Polarization position angle standard stars: a reassessment of θ and its variability for seventeen stars based on a decade of observations
Article
Article Title | Polarization position angle standard stars: a reassessment of θ and its variability for seventeen stars based on a decade of observations |
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ERA Journal ID | 1074 |
Article Category | Article |
Authors | Cotton, Daniel V., Bailey, Jeremy, Kedziora-Chudczer, Lucyna, Bott, Kimberly, De Horta, Ain Y., Filcek, Normandy, Marshall, Jonathan P., Melville, Graeme, Buzasi, Derek L., Boiko, Ievgeniia, Borsato, Nicholas W., Perkins, Jean, Opitz, Daniela, Melrose, Shannon, Gruning, Gesa, Evensberget, Dag and Zhao, Jinglin |
Journal Title | Monthly Notices of the Royal Astronomical Society |
Journal Citation | 535 (2), pp. 1586-1615 |
Number of Pages | 30 |
Year | 2024 |
Publisher | Oxford University Press |
Place of Publication | United Kingdom |
ISSN | 0035-8711 |
1365-2966 | |
Digital Object Identifier (DOI) | https://doi.org/10.1093/mnras/stae2418 |
Web Address (URL) | https://academic.oup.com/mnras/article/535/2/1586/7840381 |
Abstract | Observations of polarization position angle (θ) standards made from 2014 to 2023 with the High Precision Polarimetric Instrument (HIPPI) and other HIPPI-class polarimeters in both hemispheres are used to investigate their variability. Multiband data were first used to thoroughly recalibrate the instrument performance by bench-marking against carefully selected literature data. A novel co-ordinate difference matrix (CDM) approach – which combines pairs of points – was then used to amalgamate monochromatic (g band) observations from many observing runs and re-determine θ for 17 standard stars. The CDM algorithm was then integrated into a fitting routine and used to establish the impact of stellar variability on the measured position angle scatter. The approach yields variability detections for stars on long time-scales that appear stable over short runs. The best position angle standards are Car, o Sco, HD 154445, HD 161056, and ι 1 Sco, which are stable to ≤0.123◦ . Position angle variability of 0.27–0.82◦ , significant at the 3σ level, is found for 5 standards, including the Luminous Blue Variable HD 160529 and all but one of the other B/A-type supergiants (HD 80558, HD 111613, HD 183143, and 55 Cyg), most of which also appear likely to be variable in polarization magnitude (p) – there is no preferred orientation for the polarization in these objects, which are all classified as α Cygni variables. Despite this we make six key recommendations for observers – relating to data acquisition, processing and reporting – that will allow them to use these standards to achieve < 0.1◦ precision in the telescope position angle with similar instrumentation, and allow data sets to be combined more accurately. |
Keywords | instrumentation: polarimeters; techniques: polarimetric; supergiants |
Contains Sensitive Content | Does not contain sensitive content |
ANZSRC Field of Research 2020 | 5101. Astronomical sciences |
Byline Affiliations | Monterey Institute for Research in Astronomy, United States |
Western Sydney University | |
University of New South Wales | |
Centre for Astrophysics | |
University of California Riverside, United Sates | |
University of Washington, United States | |
University of Central Florida, United States | |
York School, United States | |
Willamette University, United States | |
Academia Sinica Institute of Astronomy and Astrophysics, Taiwan | |
University of Wollongong | |
Florida Gulf Coast University, United States | |
Monterey Peninsula College, United States | |
Lund University, Sweden | |
Macquarie University | |
University for Development, Chile | |
University of Oldenburg, Germany | |
Leiden University, Netherlands | |
Pennsylvania State University, United States |
https://research.usq.edu.au/item/zqzxx/polarization-position-angle-standard-stars-a-reassessment-of-and-its-variability-for-seventeen-stars-based-on-a-decade-of-observations
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