R band polarimetry of Cygnus OB2: Implications for the magnetic field geometry and polarization models

Details R band polarimetry of Cygnus OB2: Implications for the magnetic field geometry and polarization models R band polarimetry of Cygnus OB2: Implications for the magnetic field geometry and polarization models

Apr 1994

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994aj....107.1433k&link_type=abstract

The Astronomical Journal, vol. 107, no. 4, p. 1433-1443

Astronomy and Astrophysics

Astronomy

8

Cygnus Constellation, Galactic Radiation, Interstellar Matter, Magnetohydrodynamic Waves, Orion Nebula, Polarization (Waves), Radio Waves, Ubv Spectra, Geomagnetic Latitude, Interstellar Extinction, Interstellar Magnetic Fields, Line Of Sight, Optical Thickness, Solar Longitude

Scientific paper

We present new R band polarimetry of 132 members of the Cygnus OB2 association. From these data we have determined the angular coherence length of the polarization position angle and tested two models for interstellar polarization toward a region where the Galactic magnetic field is expected to be primarily along the line of sight. The polarization magnitudes and position angles in our sample decorrelate on size scales of approximately 0.5 deg, compared to 0.2 deg for the optical extinction. This constrains the variations in the magnetic field orientation to sizes less than 8 pc. The distribution of polarization magnitudes and position angles is consistent with a model which describes the polariztion in terms of preferential extinction in small dark clouds threaded by a two-component magnetic field. One component is constant in direction, while the second is random in orientation and is characterized by the amplitude of Alfven waves in the interstellar medium. A similar model, in which the magnitude of the random component has a Gaussian distribution and an orientation evenly distributed through 4 pi steradians, is also consistent with the data. A previously proposed geometrical model involving two slabs of obscuring material with different magnetic field orientations does not seem adequate given these new data. We explore the predictions of each model for the polarization magnitude and position angle as a function of the orientation of the constant component and point our several key differences that might be exploited to further test their potential for describing interstellar polarization. We find the polarization position angles of stars in the vicinity of Cygnus X-3 are approximately orthogonal to the position angle of the elliptical radio scattering reported by Molnar et al. (1989). If the scattering is taking place on the near side of Cyg OB2, the data are consistent with mechanisms that require the major axis of the scattering ellipse to lie perpendicular to the projected magnetic field.

Affiliated with

Also associated with

No associations

Rating

R band polarimetry of Cygnus OB2: Implications for the magnetic field geometry and polarization models does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with R band polarimetry of Cygnus OB2: Implications for the magnetic field geometry and polarization models, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and R band polarimetry of Cygnus OB2: Implications for the magnetic field geometry and polarization models will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1255157