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Aligned grains and scattered light found in gaps of planet-forming disk

Nature volume 623, pages 705–708 (2023)Cite this article

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Abstract

Polarized (sub)millimetre emission from dust grains in circumstellar disks was initially thought to be because of grains aligned with the magnetic field1,2. However, higher-resolution multi-wavelength observations3,4,5 and improved models6,7,8,9,10 found that this polarization is dominated by self-scattering at shorter wavelengths (for example, 870 µm) and by grains aligned with something other than magnetic fields at longer wavelengths (for example, 3 mm). Nevertheless, the polarization signal is expected to depend on the underlying substructure11,12,13, and observations until now have been unable to resolve polarization in multiple rings and gaps. HL Tau, a protoplanetary disk located 147.3 ± 0.5 pc away14, is the brightest class I or class II disk at millimetre–submillimetre wavelengths. Here we show deep, high-resolution polarization observations of HL Tau at 870  µm, resolving polarization in both the rings and the gaps. We find that the gaps have polarization angles with a notable azimuthal component and a higher polarization fraction than the rings. Our models show that the disk polarization is due to both scattering and emission from the aligned effectively prolate grains. The intrinsic polarization of aligned dust grains is probably more than 10%, which is much higher than that expected in low-resolution observations (about 1%). Asymmetries and dust features that are not seen in non-polarimetric observations are seen in the polarization observations.

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Fig. 1: The 870-µm polarization morphology overlaid on the total-intensity images of HL Tau.
Fig. 2: The 870-µm total-intensity (Stokes I) image of HL Tau.
Fig. 3: Polarization fraction and intensity maps of HL Tau.
Fig. 4: Stokes I, polarized intensity, and polarization fraction profiles along the major axis of HL Tau (southeast to northwest).

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Data availability

This paper makes use of the following ALMA data: ADS/JAO.ALMA#2016.1.00115.S and ADS/JAO.ALMA#2019.1.01051. The observational data products generated and analysed during the current study are available in the Harvard Dataverse repository (https://dataverse.harvard.edu/dataverse/HLTau_Band7_Pol) under DOIs https://doi.org/10.7910/DVN/MM4V5M and https://doi.org/10.7910/DVN/7CQRBC. Raw ALMA data are available at ALMA Science (https://almascience.nrao.edu/aq/). Additional datasets (for example, modelling) are available from the corresponding author on request.

Code availability

This research made use of APLpy, an open-source plotting package for Python57.

References

  1. Rao, R., Girart, J. M., Lai, S.-P. & Marrone, D. P. Detection of a magnetized disk around a very young protostar. Astrophys. J. Lett. 780, L6 (2014).

    Article  ADS  Google Scholar 

  2. Stephens, I. W. et al. Spatially resolved magnetic field structure in the disk of a T Tauri star. Nature 514, 597–599 (2014).

    Article  ADS  CAS  PubMed  Google Scholar 

  3. Kataoka, A. et al. The evidence of radio polarization induced by the radiative grain alignment and self-scattering of dust grains in a protoplanetary disk. Astrophys. J. Lett. 844, L5 (2017).

    Article  ADS  Google Scholar 

  4. Stephens, I. W. et al. ALMA reveals transition of polarization pattern with wavelength in HL Tau’s disk. Astrophys. J. 851, 55 (2017).

    Article  ADS  Google Scholar 

  5. Harrison, R. E. et al. Dust polarization in four protoplanetary disks at 3 mm: further evidence of multiple origins. Astrophys. J. Lett. 877, L2 (2019).

    Article  ADS  Google Scholar 

  6. Kataoka, A. et al. Millimeter-wave polarization of protoplanetary disks due to dust scattering. Astrophys. J. 809, 78 (2015).

    Article  ADS  Google Scholar 

  7. Yang, H., Li, Z.-Y., Looney, L. & Stephens, I. Inclination-induced polarization of scattered millimetre radiation from protoplanetary discs: the case of HL Tau. Mon. Not. R. Astron. Soc. 456, 2794–2805 (2016).

