Disk winds are thought to play a critical role in the evolution and dispersal of protoplanetary disks. A primary diagnostic of this physics is emission from the wind, especially in the low-velocity component of the [O I] λ6,300 line. However, the interpretation of the line is usually based on spectroscopy alone, which leads to confusion between magnetohydrodynamic winds and photoevaporative winds. Here we report that in high-resolution spectral mapping of TW Hya by the multi-unit spectroscopic explorer at the Very Large Telescope, 80% of the [O I] emission is confined to within 1 au radially from the star. A generic model of a magnetothermal wind produces [O I] emission at the base of the wind that broadly matches the flux and the observed spatial and spectral profiles. The emission at large radii is much fainter than predicted from models of photoevaporation, perhaps because the magnetothermal wind partially shields the outer disk from energetic radiation from the central star. This result calls into question the previously assessed importance of photoevaporation in disk dispersal predicted by models.
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The raw MUSE data can be taken from ESO archive under programme ID no. 0104.C-0449. The combined MUSE data used in this research are available in Figshare (https://doi.org/10.6084/m9.figshare.21906306). The reduced spectral data from other ESO facilities can be downloaded through ESO Phase III archive (https://archive.eso.org/wdb/wdb/adp/phase3_spectral/form) with programme ID nos. 074.A-9021(A), 078.A-9059(A), 079.A-9006(A), 079.A-9007(A), 079.A-9017(A), 081.A-9005(A), 081.A-9023(A), 089.A-9007(A), 0101.A-9012(A), 0102.A-9008(A), 60.A-9036(A), 075.C-0202(A), 081.C-0779(A), 082.C-0390(A), 082.C-0427(C), 65.I-0404(A), 082.C-0218(A), 089.C-0299(A) and 106.20Z8.011. The reduced Keck spectral data were downloaded from the Keck Observatory Archive (https://www2.keck.hawaii.edu/koa/public/koa.php) with programme ID nos. C179Hr, C269Hr, C199Hb, N125Hr, C186Hr, N204Hr, C189Hr, C252Hr and C247Hr. The reduced ESPaDOnS spectra were downloaded from PolarBase (http://polarbase.irap.omp.eu/).
The MUSE data are reduced with the MUSE pipeline v.2.8.5, which is publicly available. Upon request, the first author will provide code (IDL) to generate figures.
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M.F. acknowledges the science research grants from the China Manned Space Project with no. CMS-CSST-2021-B06. This research is based on observations made with ESO Telescopes under programme ID nos. 0104.C-0449, 074.A-9021(A), 078.A-9059(A), 079.A-9006(A), 079.A-9007(A), 079.A-9017(A), 081.A-9005(A), 081.A-9023(A), 089.A-9007(A), 0101.A-9012(A), 0102.A-9008(A), 60.A-9036(A), 075.C-0202(A), 081.C-0779(A), 082.C-0390(A), 082.C-0427(C), 65.I-0404(A), 082.C-0218(A), 089.C-0299(A) and 106.20Z8.011. The research made use of the Keck Observatory Archive, which is operated by the W. M. Keck Observatory and the National Aeronautics and Space Administration (NASA) Exoplanet Science Institute, under contract with NASA. We acknowledge S. E. Dahm, L. Hillenbrand, J. Carpenter, W. Borucki and G. W. Marcy for datasets that were obtained through the Keck Observatory Archive.
The authors declare no competing interests.
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a, Distribution of the [O I] λ6300 line centroids of TW Hya and. These spectra are taken with ESPaDOnS (gray color filled histogram), FEROS or HARPS (maroon line filled histogram), and UVES or HIRES (olive open histogram). The numbers of the used spectra from individual instruments are shown in the figure. b, Comparisons of the [O I] λ6300 line profiles of TW Hya. For the comparisons, the centroids of the lines have been shifted to the mean centroid (-0.8 km s−1) and the spectral resolutions have been degraded to 40000. The colors are the same as in a.
Comparisons of the observed [O I] λ6300 (a) and [Ne II] 12.81 μm (b) line profiles (cyan filled circles) with the simulated ones from the MHD wind model (golden-color filled area for disk inclinations ranging from 5∘ to 7∘). In each panel, the error bars (gray color) are 1σ uncertainties, corresponding to the 68% confidence level.
Extended Data Fig. 3 Template fits to the observed MUSE spectra near [O I] λ6300 and He Iλ6678 lines.
a, Example spectra near [O I] λ6300 (gray lines) of two exposures. In each panel, the red dashed line is the best-fit template, and the blue dash-dotted line for the best-fit template correcting for the residual. The grey color filled area marks the wavelength range within which the [O I] λ6300 line is extracted, and the grey line-filed areas mark the wavelength ranges within which the uncertainties are estimated and the fluxes are integrated to construct PSF. b, same as a, but for He I λ6678 line.
a, Error-weighted mean He I λ6678 intensity map of TW Hya. b, Two slice cuts (white lines) for He I λ6678 line map shown in a, overplotted with the PSF (dark dashed lines) near He I λ6678 line. The dotted line in each panel is the standard deviation along the slice cut. c, He I λ6678 line residual map after a subtraction of a PSF which has been normalized to line map by the peak emission. d, the signal-to-noise ratio map for the He I λ6678 line residual map shown in c. The cyan and blue lines show contours with S/N=2 and 3, respectively.
a-b, Reduced χ2 from the coarse grids of the three free parameters: α, Rin and Rout. In each panel, the reduced χ2 for each pair of two parameters is lowest one by setting the remaining parameter free. c, Reduced χ2 from the fine grid of α and Rin with Rout=61 AU. In each panel, the pentagram symbol marks the minimum reduced χ2.
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Fang, M., Wang, L., Herczeg, G.J. et al. High-resolution [O I] line spectral mapping of TW Hya supportive of a magnetothermal wind. Nat Astron 7, 905–912 (2023). https://doi.org/10.1038/s41550-023-02004-x
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