CO~($J=1-0$) Observations toward Filamentary Molecular Clouds in the
  Galactic Region with $l = [169\arcdeg.75, 174\arcdeg.75], b = [-0\arcdeg.75,
  0\arcdeg.5]$
  We present observations of the CO isotopologues ($^{12}$CO, $^{13}$CO, and
C$^{18}$O) toward the Galactic region with $169\arcdeg.75 \leqslant l \leqslant
174\arcdeg.75$ and $-0\arcdeg.75 \leqslant b \leqslant 0\arcdeg.5$, using the
Purple Mountain Observatory 13.7~m millimeter-wavelength telescope. Based on
the $^{13}$CO~($J = 1-0$) data, we find five molecular clouds within the
velocity range between $-$25 and 8~km~s$^{-1}$ that are all characterized by
conspicuous filamentary structures. We have identified eight filaments with a
length of 6.38--28.45~pc, a mean H$_2$ column density of
0.70$\times$10$^{21}$--6.53$\times$10$^{21}$~cm$^{-2}$, and a line mass of
20.24--161.91~$M_\sun$ pc$^{-1}$, assuming a distance of $\sim$1.7~kpc.
Gaussian fittings to the inner parts of the radial density profiles lead to a
mean FWHM width of 1.13$\pm$0.01~pc. The velocity structures of most filaments
present continuous distributions with slight velocity gradients. We find that
turbulence is the dominant internal pressure to support the fragmentation of
filaments instead of thermal pressure. Most filaments have virial parameters
smaller than 2; thus, they are gravitationally bound. Four filaments have an
LTE line mass close to the virial line mass. We further extract dense clumps
using the $^{13}$CO data and find that 64$\%$ of the clumps are associated with
the filaments. According to the complementary IR data, most filaments have
associated Class~II young stellar objects. Class~I objects are mainly found to
be located in the filaments with a virial parameter close to 1. Within two
virialized filaments, $^{12}$CO outflows have been detected, indicating ongoing
star-forming activity therein.
