تقرير
SPIRou spectropolarimetry of the T Tauri star TW Hydrae: magnetic fields, accretion and planets
| العنوان: | SPIRou spectropolarimetry of the T Tauri star TW Hydrae: magnetic fields, accretion and planets |
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| المؤلفون: | Donati, J. -F., Cristofari, P. I., Lehmann, L. T., Moutou, C., Alencar, S. H. P., Bouvier, J., Arnold, L., Delfosse, X., Artigau, E., Cook, N., Kóspál, Á., Ménard, F., Baruteau, C., Takami, M., Cabrit, S., Hébrard, G., Doyon, R., team, the SPIRou science |
| سنة النشر: | 2024 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Earth and Planetary Astrophysics |
| الوصف: | In this paper we report near-infrared observations of the classical T Tauri star TW Hya with the SPIRou high-resolution spectropolarimeter and velocimeter at the 3.6-m Canada-France-Hawaii Telescope in 2019, 2020, 2021 and 2022. By applying Least-Squares Deconvolution (LSD) to our circularly polarized spectra, we derived longitudinal fields that vary from year to year from -200 to +100 G, and exhibit low-level modulation on the 3.6 d rotation period of TW Hya, despite the star being viewed almost pole-on. We then used Zeeman-Doppler Imaging to invert our sets of unpolarized and circularly-polarized LSD profiles into brightness and magnetic maps of TW Hya in all 4 seasons, and obtain that the large-scale field of this T Tauri star mainly consists of a 1.0-1.2 kG dipole tilted at about 20{\deg} to the rotation axis, whereas the small-scale field reaches strengths of up to 3-4 kG. We find that the large-scale field is strong enough to allow TW Hya to accrete material from the disc on the polar regions at the stellar surface in a more or less geometrically stable accretion pattern, but not to succeed in spinning down the star. We also report the discovery of a radial velocity signal of semi-amplitude $11.1^{+3.3}_{-2.6}$ m/s (detected at 4.3$\sigma$ at a period of 8.3 d in the spectrum of TW Hya, whose origin may be attributed to either a non-axisymmetric density structure in the inner accretion disc, or to a $0.55^{+0.17}_{-0.13}$ Jupiter mass candidate close-in planet (if orbiting in the disc plane), at an orbital distance of $0.075\pm0.001$ au. Comment: MNRAS, in press (23 pages, 16 figures, 6 tables) |
| نوع الوثيقة: | Working Paper |
| الوصول الحر: | http://arxiv.org/abs/2405.04461Test |
| رقم الانضمام: | edsarx.2405.04461 |
| قاعدة البيانات: | arXiv |
| الوصف غير متاح. |