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    Evidence for an MHD Disk Wind via Optical Forbidden Line Spectroastrometry*

    Whelan, E. T. and Pascucci, I. and Gorti, U. and Edwards, S. and Alexander, R. D. and Sterzik, M. F. and Melo, C. (2021) Evidence for an MHD Disk Wind via Optical Forbidden Line Spectroastrometry*. The Astrophysical Journal, 913 (1). p. 43. ISSN 0004-637X

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    Spectroastrometry is used to investigate the low-velocity component (LVC) of the optical forbidden emission from the T Tauri stars RU Lupi and AS 205 N. Both stars also have high-velocity forbidden emission, which is tracing a jet. For AS 205 N, analysis reveals a complicated outflow system. For RU Lupi, the [O I] λ6300 and [S II] λλ6716,6731 LV narrow component (NC) is offset along the same position angle (PA) as the high-velocity component but with a different velocity gradient than the jet, in that displacement from the stellar position along the rotation axis is decreasing with increasing velocity. From the LVC, NC, PA, and velocity gradient, it is inferred that the NC is tracing a wide-angled magnetohydrodynamic (MHD) disk wind. A photoevaporative wind is ruled out. This is supported by a comparison with a previous spectroastrometric study of the CO fundamental line. The decrease in offset with increasing velocity is interpreted as tracing an increase in the height of the wind with increasing disk radius. This is one of the first measurements of the spatial extent of the forbidden emission line LVC NC (∼40 au, 8 au for RU Lupi in the [S II] λ6731 and [O I] λ6300 lines) and the first direct confirmation that the LVC narrow component can trace an MHD disk wind.

    Item Type: Article
    Additional Information: Cite as: Whelan, E.T., Pascucci, I., Gorti, U., Edwards, S., Alexander, R.D., Sterzik, M.F. & Melo, C. 2021, "Evidence for an MHD Disk Wind via Optical Forbidden Line Spectroastrometry", The Astrophysical journal, vol. 913, no. 1, pp. 43.
    Keywords: Emission analysis; Emission lines; Emissions; Fluid flow; Magnetohydrodynamics; T Tauri stars; Tracing; Velocity; Velocity gradient; Wind;
    Academic Unit: Faculty of Science and Engineering > Experimental Physics
    Item ID: 17615
    Identification Number:
    Depositing User: Emma Whelan
    Date Deposited: 28 Sep 2023 11:03
    Journal or Publication Title: The Astrophysical Journal
    Publisher: IOP Publishing
    Refereed: Yes
    Use Licence: This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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