The Pa Beta and Br Gamma line profiles obtained for the observed T Tauri stars are presented in figures 5.1 and 5.2 respectively and arranged in alphabetical order by the name of the star. For the stars for which the amount of veiling could be determined (see Chapter 4) the line profiles presented are after removal of the photospheric contribution to the spectrum.
Inspecting the line profiles one concludes that of the 49 stars observed at Pa Beta, 41 show the line in emission and of the 37 stars observed at Br Gamma , 31 show the line in emission. The stars without Pa Beta in emission are: DI Tau, DQ Tau, FN Tau, Hubble 4, LkCa 7, V773 Tau, VY Tau and ZZ Tau, of which DI Tau, Hubble 4, LkCa 7 and V773 Tau are classified as WTTS in the Herbig & Bell Catalogue [Herbig & Bell 1988]. The stars without Br Gamma in emission are: DN Tau, FP Tau, GI Tau, Hubble 4, LkCa 7 and V807 Tau of which Hubble 4 and LkCa 7 are WTTS.
From the stars observed both at Pa Beta and Br Gamma some display emission in one line but not in the other. Those with emission at Pa Beta but not at Br Gamma are DN Tau, FP Tau, GI Tau and V807 Tau. V773 Tau displays emission at Br Gamma but not at Pa Beta .
Br Gamma corresponds to a transition from level n=7 while Pa Beta corresponds to a transition from level n=5, it is possible that the excitation conditions are such that n=5 is sufficiently populated for Pa Beta to be in emission while the level n=7 is weakly populated so that no, or insignificant, emission is found at Br Gamma . It is, therefore, not surprising to find a few stars without Br Gamma in emission but with emission at Pa Beta . V773 Tau is a highly variable WTTS [Feigelson et al. 1994]. It is a binary star [Welty 1995], has radio emission [Phillips et al. 1996] and x-ray flares [Tsuboi et al. 1998]. Given its characteristics it is not unexpected to find that data taken one day apart (as the Pa Beta and Br Gamma line profiles for this star presented here) show such different characteristics, as Br Gamma in emission while no significant emission is observed at Pa Beta .
The lines that appear in emission display a variety of
profiles. Although no two profiles are the same, many show similar
properties and it is useful to separate them according to the general
shape of the line profile.
Figure 5.1: Pa Beta line profiles. Stars are presented in
alphabetical order. Spectra with error bars in each spectral point are
from the UT9410 observing run. Stars for which more than one line
profile is presented have the lines arranged by observing date.
Figure 5.2: Br Gamma line profiles. Stars are
presented in alphabetical order. Spectra with error bars in each
spectral point are from the UT9410 observing run. Stars for which more
than one line profile is presented have the lines arranged by observing
date.