Magnetic topologies of young suns: the weak-line T Tauri stars TWA 6 and TWA 8A

被引：18

作者：

Hill, C. A. ^{[1
]}

Folsom, C. P. ^{[1
]}

Donati, J. -F. ^{[1
]}

Herczeg, G. J. ^{[2
]}

Hussain, G. A. J. ^{[1
,3
]}

Alencar, S. H. P. ^{[4
]}

Gregory, S. G. ^{[5
]}

机构：

[1] Univ Toulouse, CNRS, IRAP, UPS,CNES, 14 Ave Edouard Belin, F-31400 Toulouse, France

[2] Peking Univ, Kavli Inst Astron & Astrophys, Yi He Yuan Lu 5, Beijing 100871, Peoples R China

[3] ESO, Karl Schwarzschild Str 2, D-85748 Garching, Germany

[4] Univ Fed Minas Gerais, ICEx, Dept Fis, Av Antonio Carlos 6627, BR-30270901 Belo Horizonte, MG, Brazil

[5] Univ St Andrews, St Andrews KY16 9SS, Fife, Scotland

来源：

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | 2019年 / 484卷 / 04期

基金：

美国国家科学基金会; 欧洲研究理事会;

关键词：

techniques: polarimetric; stars: formation; stars: imaging; stars: individual: TWA 6; stars: individual: TWA 8A; magnetic fields; MAGNETOSPHERIC ACCRETION; SPECTROPOLARIMETRIC OBSERVATIONS; PLANET FORMATION; HOT JUPITER; K-DWARF; ROTATION; FIELDS; EVOLUTION; SEARCH; DYNAMO;

D O I：

10.1093/mnras/stz403

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present a spectropolarimetric study of two weak-line T Tauri stars (wTTSs), TWA 6, and TWA 8A, as part of the MaTYSSE (Magnetic Topologies of Young Stars and the Survival of close-in giant Exoplanets) programme. Both stars display significant Zeeman signatures that we have modelled using Zeeman Doppler Imaging (ZDI). The magnetic field of TWA 6 is split equally between poloidal and toroidal components, with the largest fraction of energy in higher order modes, with a total unsigned flux of 840 G, and a poloidal component tilted 35 degrees from the rotation axis. TWA 8A has a 70 per cent poloidal field, with most of the energy in higher order modes, with an unsigned flux of 1.4 kG (with a magnetic filling factor of 0.2), and a poloidal field tilted 20 degrees from the rotation axis. Spectral fitting of the very strong field in TWA 8A (in individual lines, simultaneously for Stokes I and V) yielded a mean magnetic field strength of 6.0 +/- 0.5 kG. The higher field strengths recovered from spectral fitting suggests that a significant proportion of magnetic energy lies in small-scale fields that are unresolved by ZDI. So far, wTTSs in MaTYSSE appear to show that the poloidal-field axisymmetry correlates with the magnetic field strength. Moreover, it appears that classical T Tauri stars (cTTSs) and wTTSs are mostly poloidal and axisymmetric when mostly convective and cooler than similar to 4300 K, with hotter stars being less axisymmetric and poloidal, regardless of internal structure.

引用

页码：5810 / 5833

页数：24

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