    Article  ADS  Google Scholar 

  8. Yang, H. Size limit of superparamagnetic inclusions in dust grains and difficulty of magnetic grain alignment in protoplanetary disks. Astrophys. J. 911, 125 (2021).

    Article  ADS  CAS  Google Scholar 

  9. Lin, Z.-Y. D. et al. Thermal emission and scattering by aligned grains: plane-parallel model and application to multiwavelength polarization of the HL Tau disc. Mon. Not. R. Astron. Soc. 512, 3922–3947 (2022).

    Article  ADS  Google Scholar 

  10. Lin, Z.-Y. D. et al. (Sub)millimetre dust polarization of protoplanetary discs from scattering by large millimetre-sized irregular grains. Mon. Not. R. Astron. Soc. 520, 1210–1223 (2023).

    Article  ADS  Google Scholar 

  11. Pohl, A. et al. Investigating dust trapping in transition disks with millimeter-wave polarization. Astron. Astrophys. 593, A12 (2016).

    Article  Google Scholar 

  12. Ohashi, S. & Kataoka, A. Radial variations in grain sizes and dust scale heights in the protoplanetary disk around HD 163296 revealed by ALMA polarization observations. Astrophys. J. 886, 103 (2019).

    Article  ADS  CAS  Google Scholar 

  13. Lin, Z.-Y. D. et al. Validating scattering-induced (sub)millimetre disc polarization through the spectral index, wavelength-dependent polarization pattern, and polarization spectrum: the case of HD 163296. Mon. Not. R. Astron. Soc. 496, 169–181 (2020).

    Article  ADS  Google Scholar 

  14. Galli, P. A. B. et al. The Gould’s Belt Distances Survey (GOBELINS). IV. Distance, depth, and kinematics of the Taurus star-forming region. Astrophys. J. 859, 33 (2018).

    Article  ADS  Google Scholar 

  15. Ohashi, S. et al. Two different grain size distributions within the protoplanetary disk around HD 142527 revealed by ALMA polarization observation. Astrophys. J. 864, 81 (2018).

    Article  ADS  Google Scholar 

  16. ALMA Partnership. et al.The 2014 ALMA Long Baseline Campaign: observations of the strongly lensed submillimeter galaxy HATLAS J090311.6 + 003906 at z = 3.042. Astrophys. J. Lett. 808, L4 (2015).

    Article  ADS  Google Scholar 

  17. Yang, H., Li, Z.-Y., Looney, L. W., Girart, J. M. & Stephens, I. W. Scattering-produced (sub)millimetre polarization in inclined discs: optical depth effects, near-far side asymmetry and dust settling. Mon. Not. R. Astron. Soc. 472, 373–388 (2017).

    Article  ADS  CAS  Google Scholar 

  18. Yang, H., Li, Z.-Y., Stephens, I. W., Kataoka, A. & Looney, L. Does HL Tau disc polarization in ALMA band 3 come from radiatively aligned grains? Mon. Not. R. Astron. Soc. 483, 2371–2381 (2019).

    Article  ADS  CAS  Google Scholar 

  19. Mathis, J. S., Rumpl, W. & Nordsieck, K. H. The size distribution of interstellar grains. Astrophys. J. 217, 425–433 (1977).

    Article  ADS  CAS  Google Scholar 

  20. Planck Collaboration. Planck intermediate results. XIX. An overview of the polarized thermal emission from Galactic dust. Astron. Astrophys. 576, A104 (2015).

  21. Planck Collaboration. Planck intermediate results. XX. Comparison of polarized thermal emission from Galactic dust with simulations of MHD turbulence. Astron. Astrophys. 576, A105 (2015).

  22. Pinte, C. et al. Dust and gas in the disk of HL Tauri: surface density, dust settling, and dust-to-gas ratio. Astrophys. J. 816, 25 (2016).

    Article  ADS  Google Scholar 

  23. Tazaki, R., Tanaka, H., Kataoka, A., Okuzumi, S. & Muto, T. Unveiling dust aggregate structure in protoplanetary disks by millimeter-wave scattering polarization. Astrophys. J. 885, 52 (2019).

