are shown. These figures are adapted from . For both these sources, the PEL wings are found to be displaced in the same direction as the known jets (studied through their FELRs). This displacement is also measured within the velocity range of the jets. For example, the blue-shifted jet driven by DG Tau has a radial velocity of ^200 kms-1. The blue wing of DG Tau Pap lines is displaced to ^0.6 arcseonds at a velocity of ~ —250 km/s. This corresponds to what we see in [0I]A6300 and [SII]A6731. The DG Tau jet was already known to be bright in Ha.
Reference  also investigated the optical spectra of RU Lupi with spectro-astrometry. The Ha emission line is symmetric with no obvious outflow component. However, Gaussian fitting of the spatial profile revealed the wing emission to be displaced in the direction of the blue- and red-shifted jet. What was interesting about the results of the RU Lupi and V536 Aql analysis was that the PEL wings traced the blue- and red-shifted jets, while only the blue-shifted jets are seen in the FELs. FELRs are commonly only blue-shifted, and this is explained through the obscuration effect of the cir-cumstellar disk. Reference  explained the RU Lupi result using an idea based on circumstellar disk dust holes. As FE is quenched close to a typical CTTS (densities are too high), the FELRs occur further from the central engine than the PELs. Hence, a PELR originating in a red-shifted jet could be seen through a gap in the circumstellar disk while a red-shifted FELR would
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