Knowledge Bank

We have used the Combined Array for Research in Millimeter-wave Astronomy (CARMA) to conduct a survey of acetic acid (CH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$COOH) at 3 mm wavelengths toward the hot core G19.61-0.23 and the two deeply embedded low-mass protostars IRAS 16293-2422 and NGC 1333 IRAS 4. The observed CH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$COOH transitions are the $10\ast ,10-9\ast ,9$ E and A lines. We have detected ($>$3 $\sigma$ level) these two lines in G19.61-0.23. The abundance ratio of CH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$COOH to its isomer, methyl formate (HCOOCH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$), is comparable to other CH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$COOH sources. However, the CH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$COOH lines in IRAS 16293-2422 and NGC 1333 IRAS 4 are not detected in our observations. We set upper limits for the column densities for each source. Based on the CH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$COOH detection in IRAS 16293-2422 reported by Cazaux et al., we should have detected the two lines. Therefore, we suggest that the CH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$COOH detection in IRAS 16293-2422 is still uncertain. \vspace{0.1in} We acknowledge support from the Laboratory for Astronomical Imaging at the University of Illinois and NSF grant AST-0540459.