A SURVEY OF LARGE MOLECULES TOWARD THE PROTOPLANETARY NEBULA CRL 618

Abstract

We present the results of our survey toward the protoplanetary nebula CRL 618 for several large, highly saturated, oxygen bearing organic molecules of biological importance including acetaldehyde (CH$_3$CHO), acetic acid (CH$_3$COOH), dimethyl ether (CH$_3$OCH$_3$), ethanol (CH$_3$CH$_2$OH), formic acid (HCOOH) and methyl formate (HCOOCH$_3$); large carbon chain molecules including methyl cyanide (CH$_3$CN), methylcyanoacetylene (CH$_3$C$_3$N), cyanoacetylene (HC$_3$N), cyanodiacetylene (HC$_5$N), and C$_6$H; and finally smaller molecules including $^{34}$SO, SO$_2$, OC$^{34}$S and MgNC. No biologically important organic molecules were detected. However, we report the first interferometric detections of CH$_3$CN and vibrationally excited HC$_3$N and HC$_5$N toward this source. Also, we compare the upper limits of the column densities of the molecular species that were not detected to the predicted column densities based on gas phase formation models.