Figures 5.7 and 5.8 show the Pa Beta and Br Gamma emission lines classified as Type I.
Figure 5.7: Pa Beta Type I line
profiles. Emission lines are ordered by L/C at line peak, starting
with the strongest emission line.
Figure 5.8: Br Gamma Type I line
profiles. Emission lines are ordered by L/C at line peak, starting
with the strongest emission line.
In Figures 5.9 to 5.12 below the histograms obtained considering the Type I line profiles only are represented by solid lines. For comparison, the histograms shown in Figures 5.3 to 5.6 above, obtained taken into account all line profiles are over plotted using a dotted line.
Figure 5.9 shows the distributions of the FWHM for Pa Beta and Br Gamma.
With a mean value of 
km/s
and a median of 200 km/s, the Pa Beta histogram obtained for the FWHM
using Type I line profiles only is very
similar to the one obtained using all the profiles. One concludes the
same for the Br Gamma FWHM distribution which has a mean of 
kms/ and a median of 200 km/s.
The histograms obtained for the maximum velocities observed both in the blue and in the red wings are displayed in Figure 5.10.
The Pa Beta and Br Gamma distributions of the blue wing maximum velocity and that of the Br Gamma red wing maximum velocity for Type I profiles are very similar to those obtained with all line profiles. The histogram of the Pa Beta red wing maximum velocity considering Type I profiles is slightly shifted relative to the one computed using all the lines. The value of the median of the distribution increases from +200 km/s to +240 km/s. Such a shift towards the red is expected since the numerous Type IV R Pa Beta line profiles naturally extend to lower velocities in the red wing and therefore bias the distribution of vred to lower velocities. Type I Pa Beta line profiles are nearly symmetric at the level of the line wings, which extend to similar velocities either side of the line peak. For Br Gamma Type I line profiles there is still a significant asymmetry at the level of the line wings.
The histograms for the velocity at which the line peak occurs in Type I profiles are shown in Figure 5.11. They are very similar to those obtained considering all line profiles. It is therefore the case that Type I line profiles are blueshifted by a small amount but very seldom redshifted.
The Asymmetry Factor in Type I line profiles is slightly larger than 1 in most cases, as can be seen from Figure 5.12. The Pa Beta lines have the majority of the Af's between 1 and 2 and the Br Gamma lines have typical Af's again between 1 and 2, with about 20% of the lines with Af's near 3.
From the histograms presented above for Type I line profiles, one concludes that the bias introduced by the line profiles that display redshifted absorption in the general properties of the profiles is not very large. Type I line profiles are very wide (typical FWHM is 200 km/s) and the line wings extend to about 300 km/s in the blue wing and to about 200 km/s in the red wing. The lines are slightly blueshifted and the emission is slightly more blueward than redward of the rest velocity. These results are interpreted in Section 5.4.3.