Dust-correlated cm-wavelength continuum emission on translucent clouds
  {\zeta} Oph and LDN 1780
  The diffuse cm-wave IR-correlated signal, the "anomalous" CMB foreground, is
thought to arise in the dust in cirrus clouds. We present Cosmic Background
Imager (CBI) cm-wave data of two translucent clouds, {\zeta} Oph and LDN 1780
with the aim of characterising the anomalous emission in the translucent cloud
environment. In {\zeta} Oph, the measured brightness at 31 GHz is 2.4{\sigma}
higher than an extrapolation from 5 GHz measurements assuming a free-free
spectrum on 8 arcmin scales. The SED of this cloud on angular scales of
1{\odot} is dominated by free-free emission in the cm-range. In LDN 1780 we
detected a 3 {\sigma} excess in the SED on angular scales of 1{\odot} that can
be fitted using a spinning dust model. In this cloud, there is a spatial
correlation between the CBI data and IR images, which trace dust. The
correlation is better with near-IR templates (IRAS 12 and 25 {\mu}m) than with
IRAS 100 {\mu}m, which suggests a very small grain origin for the emission at
31 GHz. We calculated the 31 GHz emissivities in both clouds. They are similar
and have intermediate values between that of cirrus clouds and dark clouds.
Nevertheless, we found an indication of an inverse relationship between
emissivity and column density, which further supports the VSGs origin for the
cm-emission since the proportion of big relative to small grains is smaller in
diffuse clouds.
