# L1157-B1, a factory of complex organic molecules in a Solar-type star forming region

## TL;DR

This study uncovers a variety of complex organic molecules in the star-forming region L1157-B1, revealing new detections and insights into their formation, using high-sensitivity spectral observations and analysis.

## Contribution

First systematic detection of multiple COMs in L1157-B1, including new molecules, with detailed analysis of their excitation and potential formation pathways.

## Key findings

- Detection of several COMs, including first-time detections of ketene, dimethyl ether, and glycolaldehyde.
- Strong correlation between ethanol, methanol, and glycolaldehyde abundances.
- Derived excitation conditions and column densities for the detected molecules.

## Abstract

We report on a systematic search for oxygen-bearing Complex Organic Molecules (COMs) in the Solar-like protostellar shock region L1157-B1, as part of the IRAM Large Program "Astrochemical Surveys At IRAM" (ASAI). Several COMs are unambiguously detected, some for the first time, such as ketene H$_2$CCO, dimethyl ether (CH$_3$OCH$_3$) and glycolaldehyde (HCOCH$_2$OH), and others firmly confirmed, such as formic acid (HCOOH) and ethanol (C$_2$H$_5$OH). Thanks to the high sensitivity of the observations and full coverage of the 1, 2 and 3mm wavelength bands, we detected numerous (10--125) lines from each of the detected species. Based on a simple rotational diagram analysis, we derive the excitation conditions and the column densities of the detected COMs. Combining our new results with those previously obtained towards other protostellar objects, we found a good correlation between ethanol, methanol and glycolaldehyde. We discuss the implications of these results on the possible formation routes of ethanol and glycolaldehyde.