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

We present optical and near-infrared stellar polarization observations towardthe dark filamentary clouds associated with IC5146. The data allow us toinvestigate the dust properties (this paper) and the magnetic field structure(Paper II). A total of 2022 background stars were detected in $R_{c}$-, $i'$-,$H$-, and/or $K$-bands to $A_V \lesssim 25$ mag. The ratio of the polarizationpercentage at different wavelengths provides an estimate of $\lambda_{max}$,the wavelength of peak polarization, which is an indicator of the small-sizecutoff of the grain size distribution. The grain size distribution seems tosignificantly change at $A_V \sim$ 3 mag, where both the average and dispersionof $P_{R_c}/P_{H}$ decrease. In addition, we found $\lambda_{max}$ $\sim$0.6-0.9 $\mu$m for $A_V>2.5$ mag, which is larger than the $\sim$ 0.55 $\mu$min the general ISM, suggesting that grain growth has already started in low$A_V$ regions. Our data also reveal that polarization efficiency (PE $\equivP_{\lambda}/A_V$) decreases with $A_V$ as a power-law in $R_c$-, $i'$-, and$K$-bands with indices of -0.71$\pm$0.10, -1.23$\pm$0.10 and -0.53$\pm$0.09.However, $H$-band data show a power index change; the PE varies with $A_V$steeply (index of -0.95$\pm$0.30) when $A_V < 2.88\pm0.67$ mag but softly(index of -0.25$\pm$0.06) for greater $A_V$ values. The soft decay of PE inhigh $A_V$ regions is consistent with the Radiative Aligned Torque model,suggesting that our data trace the magnetic field to $A_V \sim 20$ mag.Furthermore, the breakpoint found in $H$-band is similar to the $A_V$ where wefound the $P_{R_c}/P_{H}$ dispersion significantly decreased. Therefore, theflat PE-$A_V$ in high $A_V$ regions implies that the power index changes resultfrom additional grain growth.

Multi-wavelength Stellar Polarimetry of the Filamentary Cloud IC5146: I. Dust Properties