Probing the Turbulent Ambipolar Diffusion Scale in Molecular Clouds with Spectroscopy

Talayeh Hezareh Timea Csengeri Martin Houde 1 Fabrice Herpin 2 S. Bontemps 2
2 FORMATION STELLAIRE 2014
L3AB - Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux, OASU - Observatoire aquitain des sciences de l'univers, LAB - Laboratoire d'Astrophysique de Bordeaux [Pessac], Université Sciences et Technologies - Bordeaux 1
Abstract : We estimate the turbulent ambipolar diffusion length scale and magnetic field strength in the massive dense cores CygX-N03 and CygX-N53, located in the Cygnus-X star-forming region. The method we use requires comparing the velocity dispersions in the spectral line profiles of the coexistent ion and neutral pair H13CN and H13CO+ (J=1-0) at different length scales. We fit Kolmogorov-type power laws to the lower envelopes of the velocity dispersion spectra of the two species. This allows to calculate the turbulent ambipolar diffusion scale, which in turn determines the plane-of-the-sky magnetic field strength. We find turbulent ambipolar diffusion length scales of 3.8+-0.1 mpc and 21.2+-0.4 mpc, and magnetic field strengths of 0.33 mG and 0.76 mG for CygX-N03 and CygX-N53, respectively. These magnetic field values have uncertainties of a factor of a few. Despite a lower signal-to-noise ratio of the data in CygX-N53 than in CygX-N03, and the caveat that its stronger field might stem in part from projection effects, the difference in field strengths suggests different fragmentation activities of the two cores. Even though the quality of our data, obtained with the IRAM Plateau de Bure Interferometer (PdBI), is somewhat inferior to previous single-dish data, we demonstrate that this method is suited also for observations at high spatial resolution.
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Article dans une revue
Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P - Oxford Open Option A, 2014, 438 (1), pp.663-671. 〈10.1093/mnras/stt2237〉
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Contributeur : Marie-Paule Pomies <>
Soumis le : jeudi 5 septembre 2013 - 12:27:07
Dernière modification le : mercredi 29 novembre 2017 - 15:00:23

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Talayeh Hezareh, Timea Csengeri, Martin Houde, Fabrice Herpin, S. Bontemps. Probing the Turbulent Ambipolar Diffusion Scale in Molecular Clouds with Spectroscopy. Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P - Oxford Open Option A, 2014, 438 (1), pp.663-671. 〈10.1093/mnras/stt2237〉. 〈hal-00858387〉

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