The Search for 11.7 Micron Sources in NGC 2023 and NGC 2024

by Marc James Pouilly

Under the supervision of Professor Leonard V. Kuhi

ABSTRACT

The K-band survey of NGC 2023 by Depoy, Lada, Gately and Probst (1990) showed a lack of stars fainter that K=12 mag. From an extrapolation of the Salpeter IMF, they predicted that 50 additional stars of spectral type G through K should have been detected. They proposed that the lack of these stars suggests either no low mass stars have formed or that the low mass stars are still heavily enshrouded in their molecular cocoons. Since out 11.7 micron survey did not go faint enough, we cannot determine which explanation is correct. However, we can conclude that the missing stars, if they are enshrouded, do not correspond to the precursors of G or K type stars. Rather, the enshrouded stars must be less massive than a 0.4 solar mass pre-main sequence star. This still leaves in doubt why the dense molecular gas core of NGC 2023 is so much less efficient at forming stars than that of NGC 2024, even thought they are nearly the same mass.