TY - JOUR
T1 - Panchromatic (Sub)millimeter polarization observations of HL Tau unveil aligned scattering grains
AU - Lin, Zhe-Yu Daniel
AU - Li, Zhi-Yun
AU - Stephens, Ian W
AU - Fernández-López, Manuel
AU - Carrasco-González, Carlos
AU - Chandler, Claire J
AU - Pasetto, Alice
AU - Looney, Leslie W
AU - Yang, Haifeng
AU - Harrison, Rachel E
AU - Sadavoy, Sarah I
AU - Henning, Thomas
AU - Hughes, A Meredith
AU - Kataoka, Akimasa
AU - Kwon, Woojin
AU - Muto, Takayuki
AU - Segura-Cox, Dominique
N1 - We thank the referee for a constructive report. Z-YDL 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 UVA research computing (RIVANNA). Z-YL is supported in part by NASA 80NSSC20K0533 and NSF AST-2307199, and AST-1910106. CC-G acknowledges support from UNAM DGAPA-PAPIIT grant IG101321 and from CONACyT Ciencia de Frontera project ID 86372. LWL acknowledges support from NSF 1910364 and NSF 2307844. WK was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (NRF-2021R1F1A1061794). DS-C is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-2102405. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2016.1.00115.S, ADS/JAO.ALMA#2019.1.00134.S, ADS/JAO.ALMA#2019.1.00162.S, ADS/JAO.ALMA#2019.1.01051.S. 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 cooperative agreement by Associated Universities, Inc.
We thank the referee for a constructive report. Z-YDL 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 UVA research computing (RIVANNA). Z-YL is supported in part by NASA 80NSSC20K0533 and NSF AST-2307199, and AST-1910106. CC-G acknowledges support from UNAM DGAPA-PAPIIT grant IG101321 and from CONACyT Ciencia de Frontera project ID 86372. LWL acknowledges support from NSF 1910364 and NSF 2307844. WK was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (NRF-2021R1F1A1061794). DS-C is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-2102405.
PY - 2024/2
Y1 - 2024/2
N2 - Polarization is a unique tool to study the dust grains of protoplanetary discs. Polarization around HL Tau was previously imaged using the Atacama Large Millimeter/submillimeter Array (ALMA) at Bands 3 (3.1 mm), 6 (1.3 mm), and 7 (0.87 mm), showing that the polarization orientation changes across wavelength λ. Polarization at Band 7 is predominantly parallel to the disc minor axis but appears azimuthally oriented at Band 3, with the morphology at Band 6 in between the two. We present new ∼0.2 arcsec (29 au) polarization observations at Q-Band (7.0 mm) using the Karl G. Jansky Very Large Array (VLA) and at Bands 4 (2.1 mm), 5 (1.5 mm), and 7 using ALMA, consolidating HL Tau’s position as the protoplanetary disc with the most complete wavelength coverage in dust polarization. The polarization patterns at Bands 4 and 5 follow the previously identified morphological transition with wavelength. From the azimuthal variation, we decompose the polarization into contributions from scattering (s) and thermal emission (t). s decreases slowly with increasing λ, and t increases more rapidly which are expected from optical depth effects of toroidally aligned scattering prolate grains. The weak λ dependence of s is inconsistent with the simplest case of Rayleigh scattering by small grains in the optically thin limit but can be affected by factors such as optical depth, disc substructure, and dust porosity. The sparse polarization detections from the Q-band image are also consistent with toroidally aligned prolate grains.
AB - Polarization is a unique tool to study the dust grains of protoplanetary discs. Polarization around HL Tau was previously imaged using the Atacama Large Millimeter/submillimeter Array (ALMA) at Bands 3 (3.1 mm), 6 (1.3 mm), and 7 (0.87 mm), showing that the polarization orientation changes across wavelength λ. Polarization at Band 7 is predominantly parallel to the disc minor axis but appears azimuthally oriented at Band 3, with the morphology at Band 6 in between the two. We present new ∼0.2 arcsec (29 au) polarization observations at Q-Band (7.0 mm) using the Karl G. Jansky Very Large Array (VLA) and at Bands 4 (2.1 mm), 5 (1.5 mm), and 7 using ALMA, consolidating HL Tau’s position as the protoplanetary disc with the most complete wavelength coverage in dust polarization. The polarization patterns at Bands 4 and 5 follow the previously identified morphological transition with wavelength. From the azimuthal variation, we decompose the polarization into contributions from scattering (s) and thermal emission (t). s decreases slowly with increasing λ, and t increases more rapidly which are expected from optical depth effects of toroidally aligned scattering prolate grains. The weak λ dependence of s is inconsistent with the simplest case of Rayleigh scattering by small grains in the optically thin limit but can be affected by factors such as optical depth, disc substructure, and dust porosity. The sparse polarization detections from the Q-band image are also consistent with toroidally aligned prolate grains.
KW - polarization
KW - ISM: individual objects: HL Tau
KW - protoplanetary discs
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U2 - 10.1093/mnras/stae040
DO - 10.1093/mnras/stae040
M3 - Article
SN - 0035-8711
VL - 528
SP - 843
EP - 862
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -