SPIRou observations of the young planet-hosting star PDS 70

ABSTRACT This paper presents near-infrared spectropolarimetric and velocimetric observations of the young planet-hosting T Tauri star PDS 70, collected with SPIRou at the 3.6-m Canada–France–Hawaii Telescope from 2020 to 2024. Clear Zeeman signatures from magnetic fields at the surface of PDS 70 are detected in our data set of 40 circularly polarized spectra. Longitudinal fields inferred from Zeeman signatures, ranging from $-116$ to 176 G, are modulated on a time-scale of $3.008\pm 0.006$ d, confirming that this is the rotation period of PDS 70. Applying Zeeman–Doppler imaging to subsets of unpolarized and circularly polarized line profiles, we show that PDS 70 hosts low-contrast brightness spots and a large-scale magnetic field in its photosphere, featuring in particular a dipole component of strength 200–420 G that evolves on a time-scale of months. From the broadening of spectral lines, we also infer that PDS 70 hosts a small-scale field of $2.51\pm 0.12$ kG. Radial velocities derived from unpolarized line profiles are rotationally modulated as well, and exhibit additional longer term chromatic variability, most likely attributable to magnetic activity rather than to a close-in giant planet (with a 3$\sigma$ upper limit on its minimum mass of $\simeq$4 at a distance of $\simeq$0.2 au). We finally confirm that accretion occurs at the surface of PDS 70, generating modulated redshifted absorption in the 1083.3-nm He i triplet, and show that the large-scale magnetic field, often strong enough to disrupt the inner accretion disc up to the corotation radius, weakens as the star gets fainter and redder (as in 2022), suggesting that dust from the disc more easily penetrates the stellar magnetosphere in such phases.

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Journal
Monthly Notices of the Royal Astronomical Society
Published
2024-11-08
DOI
https://doi.org/10.1093/mnras/stae2506
Citations
2
Primary Topic
Astronomy and Astrophysical Research
Type
article
Field-Weighted Citation Impact
1.01

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article

SPIRou observations of the young planet-hosting star PDS 70

René Doyon, J.-D. do Nascimento, A Carmona, C. Moutou et al.
2 citations
Monthly Notices of the Royal Astronomical Society
Astronomy and Astrophysical Research
1.01
article

SPIRou observations of the young planet-hosting star PDS 70

René Doyon, J.-D. do Nascimento, A Carmona, C. Moutou, Á. Kóspál, F. Ménard, J.‐F. Donati, Étienne Artigau, S. H. P. Alencar, M. Takami, Hsien Shang, P. I. Cristofari, Eric Gaidos, J. Gregorio‐Hetem, J. Bouvier
article en
2 citations

Abstract

ABSTRACT This paper presents near-infrared spectropolarimetric and velocimetric observations of the young planet-hosting T Tauri star PDS 70, collected with SPIRou at the 3.6-m Canada–France–Hawaii Telescope from 2020 to 2024. Clear Zeeman signatures from magnetic fields at the surface of PDS 70 are detected in our data set of 40 circularly polarized spectra. Longitudinal fields inferred from Zeeman signatures, ranging from $-116$ to 176 G, are modulated on a time-scale of $3.008\pm 0.006$ d, confirming that this is the rotation period of PDS 70. Applying Zeeman–Doppler imaging to subsets of unpolarized and circularly polarized line profiles, we show that PDS 70 hosts low-contrast brightness spots and a large-scale magnetic field in its photosphere, featuring in particular a dipole component of strength 200–420 G that evolves on a time-scale of months. From the broadening of spectral lines, we also infer that PDS 70 hosts a small-scale field of $2.51\pm 0.12$ kG. Radial velocities derived from unpolarized line profiles are rotationally modulated as well, and exhibit additional longer term chromatic variability, most likely attributable to magnetic activity rather than to a close-in giant planet (with a 3$\sigma$ upper limit on its minimum mass of $\simeq$4 at a distance of $\simeq$0.2 au). We finally confirm that accretion occurs at the surface of PDS 70, generating modulated redshifted absorption in the 1083.3-nm He i triplet, and show that the large-scale magnetic field, often strong enough to disrupt the inner accretion disc up to the corotation radius, weakens as the star gets fainter and redder (as in 2022), suggesting that dust from the disc more easily penetrates the stellar magnetosphere in such phases.

Monthly Notices of the Royal Astronomical SocietyVol. 535(4)
Eötvös Loránd University (HU), Universidade Federal de Minas Gerais (BR), University of Hawaiʻi at Mānoa (US), Centre National de la Recherche Scientifique (FR), Institute of Astronomy and Astrophysics, Academia Sinica (TW), European Southern Observatory (DE), Université Fédérale de Toulouse Midi-Pyrénées (FR), Universidade de São Paulo (BR), Konkoly Observatory (HU), Universidade Federal do Rio Grande do Norte (BR), Unidade Integrada de Farmacologia e Gastroenterologia (BR), FZU ‒ Institute of Physics of the Academy of Sciences of the Czech Republic (CZ), Center for Astrophysics Harvard & Smithsonian (US), HUN-REN Research Centre for Astronomy and Earth Sciences (HU), Université de Montréal (CA), Université Grenoble Alpes (FR)
Agence Nationale de la Recherche, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Centre National de la Recherche Scientifique, Fundação de Amparo à Pesquisa do Estado de Minas Gerais, Nemzeti Kutatási Fejlesztési és Innovációs Hivatal, Horizon 2020 Framework Programme, HORIZON EUROPE Framework Programme, National Research Council Canada
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Astronomy and Astrophysical Research
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