  We report on results of near-infrared and optical observations of the mm disk
embedded in the Bok globule CB 26 (Launhardt & Sargent 2001). The near-infrared
images show a bipolar reflection nebula with a central extinction lane which
coincides with the mm disk. Imaging polarimetry of this object yielded a
polarization pattern which is typical for a young stellar object surrounded by
a large circumstellar disk and an envelope, seen almost edge-on. The strong
linear polarization in the bipolar lobes is caused by single scattering at dust
grains and allowed to locate the illuminating source which coincides with the
center of the mm disk. The spectral energy distribution of the YSO embedded in
CB 26 resembles that of a ClassI source with a luminosity of 0.5 L_sun.Using
the pre-main-sequence evolutionary tracks and the stellar mass inferred from
the rotation curve of the disk, we derive an age of the system of <10^6 yr.
H_alpha and [SII] narrow-band imaging as well as optical spectroscopy revealed
an Herbig-Haro object 6.15 arcmin northwest of CB 26 YSO 1, perfectly aligned
with the symmetry axis of the bipolar nebula. This Herbig-Haro object (HH 494)
indicates ongoing accretion and outflow activity in CB 26 YSO 1. Its excitation
characteristics indicate that the Herbig-Haro flow is propagating into a
low-density environment. We suggest that CB 26 YSO 1 represents the transition
stage between embedded protostellar accretion disks and more evolved
protoplanetary disks around T Tauri stars in an undisturbed environment.
