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
Journal article, 2020

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.

Author

Ko Yun Huang

University of Illinois

A. Kemball

University of Illinois

Wouter Vlemmings

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Galactic Astrophysics

Shih-Ping Lai

National Tsing Hua University

Louis Yang

University of Tokyo

I. Agudo

Institute of Astrophysics of Andalusia (IAA)

Astrophysical Journal

0004-637X (ISSN) 1538-4357 (eISSN)

Vol. 899 2 152

Subject Categories

Astronomy, Astrophysics and Cosmology

Other Physics Topics

Condensed Matter Physics

DOI

10.3847/1538-4357/aba122

More information

Latest update

4/1/2021 1