Results

This summer I measured the metallic abundances in a total of 13 sightlines, four of which were in Complex C, two in the Magellanic Stream and a few HVCs and IVCs in an effort to help understand where they originated. My findings were as follows:

High Velocity Cloud Complex C with sightlines MRK279, MRK205, MRK817, MRK876 and PG1626+554

MRK817 ( ~ -110 km/s)
MRK817 showed abundances in Complex C between 0.15 and 0.30 solar. Oxygen, along with a majority of the other ions, in this sightline had abundances of around 0.3 solar whereas FeII showed a small but evident amount of depletion being around 0.2 solar.

PG1626+554 ( ~ -120 km/s)
Besides an FeII abundance close to 0.19 solar, absorption lines in this sightline were very hard to measure. Although, the few detections that were present in this sightline pointed to an overall abundance of around 0.15 solar.

MRK279 ( VLSR ~ -150 km/s)
This sightline showed metallicities between 0.50 and 0.10 solar with a majority of the ion abundances occuring around 0.15 solar. Although a number of FeII absorption lines were present in this sightline OI provided a more constrained b value and was used to fit the other ions in this sightline.

MRK876 (velocities)
This proved to be a very interestesting sightline. Besides providing a number of measurable abundances in the high velocity component which are commonly associated with Complex C, we also found evidence of a second high velocity component. In the HVC with velocity around -125 km/s there was an overall abundance of 0.18 solar; whereas the second cloud, with a velocity of around -180 km/s, had a definitive abundance of OI around 0.3 solar and a measureable abundance of SiII also around 0.3 solar.

(Top Image) HE1143-1810

(Bottom Image) MRK421

Intermediate
Velocity Clouds

MRK421 ( ~ -67 km/s)
This sightline had measureable absorption levels of ten ions with abundances between 0.15 and 0.56 solar. We found the OI abundance to be very high (0.5 solar) and approximately twice that of FeII.

PG0953+414( ~ -60 km/s)
OI and FeII had the strongest absorption lines in this sightline with abundances around 0.35 solar. In general, the other metals that were easily measured were ArI and NI with absorption levels around 0.25 solar.

HE1143-1810 (56 km/s)
This was the only positive Intermediate Velocity Cloud that was analyzed in this project. It showed abundances in FeII, OI and SiII close to solar (0.75 solar); NI had a much lower metallicity as compared to that of the Sun around 0.2 solar.

Magellanic Stream
This is a high-velocity cloud that is believed to have been tidally torn from the Small Magellanic Cloud. The sightlines used to measure the metallicities of this cloud produced few absorption lines which made it very difficult to get an accurate limit on the abundances of this cloud. It has a very high velocity.

NGC7469 ( ~ -333 km/s)
The absorption lines of this sightline were very difficult to detect; the data obtained could, at best, only provide lower limits for the metal content of the Magellanic Stream. Nonetheless, overall an abundance of greater than 0.4 solar was seen using this sightline.

NGC7714 (~ -311 km/s)
Only three types of ions were detected in this sightline, PII, ArI and FeII. Of those three, only FeII could be measured with much accuracy, it showed an abundance of 0.15 solar.

The Magellanic Stream with sightlines NGC7714 and NGC7469

Positive High Velocity Clouds with sightlines NGC5253,
PG1011-040 and ESO265-G23

Positive-velocity HVCs

ESO265-G23 (~117 km/s)
The abundances of OI and FeII were measured fairly easily using ESO265-G23. Both ions had abundances of 0.13 solar; other metals in this sightline were harder to measure but seem to be around 0.13 solar.

PG1011-040 (~ 128 km/s)
This sightline also showed a number of detected ion absorptions; OI and FeII were around 0.34 solar.

NGC5253 (~102 km/s)
A difficult sightline with few absorption lines, FeII was the easiest and most accurate abundance to determine and was found to be approximately 0.35 solar.