From the Pa Beta and Br Gamma observations of a sample of T Tauri stars one concludes that blueshifted absorptions in the profiles of those lines are very rare. Only 1 star shows a blueshifted absorption at Pa Beta of the 41 observed to have this line in emission while of the 29 displaying Br Gamma in emission none has a blueshifted absorption. The most common profiles are of Type I (54% at Pa Beta and 73% at Br Gamma). IPC line profiles constitute 34% of the Pa Beta profiles and 20% of the Br Gamma profiles.
The Pa Beta and Br Gamma lines are very wide (FWHM 
km/s),
slightly blueshifted and with line wings extending to 
km/s
in the blue and to 
km/s in
the red. The Asymmetry Factor
is slightly larger than one for most cases, with the Br Gamma distribution
for this parameter showing a larger spread than that of the Pa Beta
distribution. The former also displays larger Af's than the
latter. A significant number of IPC Br Gamma lines are displaced to the blue
by about 50 km/s relative to the IPC Pa Beta lines.
A comparison between the data presented here and the existing models for the formation of the hydrogen lines favors those dealing with an accretion scenario, although there are some problems when a more quantitative comparison is done. It is not clear whether Type I profiles can be formed in a wind or not. Continuous wind models tend to produce lines with normal P Cygni profiles but Pa Beta or Br Gamma calculations are seldom found in the literature. Stochastic wind models might be able to produce profiles similar to Type I but there are no specific predictions for the Pa Beta and Br Gamma lines. The shape of the Type I line profiles, which have a slightly blueshifted emission peak, are centrally peaked and are asymmetric with slightly more emission in the blue, favour models that use accretion flows to explain the origin of the emission lines. The redshifted absorption feature in the Pa Beta and Br Gamma IPC profiles must be formed in infalling material. It is located at velocities of the order of the free-fall velocity for a typical T Tauri star. There seems to be a trend associating the amount of emission seen in the emission profiles with IPC and the determined accretion rates, suggesting the whole line structure of IPC line profiles arises in infalling material.
Based on inclinations obtained from the literature, a difference between those of the stars displaying Type I profiles and those of the stars displaying IPC is not apparent. The line profiles observed for stars that belong to a binary/multiple system do not show any preference for a given type of line profile. The distribution of types of profiles is not too different from that obtained with all line profiles.
The Pa Beta and Br Gamma lines are observed to be variable in some stars. A variability study cannot be pursued with this data set though.
As mentioned above, model line profiles for Pa Beta and Br Gamma are seldom available in the literature. In order to perform a better comparison model calculations for these lines are needed. With this in mind, very simple wind and accretion models were set up in order to compute Pa Beta and Br Gamma line profiles. These calculations and the results obtained are discussed in the next chapter.