2010ApJ...716..286S

Acetic acid (CH₃COOH) has been detected mainly in hot molecular cores where the distribution between oxygen (O) and nitrogen (N) containing molecular species is cospatial within the telescope beam. Previous work has presumed that similar cores with cospatial O and N species may be an indicator for detecting acetic acid. However, does this presumption hold as higher spatial resolution observations of large O- and N-containing molecules become available? As the number of detected acetic acid sources is still low, more observations are needed to support this postulate. In this paper, we report the first acetic acid survey conducted with the Combined Array for Research in Millimeter-wave Astronomy at 3 mm wavelengths toward G19.61-0.23, G29.96-0.02, and IRAS 16293-2422. We have successfully detected CH₃ COOH via two transitions toward G19.61-0.23 and tentatively confirmed the detection toward IRAS 16293-2422 A. The determined column density of CH₃ COOH is 2.0(1.0)x10¹⁶/cm2 and the abundance ratio of CH₃ COOH to methyl formate (HCOOCH₃) is 2.2(0.1)x10^–1 toward G19.61-0.23. Toward IRAS 16293 A, the determined column density of CH₃COOH is ∼1.6x10¹⁵/cm2 and the abundance ratio of CH₃ COOH to methyl formate (HCOOCH₃) is ∼1.0x10^–1, both of which are consistent with abundance ratios determined toward other hot cores. Finally, we model all known line emission in our passband to determine physical conditions in the regions and introduce a new metric to better reveal weak spectral features that are blended with stronger lines or that may be near the 1σ-2σ detection limit.