    Article  ADS  CAS  Google Scholar 

  24. Yang, H. & Li, Z.-Y. The effects of dust optical properties on the scattering-induced disk polarization by millimeter-sized grains. Astrophys. J. 889, 15 (2020).

    Article  ADS  CAS  Google Scholar 

  25. Andrews, S. M. et al. The Disk Substructures at High Angular Resolution Project (DSHARP). I. Motivation, sample, calibration, and overview. Astrophys. J. Lett. 869, L41 (2018).

    Article  ADS  CAS  Google Scholar 

  26. Hull, C. L. H. et al. TADPOL: a 1.3 mm survey of dust polarization in star-forming cores and regions. Astrophys. J. Suppl. Ser. 213, 13 (2014).

    Article  ADS  Google Scholar 

  27. Hull, C. L. H. & Plambeck, R. L. The 1.3 mm full-Stokes polarization system at CARMA. J. Astron. Instrum. 4, 1550005 (2015).

    Article  Google Scholar 

  28. Birnstiel, T. et al. The Disk Substructures at High Angular Resolution Project (DSHARP). V. Interpreting ALMA maps of protoplanetary disks in terms of a dust model. Astrophys. J. Lett. 869, L45 (2018).

    Article  ADS  CAS  Google Scholar 

  29. Yang, H. et al. Disc polarization from both emission and scattering of magnetically aligned grains: the case of NGC 1333 IRAS 4A1. Mon. Not. R. Astron. Soc. 460, 4109–4121 (2016).

    Article  ADS  Google Scholar 

  30. Whitney, B. A. & Wolff, M. J. Scattering and absorption by aligned grains in circumstellar environments. Astrophys. J. 574, 205–231 (2002).

    Article  ADS  Google Scholar 

  31. Dullemond, C. P. et al. RADMC-3D: a multi-purpose radiative transfer tool (Astrophysics Source Code Library, 2012).

  32. Steinacker, J., Baes, M. & Gordon, K. D. Three-dimensional dust radiative transfer. Ann. Rev. Astron. Astrophys. 51, 63–104 (2013).

    Article  ADS  Google Scholar 

  33. Whitney, B. A. et al. Three-dimensional radiation transfer in young stellar objects. Astrophys. J. Suppl. Ser. 207, 30 (2013).

    Article  ADS  Google Scholar 

  34. Baes, M., Peest, C., Camps, P. & Siebenmorgen, R. Optical depth in polarised Monte Carlo radiative transfer. Astron. Astrophys. 630, A61 (2019).

    Article  ADS  CAS  Google Scholar 

  35. Reissl, S., Wolf, S. & Brauer, R. Radiative transfer with POLARIS. I. Analysis of magnetic fields through synthetic dust continuum polarization measurements. Astron. Astrophys. 593, A87 (2016).

    Article  ADS  Google Scholar 

  36. Peest, C., Camps, P., Stalevski, M., Baes, M. & Siebenmorgen, R. Polarization in Monte Carlo radiative transfer and dust scattering polarization signatures of spiral galaxies. Astron. Astrophys. 601, A92 (2017).

    Article  ADS  Google Scholar 

  37. Bohren, C. F. & Huffman, D. R. Absorption and Scattering of Light by Small Particles (Wiley, 1983).

  38. Mishchenko, M. I., Travis, L. D. & Macke, A. Scattering of light by polydisperse, randomly oriented, finite circular cylinders. Appl. Opt. 35, 4927–4940 (1996).

    Article  ADS  CAS  PubMed  Google Scholar 

  39. Mishchenko, M. I., Travis, L. D. & Mackowski, D. W. T-matrix computations of light scattering by nonspherical particles: a review. J. Quant. Spectrosc. Radiat. Transf. 55, 535–575 (1996).

    Article  ADS  CAS  Google Scholar 

  40. Mori, T. & Kataoka, A. Modeling of the ALMA HL Tau polarization by mixture of grain alignment and self-scattering. Astrophys. J. 908, 153 (2021).

