English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Interstellar grain alignment studies are currently experiencing a renaissancedue to the development of a new quantitative theory based on RadiativeAlignment Torques (RAT). One of the distinguishing predictions of this theoryis a dependence of the grain alignment efficiency on the relative angle($\Psi$) between the magnetic field and the anisotropy direction of theradiation field. In an earlier study we found observational evidence for suchan effect from observations of the polarization around the star HD 97300 in theChamaeleon I cloud. However, due to the large uncertainties in the measuredvisual extinctions, the result was uncertain.  By acquiring explicit spectral classification of the polarization targets, wehave sought to perform a more precise reanalysis of the existing polarimetrydata.  We have obtained new spectral types for the stars in our for our polarizationsample, which we combine with photometric data from the literature to deriveaccurate visual extinctions for our sample of background field stars. Thisallows a high accuracy test of the grain alignment efficiency as a function of$\Psi$.  We confirm and improve the measured accuracy of the variability of the grainalignment efficiency with $\Psi$, seen in the earlier study. We note that thegrain temperature (heating) also shows a dependence on $\Psi$ which weinterpret as a natural effect of the projection of the grain surface to theilluminating radiation source. This dependence also allows us to derive anestimate of the fraction of aligned grains in the cloud.

astronomy and astrophysics

Angle-dependent radiative grain alignment; Confirmation of a magnetic  field - radiation anisotropy angle dependence on the efficiency of  interstellar grain alignment