selected site. It is based on the fact that the [*Spitzer*]{} band at 8.0 $\mu$m contains PAH features at 7.7 and 8.6 $\mu$m.

### [*Herschel*]{} filaments in AFGL 5157 {#ssubsec:u2}

In order to further explore the IRDCs, filaments, and infrared shell, we present the [*Herschel*]{} temperature and column density ($N(\mathrm H_2)$) maps (resolution $\sim$12$''$) in Figures \[fig2\]a and \[fig2\]b, respectively. We retrieved the final processed [*Herschel*]{} temperature and column density ($N(\mathrm H_2)$) maps (resolution $\sim$12$''$) from the publicly available site. These maps were produced as a part of the EU-funded ViaLactea project [@molinari10b]. To produce these [*Herschel*]{} maps, the Bayesian [*PPMAP*]{} procedure [@marsh15] was employed to the [*Herschel*]{} continuum data by @marsh17.

At least three filaments are highlighted in both the [*Herschel*]{} maps (see vertical lines in Figures \[fig2\]a and \[fig2\]b). Among these filaments, an elongated filamentary feature (length $\sim$8.3 pc) is identified using a column density contour with a level of 3.94 $\times$ 10$^{21}$ cm$^{-2}$, which is marked in Figures \[fig2\]a and \[fig2\]b. The total mass of the filamentary feature is estimated to be $\sim$1170 M$_{\odot}$, and is computed using the equation, $M_{area} = \mu_{H_2} m_H Area_{pix} \Sigma N(H_2)$, where $\mu_{H_2}$ is the mean molecular weight per hydrogen molecule 