Hα line is shown for the spectrum taken in 2010 and for the spectrum taken in 2012, position 2. Pixel 00 (2010) corresponds to the south-east position. Pixel 00 for position 2 in 2012 is located in the east. Here, actually a change in the line profile is visible: the absorption component at pixel 00 (south-east, in the 2010 dataset, and east for 2012) becomes weaker when going closer to the star (see pixel 30 at −0.6′′ in 2010 and +0.6′′ offset in 2012), whereas the emission component increases when going closer to the star. The bottom-most panel gives the residuals of the slit spectrum in 2012 (position 2) when the spectrum at +0.6′′ (pixel 30) is subtracted from the spectrum at −2.5′′ (pixel 15) distance to the central star. Here, the residuals are larger compared to the other residuals in the emission lines. This indicates that the Hα line is located on the pole of the star. Negative distances indicate directions in the south-(east) of the nebula. Positive distances indicate directions towards the north-(west).
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