Dense Molecular Cores Being Externally Heated
  We present results of our study on eight dense cores, previously classified
as starless, using infrared (3-160 {\micron}) imaging observations with
\textit{AKARI} telescope and molecular line (HCN and N$_2$H$^+$) mapping
observations with \textit{KVN} telescope. Combining our results with the
archival IR to mm continuum data, we examined the starless nature of these
eight cores. Two of the eight cores are found to harbor faint protostars having
luminosity of $\sim0.3-4.4$ L$_{\odot}$. The other six cores are found to
remain as starless and probably are in a dynamically transitional state. The
temperature maps produced using multi-wavelength images show an enhancement of
about 3-6 K towards the outer boundary of these cores, suggesting that they are
most likely being heated externally by nearby stars and/or interstellar
radiation fields. Large virial parameters and an over-dominance of red
asymmetric line profiles over the cores may indicate that the cores are set
into either an expansion or an oscillatory motion, probably due to the external
heating. Most of the starless cores show coreshine effect due to the scattering
of light by the micron-size dust grains. This may imply that the age of the
cores is of the order of $\sim10^{5}$ years, being consistent with the
timescale required for the cores to evolve into an oscillatory stage due to the
external perturbation. Our observational results support the idea that the
external feedback from nearby stars and/or interstellar radiation fields may
play an important role in the dynamical evolution of the cores.
