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Using $0.2^{\prime \prime}$ ($\sim3$ pc) ALMA images of vibrationally excitedHC$_3$N emission (HC$_3$N$^*$) we reveal the presence of $8$ unresolved SuperHot Cores (SHCs) in the inner $160$ pc of NGC\,253. Our LTE and non-LTEmodelling of the HC$_3$N$^*$ emission indicate that SHCs have dust temperaturesof $200-375$ K, relatively high H$_2$ densities of $1-6\times 10^{6}$ cm$^{-3}$and high IR luminosities of $0.1-1\times 10^8$ L$_\odot$. As expected fromtheir short lived phase ($\sim 10^4$ yr), all SHCs are associated with youngSuper Star Clusters (SSCs). We use the ratio of luminosities form the SHCs(protostar phase) and from the free-free emission (ZAMS star phase), toestablish the evolutionary stage of the SSCs. The youngest SSCs, with thelarges ratios, have ages of a few $10^4$ yr (proto-SSCs) and the more evolvedSSCs are likely between $10^5$ and $10^6$ yr (ZAMS-SSCs). The differentevolutionary stages of the SSCs are also supported by the radiative feedbackfrom the UV radiation as traced by the HNCO/CS ratio, with this ratio beingsystematically higher in the young proto-SSCs than in the older ZAMS-SSCs. Wealso estimate the SFR and the SFE of the SSCs. The trend found in the estimatedSFE ($\sim40\%$ for proto-SSCs and $>85\%$ for ZAMS-SSCs) and in the gas massreservoir available for star formation, one order of magnitude higher forproto-SSCs, suggests that star formation is still going on in proto-SSCs. Wealso find that the most evolved SSCs are located, in projection, closer to thecenter of the galaxy than the younger proto-SSCs, indicating an inside-out SSCformation scenario.

Super Hot Cores in NGC 253: Witnessing the formation and early evolution of Super Star Clusters