Magnetic field measurements in a sample of Class I and flat-spectrum protostars observed with SPIRou

Rapport Preprint Magnetic field measurements in a sample of Class I and flat-spectrum protostars observed with SPIRou eng 2026 author Drouglazet L. author Alecian E. author Sousa A. author Cristofari P. I. author Artigau E. author Bouvier J. author Carmona A. author Cook N. J. author Dougados C. author Duchêne G. author Folsom C. P. author Nowacki H. author Perraut K. author Alencar S. H. P. author Amard Louis 775303 Département d'astronomie (ASTRO) author Audard Marc 0000-0003-4721-034X 646393 Département d'astronomie (ASTRO) author Cabrit S. author Donati J. -F. author Grankin K. author Grosso N. author Kochukhov O. author Kóspál Á. author Gouellec V. J. M. Le author Manchon L. author Pantolmos G. author Petit P. author Petitdemange L. author Devaraj R. author Shang H. author Takami M. 10.48550/arxiv.2603.17482 Magnetic fields play a crucial role throughout stellar evolution, regulating angular momentum, channelling accretion, and launching jets and outflows. While the magnetic properties of Classical T Tauri Stars (CTTS) are well characterised, those of their progenitors, Class I and Flat-Spectrum (FS) protostars, remain poorly constrained due to observational challenges linked to their embedded nature. We aim to detect and characterise large-scale magnetic fields in a sample of Class I and FS protostars, which are expected to host strong dynamo-generated fields. Using SPIRou, a high-resolution near-infrared spectropolarimeter, we analysed polarised spectra and applied the Least Squares Deconvolution (LSD) technique to extract magnetic signatures and measure longitudinal fields from Stokes V profiles. We report new detections of large-scale magnetic fields in 5 FS protostars. Including the previously known magnetic FS protostar V347 Aur, 40% of our sample (15 objects) is confirmed to be magnetic. These stars exhibit clear Zeeman signatures, with longitudinal field strengths ranging from ~80 to ~200 G. The remaining targets show no detectable Stokes V signature, with upper limits on dipolar fields between 500 G and >5 kG. These results indicate that Class I and FS protostars can host large-scale magnetic fields, possibly weaker than in CTTS, supporting the idea that magnetic processes are already active during the main accretion phase and may influence star-disk interactions from the earliest stages. Solar and Stellar Astrophysics (astro-ph.SR) FOS: Physical sciences Dewey 520 26 Département d'astronomie 12 false 35600bb5-66e9-43c8-b655-0f7a2cdceb5b Preprint Public Preprint_from_arxiv.pdf 4309264 application/pdf 8138390a439ce8a8e8abcdf20960c24c5b3d37ba29a8f52ead6945996e5881e0 openAccess Faculté des sciences / Département d'astronomie

Title	Year	Views	Downloads

Magnetic field measurements in a sample of Class I and flat-spectrum protostars observed with SPIRou	2026	1	25
Évolution de la rotation des étoiles jeunes de faible masse	2017	315	1

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Amard, Louis