    Article  ADS  Google Scholar 

  41. Hoang, T. & Lazarian, A. Grain alignment induced by radiative torques: effects of internal relaxation of energy and complex radiation field. Astrophys. J. 697, 1316–1333 (2009).

    Article  ADS  Google Scholar 

  42. Chiang, E. I. & Goldreich, P. Spectral energy distributions of T Tauri stars with passive circumstellar disks. Astrophys. J. 490, 368–376 (1997).

    Article  ADS  Google Scholar 

  43. Okuzumi, S., Ueda, T. & Turner, N. J. A global two-layer radiative transfer model for axisymmetric, shadowed protoplanetary disks. Publ. Astron. Soc. Jpn. 74, 828–850 (2022).

    Article  ADS  Google Scholar 

  44. Carrasco-González, C. et al. The radial distribution of dust particles in the HL Tau disk from ALMA and VLA observations. Astrophys. J. 883, 71 (2019).

    Article  ADS  Google Scholar 

  45. Hamaker, J. P. & Bregman, J. D. Understanding radio polarimetry. III. Interpreting the IAU/IEEE definitions of the Stokes parameters. Astron. Astrophys. Suppl. Ser. 117, 161–165 (1996).

    Article  ADS  Google Scholar 

  46. Kataoka, A., Muto, T., Momose, M., Tsukagoshi, T. & Dullemond, C. P. Grain size constraints on HL Tau with polarization signature. Astrophys. J. 820, 54 (2016).

    Article  ADS  Google Scholar 

  47. Hildebrand, R. H. et al. A primer on far-infrared polarimetry. Publ. Astron. Soc. Pac. 112, 1215–1235 (2000).

    Article  ADS  Google Scholar 

  48. Cox, E. G. et al. High-resolution 8 mm and 1 cm polarization of IRAS 4A from the VLA Nascent Disk and Multiplicity (VANDAM) survey. Astrophys. J. Lett. 814, L28 (2015).

    Article  ADS  Google Scholar 

  49. Cox, E. G. et al. ALMA’s polarized view of 10 protostars in the Perseus Molecular Cloud. Astrophys. J. 855, 92 (2018).

    Article  ADS  Google Scholar 

  50. Kwon, W. et al. Highly ordered and pinched magnetic fields in the class 0 protobinary system L1448 IRS 2. Astrophys. J. 879, 25 (2019).

    Article  ADS  CAS  Google Scholar 

  51. Le Gouellec, V. J. M. et al. A statistical analysis of dust polarization properties in ALMA observations of Class 0 protostellar cores. Astron. Astrophys. 644, A11 (2020).

    Article  Google Scholar 

  52. Bacciotti, F. et al. ALMA observations of polarized emission toward the CW Tau and DG Tau protoplanetary disks: constraints on dust grain growth and settling. Astrophys. J. Lett. 865, L12 (2018).

    Article  ADS  Google Scholar 

  53. Mori, T. et al. An observational study for grain dynamics in the AS 209 disk with submillimeter polarization. Astrophys. J. 883, 16 (2019).

    Article  ADS  CAS  Google Scholar 

  54. Sadavoy, S. I. et al. Dust polarization toward embedded protostars in Ophiuchus with ALMA. III. Survey overview. Astrophys. J. Suppl. Ser. 245, 2 (2019).

    Article  ADS  CAS  Google Scholar 

  55. Harrison, R. E. et al. ALMA CN Zeeman observations of AS 209: limits on magnetic field strength and magnetically driven accretion rate. Astrophys. J. 908, 141 (2021).

    Article  ADS  Google Scholar 

  56. Dent, W. R. F. et al. Submillimetre dust polarization and opacity in the HD163296 protoplanetary ring system. Mon. Not. R. Astron. Soc. Lett. 482, L29–L33 (2019).

    Article  ADS  CAS  Google Scholar 

  57. Robitaille, T. & Bressert, E. APLpy: Astronomical Plotting Library in Python (Astrophysics Source Code Library, 2012).

