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

Fuente: arXiv

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Bibliographic Details
Main Authors:	Drouglazet, L., Alecian, E., Sousa, A., Cristofari, P. I., Artigau, E., Bouvier, J., Carmona, A., Cook, N. J., Dougados, C., Duchêne, G., Folsom, C. P., Nowacki, H., Perraut, K., Alencar, S. H. P., Amard, L., Audard, M., Cabrit, S., Donati, J. -F., Grankin, K., Grosso, N., Kochukhov, O., Kóspál, Á., Gouellec, V. J. M. Le, Manchon, L., Pantolmos, G., Petit, P., Petitdemange, L., Devaraj, R., Shang, H., Takami, M.
Format:	Preprint
Published:	2026
Subjects:	Solar and Stellar Astrophysics
Online Access:	Acceder al recurso
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_version_	1866910173804625920
author	Drouglazet, L. Alecian, E. Sousa, A. Cristofari, P. I. Artigau, E. Bouvier, J. Carmona, A. Cook, N. J. Dougados, C. Duchêne, G. Folsom, C. P. Nowacki, H. Perraut, K. Alencar, S. H. P. Amard, L. Audard, M. Cabrit, S. Donati, J. -F. Grankin, K. Grosso, N. Kochukhov, O. Kóspál, Á. Gouellec, V. J. M. Le Manchon, L. Pantolmos, G. Petit, P. Petitdemange, L. Devaraj, R. Shang, H. Takami, M.
author_facet	Drouglazet, L. Alecian, E. Sousa, A. Cristofari, P. I. Artigau, E. Bouvier, J. Carmona, A. Cook, N. J. Dougados, C. Duchêne, G. Folsom, C. P. Nowacki, H. Perraut, K. Alencar, S. H. P. Amard, L. Audard, M. Cabrit, S. Donati, J. -F. Grankin, K. Grosso, N. Kochukhov, O. Kóspál, Á. Gouellec, V. J. M. Le Manchon, L. Pantolmos, G. Petit, P. Petitdemange, L. Devaraj, R. Shang, H. Takami, M.
contents	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.
format	Preprint
id	arxiv_https___arxiv_org_abs_2603_17482
institution	arXiv
publishDate	2026
record_format	arxiv
spellingShingle	Magnetic field measurements in a sample of Class I and flat-spectrum protostars observed with SPIRou Drouglazet, L. Alecian, E. Sousa, A. Cristofari, P. I. Artigau, E. Bouvier, J. Carmona, A. Cook, N. J. Dougados, C. Duchêne, G. Folsom, C. P. Nowacki, H. Perraut, K. Alencar, S. H. P. Amard, L. Audard, M. Cabrit, S. Donati, J. -F. Grankin, K. Grosso, N. Kochukhov, O. Kóspál, Á. Gouellec, V. J. M. Le Manchon, L. Pantolmos, G. Petit, P. Petitdemange, L. Devaraj, R. Shang, H. Takami, M. Solar and Stellar Astrophysics 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.
title	Magnetic field measurements in a sample of Class I and flat-spectrum protostars observed with SPIRou
topic	Solar and Stellar Astrophysics
url	https://arxiv.org/abs/2603.17482