Little is known about the nature of dust and magnetic fields in stellar bowshock nebulae, or how their massive runaway host stars shape these properties. Zeta Opiuchi is an ideal target to test the structure of bowshock dust grains, as its bowshock is nearby and isolated from confusing background sources. We obtained V-band polarimetry of 27 stars behind the bowshock with the Optipol polarimeter installed on the 2.3-m Wyoming Infrared Observatory Telescope. We also acquired optical spectroscopy from the Dual Imaging Spectrograph at Apache Point Observatory for 21 of these targets. We use these data to determine magnetic field orientation along each sight line with polarization vectors as well as dust composition with extinction estimates. Zeta Oph is thought to have two major clouds in the foreground (Wolstencroft et al. 1984), leading us to subtract the polarization of Zeta Oph itself from our background targets to probe behind these clouds and through the nebula itself. This leaves us with polarization vectors that are parallel to Zeta Oph's direction of motion. This result is contrary to the claims of Meyer et al. (2016) that Zeta Oph is moving through ISM where the magnetic field is not aligned with the direction of motion, but consistent with the polarization measurements of the bowshock from galactic source IRS 8 by Rauch et al. (2013). We expect the polarization data to allow us to distinguish between radiative and magnetic alignment mechanisms.
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020