NGC 2024: excitation of the dense cores

Measurements of CS and C 34 S J=7-6 toward five of the six millimetre continuum sources in NGC 2024 were used to estimate the excitation temperatures and column densities of warm, dense gas associated with the cores. For estimated CS source sizes of ∼20 arcsec, the calculated excitation temperatures are ≥24 K, consistent with previous studies. A correlation between CS column density and hydrogen column density derived from the thermal dust continuum shows that it is self-consistent to assume internally heated cores and a close relationship between the characteristic temperatures of the CS-traced gas and the dust traced by the millimetre continuum. The nature of the individual sources is also discussed