Evolution of the HD 163296 Jet Axis Andrew Miller1, Aisling Murphy1, Christian Schneider2, Emma Whelan1, Catherine Dougados3, Jochen Eislöffel4 1Department of Experimental Physics, Maynooth University 2Hamburger Sternwarte, University of Hamburg 3IPAG, University of Grenoble 4Thüringer Landessternwarte Tautenburg, Tautenburg, Germany Abstract HD 163296 is a Herbig Ae star which drives a bipolar knotty jet with a total length of ~6000 au. Strong evidence exists that the disk of HD 163296 harbors planets which could affect the morphology of the jet, and ‘wiggling’ models have been proposed as a method to infer the presence of companions in other stars. Using the VLT/MUSE spectrograph, we investigate the morphology and proper motions of the HD 163296 jet with the aim of searching for evidence of its planetary system. In particular, we analyze the jet width and jet axis position with distance from the star and compare to ‘wiggling’ models to explore the possibility of orbital motion or precession in the jet axis. We conclude that there is no signature of this wiggle in the jet, and our results allow us to constrain the parameters of possible companions and further assess the robustness of the wiggling jet model as a method for detecting companions. 1. Introduction ●Astrophyiscal jets are ubiquitous in young stellar objects (YSOs), and accretion/outflow connection impacts circumstellar disk and potentially planet formation (Frank et al., 2014). ●Jets display complex structures, and sometimes present ‘wiggles’ in jet trajectory: potential signature of binary companions close to jet source (Masciadri & Raga., 2002; Murphy et al., 2021). ●Strong evidence for multiple planets embedded in HD 163296 disk (Teague et al., 2018; Pinte et al., 2018), and potential periodicity of jet ejection events may suggest a close-in companion (Ellerbroek et al., 2014) ●Using MUSE observations taken in 2018, we examine jet axis of HD 163296 to seek signatures of orbital motion or jet precession, and test the applicability of jet wiggling models to the case of planetary companions. 6. References 4. Results 3. Data Analysis ●Integrated spectro-images of forbidden emission lines (FELs) extracted from MUSE data cubes, focused on primarily on Hα, [N II]λ6583, and [S II]λλ6716,6731 (See Figure 1). ●Gaussian fitting along outflow axis yields jet FWHM and axis centroid position as a function of distance from the star. Deviation of centroids from axis center are examined for ‘wiggling’ signature. ●If wiggling motion is due to precession in jet axis, the motion can be expressed in terms of jet velocity (vj), precession period (ν), and half-opening angle (β) by: ●If wiggling is due to orbital motion of the jet source, the motion can be expressed in terms of orbital velocity (vo), jet velocity, orbital radius (ro), and phase angle () by: ●Each model is first fit with only vj constrained, then fit using proposed planets as function parameters. Figure 5: Parameter space of possible companion ranges expected to produce an observable ‘wiggle’ in the jet axis. Gray hatches indicated regions excluded by the MUSE observations. The green on the left indicates companions with unde- tectable effects. The top blue and bottom teal indicate periods too long or short to be observed. Figure 3: A plot of the [S II] centroids with free-fitted orbital and precession components over-laid. The distances are deprojected from the plane of the sky with x’ = xt / cos i. Only the jet velocity is held constant. The fitted parameters suggest a 0.2 M☉ companion at 8 au for an orbital motion model, while a precession model suggests a 48 MJup companion at < 0.35 au. The largest proposed planet in the HD 163296 disk is 2 Mjup, and the closest planet is located at approximately 83 au. These observations were collected with MUSE at the Very Large Telescope on​ Cerro Paranal (Chile), operated by the European Southern Observatory (ESO), under Program ID 099.C-0214(A).​ Figure 2: Co-added centroid (to