Publication Date:
2016-07-25
Description:
The origin of striations aligned along the local magnetic field direction in the translucent envelope of the Taurus molecular cloud is examined with new observations of 12 CO and 13 CO J = 2–1 emission obtained with the 10-m Submillimeter Telescope of the Arizona Radio Observatory. These data identify a periodic pattern of excess blue and redshifted emission that is responsible for the striations. For both 12 CO and 13 CO, spatial variations of the J = 2–1 to J = 1–0 line ratio are small and are not spatially correlated with the striation locations. A medium comprised of unresolved CO emitting substructures (cells) with a beam area filling factor less than unity at any velocity is required to explain the average line ratios and brightness temperatures. We propose that the striations are generated from the modulation of velocities and beam filling factor of the cells as a result of either the Kelvin–Helmholtz instability or magnetosonic waves propagating through the envelope of the Taurus molecular cloud. Both processes are likely common features in molecular clouds that are sub-Alfvénic and may explain low column density, cirrus-like features similarly aligned with the magnetic field observed throughout the interstellar medium in far-infrared surveys of dust emission.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
