CN Zeeman measurements in star formation regions

Edith Falgarone (1) , Thomas H. Troland (2) , Richard M. Crutcher (3) , Gabriel Paubert (4)

1 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
2 Department of Physics and Astronomy, University of Kentucky
3 Department of Astronomy, University of Illinois
4 IRAM - Instituto de Radio Astronomía Milimétrica

Aims: Magnetic fields play a primordial role in the star formation process. The Zeeman effect on the CN radical lines is one of the few methods of measuring magnetic fields in the dense gas of star formation regions.
Methods: We report new observations of the Zeeman effect on seven hyperfine CN N = 1-0 lines in the direction of 14 regions of star formation.
Results: We have improved the sensitivity of previous detections, and obtained five new detections. Good upper limits are also achieved. The probability distribution of the line-of-sight field intensity, including non-detections, provides a median value of the total field B_tot = 0.56 mG while the average density of the medium sampled is n(H_2) = 4.5 × 10^5cm^-3. We show that the CN line probably samples regions similar to those traced by CS and that the magnetic field observed mostly pervades the dense cores. The dense cores are found to be critical to slightly supercritical with a mean mass-to-flux ratio M/Phi ˜ 1 to 4 with respect to critical. Their turbulent and magnetic energies are in approximate equipartition.

Domaines: Astrophysique [astro-ph]; Planète et Univers [physics]

Edith Falgarone, Thomas H. Troland, Richard M. Crutcher, Gabriel Paubert. CN Zeeman measurements in star formation regions. Astronomy and Astrophysics - A&A, 2008, 487, pp.247-252. ⟨10.1051/0004-6361:200809577⟩. ⟨hal-03785471⟩