The Origin of Complex Organic Molecules in Prestellar Cores

摘要: Complex organic molecules (COMs) have been detected in a variety of environments including cold prestellar cores. Given the low temperatures these objects, detections challenge existing models. We report here new observations toward core L1544. They are based on an unbiased spectral survey 3 mm band at IRAM 30 m telescope as part Large Program ASAI. The allow us to provide full census oxygen-bearing COMs this source. tricarbon monoxide, methanol, acetaldehyde, formic acid, ketene, and propyne with abundances varying from 5 × 10{sup –11} 6 –9}. non-LTE analysis methanol lines shows that they likely emitted border radius ∼8000 AU, where T ∼ 10 K n {sub H{sub 2}} ∼2 4} cm{sup –3}. Previous works shown water vapor is enhanced same region because photodesorption ices. propose non-thermal desorption mechanism also responsible for observed emission layer. desorbed oxygen small amount ethene enough reproduce themore » ketene measured These findings open possibility cores originate similar outer layer rather than dense inner cores, previously assumed, their formation driven by non-thermally species.« less