Mapping Circumstellar Magnetic Fields of Late-type Evolved Stars with the Goldreich-Kylafis Effect: CARMA Observations at λ1.3 mm of R Crt and R Leo

DOI: 
10.3847/1538-4357/aba122
Publication date: 
22/09/2020
Main author: 
Huang K.-Y.
IAA authors: 
Agudo, I.
Authors: 
Huang K.-Y., Kemball A.J., Vlemmings W.H.T., Lai S.-P., Yang L., Agudo I.
Journal: 
Astrophysical Journal
Refereed: 
Yes
Publication type: 
Article
Volume: 
899.0
Pages: 
152
Number: 
152
Abstract: 
Mapping magnetic fields is the key to resolving the unclear physical picture of circumstellar magnetic fields in late-type evolved stars. Observations of linearly polarized emission from thermal molecular line transitions due to the Goldreich-Kylafis (G-K) effect provide valuable insights into the magnetic field geometry in these sources that are complementary to other key studies. In this paper, we present the detection of spectral-line polarization from both the thermal J = 2-1 CO line and the v = 1, J = 5-4 SiO maser line toward two thermal-pulsating asymptotic giant branch stars, R Crt and R Leo. The observed fractional linear polarization in the CO emission is measured as m l ∼ 3.1% and m l ∼ 9.7% for R Crt and R Leo, respectively. A circumstellar envelope (CSE) model profile and the associated parameters are estimated and used as input to a more detailed modeling of the predicted linear polarization expected from the G-K effect. The observed thermal line polarization level is consistent with the predicted results from the G-K model for R Crt; additional effects need to be considered for R Leo. © 2020. The American Astronomical Society. All rights reserved.
Database: 
SCOPUS
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2020ApJ...899..152H/abstract
ADS Bibcode: 
2020ApJ...899..152H