  We present the first observational evidence of multiple slow acoustic
oscillations in the post flaring loops of the corona of Proxima Centauri using
XMM-Newton observations. We find the signature of periodic oscillations
localized in the decay phase of the flare in its soft (0.3-10.0 keV) X-ray
emissions. Using the standard wavelet tool, we find the multiple periodicities
of 1261 s and 687 s. These bursty oscillations persist for durations of 90
minutes and 50 minutes, respectively, for more than 4 cycles. The intensity
oscillations with the period of 1261 s may be the signature of the fundamental
mode of slow magnetoacoustic waves with the phase-speed of 119 km s$^{-1}$ in
the loop of the length 7.5$\times 10^{9}$ cm heated initially to obtain the
flare peak temperature of 33 MK and later cooled down in the decay phase
maintained at the average temperature of 7.2 MK. The other period of 687 s may
be associated with the first overtone of slow magnetoacoustic oscillations in
the flaring loop. The fundamental mode oscillations show a dissipation with
damping time of 47 min. The period ratio P$_{1}$/P$_{2}$ is found to be 1.83
indicating that such oscillations are most likely excited in longitudinal
density stratified stellar loops. We estimate the density scale height of
stellar loop system as 22.6 Mm, which is smaller than the hydrostatic scale
height of the hot loop system, and implies the existence of non-equilibrium
conditions.
