  The unidentified very-high-energy (VHE; E $>$ 0.1 TeV) $\gamma$-ray source,
HESS J1826$-$130, was discovered with the High Energy Stereoscopic System
(HESS) in the Galactic plane. The analysis of 215 h of HESS data has revealed a
steady $\gamma$-ray flux from HESS J1826$-$130, which appears extended with a
half-width of 0.21$^{\circ}$ $\pm$ 0.02$^{\circ}_{\text{stat}}$ $\pm$
0.05$^{\circ}_{\text{sys}}$. The source spectrum is best fit with either a
power-law function with a spectral index $\Gamma$ = 1.78 $\pm$
0.10$_{\text{stat}}$ $\pm$ 0.20$_{\text{sys}}$ and an exponential cut-off at
15.2$^{+5.5}_{-3.2}$ TeV, or a broken power-law with $\Gamma_{1}$ = 1.96 $\pm$
0.06$_{\text{stat}}$ $\pm$ 0.20$_{\text{sys}}$, $\Gamma_{2}$ = 3.59 $\pm$
0.69$_{\text{stat}}$ $\pm$ 0.20$_{\text{sys}}$ for energies below and above
$E_{\rm{br}}$ = 11.2 $\pm$ 2.7 TeV, respectively. The VHE flux from HESS
J1826$-$130 is contaminated by the extended emission of the bright, nearby
pulsar wind nebula (PWN), HESS J1825$-$137, particularly at the low end of the
energy spectrum. Leptonic scenarios for the origin of HESS J1826$-$130 VHE
emission related to PSR J1826$-$1256 are confronted by our spectral and
morphological analysis. In a hadronic framework, taking into account the
properties of dense gas regions surrounding HESS J1826$-$130, the source
spectrum would imply an astrophysical object capable of accelerating the parent
particle population up to $\gtrsim$200 TeV. Our results are also discussed in a
multiwavelength context, accounting for both the presence of nearby supernova
remnants (SNRs), molecular clouds, and counterparts detected in radio, X-rays,
and TeV energies.