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Acknowledgements

ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan) and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under a cooperative agreement by Associated Universities. Z.-Y.D.L. acknowledges support from NASA 80NSSC18K1095, the Jefferson Scholars Foundation, the NRAO ALMA Student Observing Support (SOS) SOSPA8-003, the Achievements Rewards for College Scientists (ARCS) Foundation Washington Chapter, the Virginia Space Grant Consortium (VSGC) and the UVA research computing (RIVANNA). Z.-Y.L. is supported in part by NASA 80NSSC20K0533 and NSF AST-2307199. L.W.L. and R.H. acknowledge support from NSF AST-1910364 and NSF AST-2307844. C.C.-G. acknowledges support from UNAM DGAPA-PAPIIT (grant no. IG101321) and from CONACyT Ciencia de Frontera (project ID 86372). R.T. acknowledges financial support from the CNES fellowship.

Author information

Authors and Affiliations

  1. Department of Earth, Environment and Physics, Worcester State University, Worcester, MA, USA

    Ian W. Stephens

  2. Department of Astronomy, University of Virginia, Charlottesville, VA, USA

    Zhe-Yu Daniel Lin & Zhi-Yun Li

  3. Instituto Argentino de Radioastronomía, CCT-La Plata (CONICET), Villa Elisa, Argentina

    Manuel Fernández-López

  4. Department of Astronomy, University of Illinois, Urbana, IL, USA

    Leslie W. Looney & Rachel Harrison

  5. Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing, People’s Republic of China

    Haifeng Yang

  6. School of Physics and Astronomy, Monash University, Clayton, Victoria, Australia

    Rachel Harrison

  7. National Astronomical Observatory of Japan, Tokyo, Japan

    Akimasa Kataoka

  8. Instituto de Radioastronomía y Astrofísica (IRyA), Universidad Nacional Autónoma de México (UNAM), Morelia, Mexico

    Carlos Carrasco-Gonzalez

  9. Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo, Japan

    Satoshi Okuzumi

  10. Université Grenoble Alpes, CNRS, Institut de Planétologie et d’Astrophysique (IPAG), Grenoble, France

    Ryo Tazaki

  11. Astronomical Institute, Tohoku University, Sendai, Japan

    Ryo Tazaki

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Contributions

This project was led by I.W.S. Polarization modelling was performed by Z.-Y.D.L. Data reduction was performed by M.F.-L. All authors analysed and discussed the observations and contributed to the paper.

Corresponding author

Correspondence to Ian W. Stephens.

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Extended data figures and tables

Extended Data Fig. 1 Polarization images of the model.

a, The colormap is the Stokes I image in mJy beam−1 and the line segments represent the polarization angle. The length of the segments are proportional to the polarization fraction with a 2% scale bar shown in the bottom. b, The linear polarization fraction image. c, The linear polarized intensity in mJy beam−1. The resolution is shown as a small white or black ellipse in the bottom right of each panel. The concentric ellipses on top of the disk mark the location of the gaps.

Extended Data Fig. 2 Comparisons of the profiles along the major axis between the observation and model.

The first three panels show the Stokes I (panel a), linear polarized intensity (panel b), and the linear polarization fraction (panel c). The observations are plotted in black solid lines with shaded areas showing the standard deviation. The dashed blue lines show the model profiles prior to beam convolution and the orange solid lines show the model profiles after beam convolution. Panel d shows the input optical depth of the model. The horizontal dotted line is where the optical depth is 1. The vertical solid lines mark the locations of the gaps.

Extended Data Fig. 3 Profiles along the minor axis.

These are plotted in a similar way as Extended Data Fig. 2. The additional panel d shows qp (see text for the definition). The positive offset is towards the northeast direction.

Extended Data Fig. 4 Model using effectively oblate grains.

Figure caption is the same as Extended Data Fig. 1, but now with oblate grains. The color scales in panels b and c have been saturated at many locations so that the morphologies of the low-level polarization fractions and intensities are visible.

Extended Data Table 1 The parameters used to produce the disk model and polarization image
Full size table

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Stephens, I.W., Lin, ZY.D., Fernández-López, M. et al. Aligned grains and scattered light found in gaps of planet-forming disk. Nature 623, 705–708 (2023). https://doi.org/10.1038/s41586-023-06648-7

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