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Ekta Sharma, Archana Soam & Maheswar Gopinathan

Optical polarimetry and molecular line studies of L1157 dark molecular cloud

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Mots-clés : astronomie, astrophysique, molecules, polarimétrie, radio


Filaments are omnipresent in molecular clouds which are believed to fragment into cores. The detailed process of the evolution from filaments to cores depends critically on the physical conditions in the star forming region. This study aims at characterising gas motions using velocity structure and finding the dynamical importance of magnetic fields in the filament morphology. The plane-of-the-sky component of the magnetic field has been measured using optical polarization of the background stars. The orientation is found to be almost perpendicular to the filament implying its dynamical importance in the evolution of the cloud. Optical polarimetric results match very well with the sub millimetre polarization angles obtained in the inner core regions. The magnetic fields are found to have an orientation of 130° east with respect to north. The angular offset between the outflow axis and the magnetic field direction is found to be 25°. Values for parameters like the excitation temperature, optical depth and column densities have been derived using molecular lines. Optically thick lines show non-gaussian features. The non-thermal widths tell about the presence of turbulent motions whereas the C180 lines follow Gaussian features almost at all the locations observed in the filament.

Keywords : astronomy, astrophysics, molecules, polarimetry, radio

To cite this article

Ekta Sharma, Archana Soam & Maheswar Gopinathan, «Optical polarimetry and molecular line studies of L1157 dark molecular cloud», Bulletin de la Société Royale des Sciences de Liège [En ligne], Volume 87 - Année 2018, Actes de colloques, First Belgo-Indian Network for Astronomy & Astrophysics (BINA) workshop - November 2016 - Nainital, India, 266 - 270 URL :

About: Ekta Sharma

Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital 263002, India,

About: Archana Soam

Korea Astronomy & Space Science Institute (KASI), 776 Daedeokdae-ro, Daejeon, Republic of Korea

About: Maheswar Gopinathan

Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital 263002, India