2021 Fiscal Year Research-status Report
Using ALMA to understand the origin of dust polarization in the Beta Pic debris disk
| Project/Area Number |
20K14527
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| Research Institution | National Astronomical Observatory of Japan |
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Principal Investigator |
HULL CHARLES 国立天文台, アルマプロジェクト, 特任助教 (70814755)
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | Star formation / Radio astronomy / Polarization / Dust / Debris disks / Magnetic fields / Scattering |
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| Outline of Annual Research Achievements |
The main goal for this grant is to publish the ALMA polarization observations of the Beta Pic debris disk and interpret the results. In FY2020, the data were (almost) fully observed. In spite of the observations not quite being finished, I was still able to download the data from the East Asian ALMA Archive and fully calibrated and imaged them. The data were sufficient for the purposes of our analysis. During FY2021, the image analysis was perfected and the theoretical model to compare with the data was fully developed. The paper was written in the last half of FY2021, and was published in May, 2022 (early FY2022).
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
After overcoming some delays in FY2020, progress in FY2021 was steady. During FY2021, the imaging process was thoroughly analyzed and re-done several times until we were satisfied with the final image products. Since we did not initially detect polarization in the resolved maps, a detailed image analysis was carried out in order to determine that, when we averaged the emission across the entire disk, we could finally achieve a faint detection of polarized dust emission toward Beta Pic. This full-disk-averaged detection then allowed us to constrain the theoretical model built by my theory collaborator (and second author) Haifeng Yang. In the second half of 2021, the parameter space of the theoretical model was thoroughly explored, and we settled upon a model that was a good match for our faint detection of polarization. Once the imaging and modeling were finished, the paper was written toward the end of FY2021, and was published in May, 2022 (early FY2022).
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| Strategy for Future Research Activity |
The main goal of this grant has been achieved. There are a number of future avenues of research that can be pursued. Since we ended up achieving a significant (but very faint) detection of polarization toward Beta Pic, the first obvious future plan would be to consider applying for additional ALMA time to increase the sensitivity of our current observations. The other avenue, which does not require additional observation time, is to perform a deep analysis of the total-intensity image of the dusty component of the Beta Pic debris disk, since the exquisite sensitivity of the ALMA data have allowed us to see some interesting, never-before-seen physical features. Collaborator Mark Wyatt and his group at the University of Cambridge are considering taking on this task in the near future.
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| Causes of Carryover |
As a result of the COVID-19 pandemic, the planned amount of travel expenses were not incurred (although, one significant trip to NAOJ headquarters in Mitaka was accomplished during the summer of 2021). Assuming that restrictions decrease in the next year, the plan for FY2022 will be to perform some in-person meetings using the remaining funding in this grant.
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[Journal Article] Polarization from Aligned Dust Grains in the Beta Pic Debris Disk2022
Author(s)
Hull, Charles L. H. ; Yang, Haifeng ; Cortes, Paulo C. ; Dent, William R. F. ; Kral, Quentin ; Li, Zhi-Yun ; Le Gouellec, Valentin J. M. ; Hughes, A. Meredith ; Milli, Julien ; Teague, Richard ; Wyatt, Mark C.
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Journal Title
The Astrophysical Journal
Volume: 930
Pages: 49
DOI
Peer Reviewed / Open Access / Int'l Joint Research
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[Journal Article] Discovery of Molecular-line Polarization in the Disk of TW Hya2021
Author(s)
Teague, Richard; Hull, Charles L. H.; Guilloteau, Stephane; Bergin, Edwin A.; Dutrey, Anne; Henning, Thomas; Kuiper, Rolf; Semenov, Dmitry; Stephens, Ian W.; Vlemmings, Wouter H. T.
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Journal Title
The Astrophysical Journal
Volume: 922
Pages: 139
DOI
Peer Reviewed / Open Access / Int'l Joint Research
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