Observations of Complex Molecules in Low-Mass Protostars

Abstract

Abstract. Low-mass star forming regions are rich inventories of complex organic molecules. Furthermore, they show significant chemical diversity even among sources in a similar physical evolutionary stage (i.e. Class 0 sources). One distinct case is the hot corino chemistry characterized by rich existence of saturated complex organic molecules such as HCOOCH3 and C2 H5 CN, whereas the other is the warm carbon-chain chemistry (WCCC) characterized by extraordinary richness of unsaturated complex organic molecules such as carbon-chain molecules. We here summarize these observational achievements during the last decade, and present a unified picture of carbon chemistry in low-mass protostellar cores. The chemical diversity most likely originates from the source-to-source difference in chemical compositions of grain mantles. In particular, the gas-phase abundance of CH 4 evaporated from grain mantles is thought to be a key factor for appearance of WCCC. The origin of the diversity and its evolution to protopranetary disks are discussed.

Warm Carbon-Chain Chemistry

“…After the birth of a protostar, the temperature starts to rise. We define the following three major steps in carbon chemistry:…”

“…On the other hand, large saturated COMs are not detected, indicating that the hot corino activity is very weak. Reprinted with permission from ref . Copyright 2011 International Astronomical Union.…”