Nicholson, B.A. and Hussain, G. and Donati, J.-F. and Wright, D. and Folsom, C.P. and Wittenmyer, R. and Okumura, J. and Carter, B.D. 
ORCID: https://orcid.org/0000-0003-0035-8769
(2021)
The surface magnetic activity of the weak-line T Tauri stars TWA 7 and TWA 25.
Monthly Notices of the Royal Astronomical Society, 504 (2).
pp. 2461-2473.
ISSN 0035-8711
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Text (Published Version)
The Surface Magnetic Activity of the Weak-Line T Tauri Stars TWA.pdf Available under License Creative Commons Attribution 4.0. Download (5MB) | Preview |
Abstract
We present an analysis of spectropolarimetric observations of the low-mass weak-line T Tauri stars TWA 25 and TWA 7. The large-scale surface magnetic fields have been reconstructed for both stars using the technique of Zeeman Doppler imaging. Our surface maps reveal predominantly toroidal and non-axisymmetric fields for both stars. These maps reinforce the wide range of surface magnetic fields that have been recovered, particularly in pre-main sequence stars that have stopped accreting from the (now depleted) central regions of their discs. We reconstruct the large scale surface brightness distributions for both stars, and use these reconstructions to filter out the activity-induced radial velocity jitter, reducing the RMS of the radial velocity variations from 495 to 32 ms(-1) for TWA 25, and from 127 to 36 ms(-1) for TWA 7, ruling out the presence of close-in giant planets for both stars. The TWA 7 radial velocities provide an example of a case where the activity-induced radial velocity variations mimic a Keplerian signal that is uncorrelated with the spectral activity indices. This shows the usefulness of longitudinal magnetic field measurements in identifying activity-induced radial velocity variations.
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| Item Type: | Article (Commonwealth Reporting Category C) |
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| Refereed: | Yes |
| Item Status: | Live Archive |
| Additional Information: | 2021 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. |
| Faculty/School / Institute/Centre: | Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -) |
| Faculty/School / Institute/Centre: | Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -) |
| Date Deposited: | 10 Jan 2022 03:05 |
| Last Modified: | 10 Jan 2022 03:44 |
| Uncontrolled Keywords: | magnetic fields; techniques: polarimetric; stars: formation; stars:; imaging; stars: individual: TWA 7; stars: individual: TWA 25; Astrophysics - Solar and Stellar Astrophysics; Astrophysics - Earth and; Planetary Astrophysics |
| Fields of Research (2008): | 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems |
| Fields of Research (2020): | 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems |
| Socio-Economic Objectives (2008): | E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences |
| Socio-Economic Objectives (2020): | 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences |
| Identification Number or DOI: | https://doi.org/10.1093/mnras/stab879 |
| URI: | http://eprints.usq.edu.au/id/eprint/45063 |
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