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An early transition to magnetic supercriticality in star formation

Magnetic fields have an important role in the evolution of interstellar medium and star formation(1,2). As the only direct probe of interstellar field strength, credible Zeeman measurements remain sparse owing to the lack of suitable Zeeman probes, particularly for cold, molecular gas(3). Here we re...

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Autores principales: Ching, T.-C., Li, D., Heiles, C., Li, Z.-Y., Qian, L., Yue, Y. L., Tang, J., Jiao, S. H.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8732270/
https://www.ncbi.nlm.nih.gov/pubmed/34987214
http://dx.doi.org/10.1038/s41586-021-04159-x
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author Ching, T.-C.
Li, D.
Heiles, C.
Li, Z.-Y.
Qian, L.
Yue, Y. L.
Tang, J.
Jiao, S. H.
author_facet Ching, T.-C.
Li, D.
Heiles, C.
Li, Z.-Y.
Qian, L.
Yue, Y. L.
Tang, J.
Jiao, S. H.
author_sort Ching, T.-C.
collection PubMed
description Magnetic fields have an important role in the evolution of interstellar medium and star formation(1,2). As the only direct probe of interstellar field strength, credible Zeeman measurements remain sparse owing to the lack of suitable Zeeman probes, particularly for cold, molecular gas(3). Here we report the detection of a magnetic field of +3.8 ± 0.3 microgauss through the H I narrow self-absorption (HINSA)(4,5) towards L1544(6,7)—a well-studied prototypical prestellar core in an early transition between starless and protostellar phases(8–10) characterized by a high central number density(11) and a low central temperature(12). A combined analysis of the Zeeman measurements of quasar H I absorption, H I emission, OH emission and HINSA reveals a coherent magnetic field from the atomic cold neutral medium (CNM) to the molecular envelope. The molecular envelope traced by the HINSA is found to be magnetically supercritical, with a field strength comparable to that of the surrounding diffuse, magnetically subcritical CNM despite a large increase in density. The reduction of the magnetic flux relative to the mass, which is necessary for star formation, thus seems to have already happened during the transition from the diffuse CNM to the molecular gas traced by the HINSA. This is earlier than envisioned in the classical picture where magnetically supercritical cores capable of collapsing into stars form out of magnetically subcritical envelopes(13,14).
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spelling pubmed-87322702022-01-18 An early transition to magnetic supercriticality in star formation Ching, T.-C. Li, D. Heiles, C. Li, Z.-Y. Qian, L. Yue, Y. L. Tang, J. Jiao, S. H. Nature Article Magnetic fields have an important role in the evolution of interstellar medium and star formation(1,2). As the only direct probe of interstellar field strength, credible Zeeman measurements remain sparse owing to the lack of suitable Zeeman probes, particularly for cold, molecular gas(3). Here we report the detection of a magnetic field of +3.8 ± 0.3 microgauss through the H I narrow self-absorption (HINSA)(4,5) towards L1544(6,7)—a well-studied prototypical prestellar core in an early transition between starless and protostellar phases(8–10) characterized by a high central number density(11) and a low central temperature(12). A combined analysis of the Zeeman measurements of quasar H I absorption, H I emission, OH emission and HINSA reveals a coherent magnetic field from the atomic cold neutral medium (CNM) to the molecular envelope. The molecular envelope traced by the HINSA is found to be magnetically supercritical, with a field strength comparable to that of the surrounding diffuse, magnetically subcritical CNM despite a large increase in density. The reduction of the magnetic flux relative to the mass, which is necessary for star formation, thus seems to have already happened during the transition from the diffuse CNM to the molecular gas traced by the HINSA. This is earlier than envisioned in the classical picture where magnetically supercritical cores capable of collapsing into stars form out of magnetically subcritical envelopes(13,14). Nature Publishing Group UK 2022-01-05 2022 /pmc/articles/PMC8732270/ /pubmed/34987214 http://dx.doi.org/10.1038/s41586-021-04159-x Text en © The Author(s) 2022 https://creativecommons.org/licenses/by/4.0/Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Article
Ching, T.-C.
Li, D.
Heiles, C.
Li, Z.-Y.
Qian, L.
Yue, Y. L.
Tang, J.
Jiao, S. H.
An early transition to magnetic supercriticality in star formation
title An early transition to magnetic supercriticality in star formation
title_full An early transition to magnetic supercriticality in star formation
title_fullStr An early transition to magnetic supercriticality in star formation
title_full_unstemmed An early transition to magnetic supercriticality in star formation
title_short An early transition to magnetic supercriticality in star formation
title_sort early transition to magnetic supercriticality in star formation
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8732270/
https://www.ncbi.nlm.nih.gov/pubmed/34987214
http://dx.doi.org/10.1038/s41586-021-04159-x
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