  Circularly polarized 3.5 cm continuum emission was detected toward three
radio sources in the R CrA region using the Very Large Array. The Class I
protostar IRS 5b persistently showed polarized radio emission with a constant
helicity over 8 yr, which suggests that its magnetosphere has a stable
configuration. There is a good correlation between the Stokes I and Stokes V
fluxes, and the fractional polarization is about 0.17. During active phases the
fractional polarization is a weakly decreasing function of Stokes I flux, which
suggests that IRS 5b is phenomenologically similar to other types of flare
stars such as RS CVn binaries. The variability timescale of the polarized flux
is about a month, and the magnetosphere of IRS 5b must be very large in size.
The Class I protostar IRS 7A was detected once in circularly polarized radio
emission, even though IRS 7A drives a thermal radio jet. This detection implies
that the radio emission from the magnetosphere of a young protostar can escape
the absorption by the partially ionized wind at least once in a while. The
properties of IRS 7A and IRS 5b suggests that Class I protostars have organized
peristellar magnetic fields of a few kilogauss and that the detectability of
magnetospheric emission may depend on the evolutionary status of protostar.
Also reported is the detection of circularly polarized radio emission toward
the variable radio source B5.
