IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2023A002 PROGRAM_TITLE Synoptic Observations of the Central star and Inner Nebular Regions of HD 44179 [Red Rectangle] and MWC 922 [Red Square]. PROGRAM_INV1 Michael Sitko PROGRAM_INV2 Ray Russell PROGRAM_INV3 PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG HD 44179 and MWC 922 are the central stars of the Red Rectangle and Red Square nebula, respectively. These display structures due to major ejection events on time scales of centuries. But both contain close binary stars. The orbital period of HD 44179 is ~200 days, while that of PWC 922. Both exhibit emission bands of organic species at 3-12 microns. Yet, the precise way these are formed is not known. Of the two, HD 44179 is better-studied, but synoptic IR spectroscopic observations on orbital time scales have yet to be obtained. The peak continuum brightness [in lF[l] W/m^2] is at 2.5 um, implying T[dust] ~1500 K. This is especially true for instruments capable of obtaining spectra st 3.3 um, as few instruments exist that can't spectra at that wavelength. SpeX LXD thus can make fundamental contributions to our understanding of the circumstellar regions where organics are produced. MWC 922 is virtually unexplored in this spectral region, but the similarity of the morphology of the Red Square to the Red Rectangle suggests a similar physical nature. The project proposed here with be the first step to obtain synoptic 1-5 micron spectra of these fascinating objects. PROGRAM_ABSTRACT_END