ± 0.07	$-{3.45}_{-0.09}^{+0.08}$	$-{10.01}_{-0.10}^{+0.08}$	$-{8.96}_{-0.11}^{+0.09}$	$-{9.96}_{-0.32}^{+0.18}$	$-{9.13}_{-0.16}^{+0.12}$	⋯	$-{10.02}_{-0.11}^{+0.09}$	$-{10.02}_{-0.21}^{+0.14}$
HD 209339	${21.26}_{-0.07}^{+0.06}$	0.58 ± 0.04	$-{3.29}_{-0.07}^{+0.06}$	$-{9.77}_{-0.07}^{+0.06}$	$-{8.74}_{-0.08}^{+0.06}$	$-{9.60}_{-0.28}^{+0.17}$	$-{8.94}_{-0.09}^{+0.08}$	⋯	$-{9.86}_{-0.10}^{+0.08}$	$\lt -9.85$
HD 210809	${21.33}_{-0.10}^{+0.08}$	0.41 ± 0.04	$-{3.38}_{-0.11}^{+0.09}$	$-{9.70}_{-0.13}^{+0.10}$	$-{8.86}_{-0.11}^{+0.09}$	$\lt -9.54$	$\lt -8.94$	⋯	$\lt -9.69$	$\lt -9.30$
HD 212791	${21.13}_{-0.16}^{+0.12}$	0.57 ± 0.08	$-{3.37}_{-0.17}^{+0.12}$	⋯	$-{8.82}_{-0.16}^{+0.12}$	$\lt -8.95$	$\lt -9.00$	⋯	⋯	⋯
HD 218915	${21.25}_{-0.04}^{+0.03}$	0.70 ± 0.08	$-{3.29}_{-0.04}^{+0.04}$	$-{9.74}_{-0.04}^{+0.04}$	$-{8.77}_{-0.05}^{+0.04}$	$\lt -9.30$	$-{9.03}_{-0.16}^{+0.12}$	⋯	$-{10.04}_{-0.10}^{+0.08}$	$-{9.83}_{-0.16}^{+0.12}$
HDE 232522	${21.19}_{-0.06}^{+0.05}$	0.44 ± 0.03	$-{3.29}_{-0.06}^{+0.05}$	$-{9.63}_{-0.06}^{+0.06}$	$-{8.74}_{-0.06}^{+0.05}$	$\lt -9.43$	$-{9.09}_{-0.10}^{+0.08}$	$\lt -9.80$	$-{9.92}_{-0.11}^{+0.09}$	$\lt -9.66$
HDE 303308	${21.48}_{-0.07}^{+0.06}$	0.38 ± 0.04	$-{3.37}_{-0.08}^{+0.07}$	$-{9.78}_{-0.08}^{+0.07}$	$-{8.88}_{-0.08}^{+0.07}$	$\lt -9.33$	$-{9.04}_{-0.19}^{+0.13}$	⋯	$-{10.14}_{-0.19}^{+0.13}$	$\lt -9.70$
HDE 308813	${21.29}_{-0.09}^{+0.08}$	0.49 ± 0.04	$-{3.29}_{-0.12}^{+0.09}$	$-{9.61}_{-0.13}^{+0.10}$	$-{8.78}_{-0.10}^{+0.08}$	$\lt -9.11$	$\lt -8.83$	⋯	$\lt -9.89$	$\lt -9.35$
CPD−59 2603	${21.50}_{-0.08}^{+0.06}$ e	0.43 ± 0.05e	$-{3.49}_{-0.08}^{+0.07}$	$-{9.67}_{-0.08}^{+0.07}$	$-{8.85}_{-0.08}^{+0.07}$	⋯	$-{9.04}_{-0.12}^{+0.09}$	⋯	$-{10.08}_{-0.17}^{+0.12}$	$\lt -9.68$

Notes.

^aTotal hydrogen column densities were calculated from the values of N(H i) and N(H₂) listed in J09, unless otherwise noted. The line-of-sight depletion factors F_* are the observed values from J09. ^bThe large correction for stellar Lyα contamination applied to N(H i) for this star by J09 may not be necessary. Here we adopt the uncorrected value of N(H i) from Cartledge et al. (2004). This sight line is not used in the depletion analysis. ^cMeasurement of N(H₂) is not available. However, the weak or absent absorption from Cl i λ1347 indicates that there is very little H₂ in the line of sight, and we adopt N(H i) (from J09) as representative of N(H_tot). The sight line is not included in the depletion analysis. ^dThis star is not listed in J09; the total hydrogen column density was calculated using N(H i) from Diplas & Savage (1994) and N(H₂) from Sheffer et al. (2007). ^eThe value of N(H i) for this star is listed incorrectly in J09. Here, we adopt the correct value from Diplas & Savage (1994), and provide an updated value for the sight-line depletion factor F_* (E. Jenkins 2012, private communication).

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