The ALMA-PILS survey: Complex nitriles towards IRAS 16293--2422
Langue
en
Article de revue
Ce document a été publié dans
Astronomy and Astrophysics - A&A. 2018, vol. 616, p. A90
EDP Sciences
Résumé en anglais
Complex organic molecules are readily detected in the inner regions of the gaseous envelopes of forming protostars. In particular, molecules that contain nitrogen are interesting due to the role nitrogen plays in the ...Lire la suite >
Complex organic molecules are readily detected in the inner regions of the gaseous envelopes of forming protostars. In particular, molecules that contain nitrogen are interesting due to the role nitrogen plays in the development of life and the compact scales such molecules have been found to trace around forming protostars. The goal of this work is to determine the inventory of one family of nitrogen-bearing organic molecules, complex nitriles (molecules with a $-$CN functional group) towards two hot corino sources in the low-mass protostellar binary IRAS 16293$-$2422. This work explores the abundance differences between the two sources, the isotopic ratios, and the spatial extent derived from molecules containing the nitrile functional group. Using data from the Protostellar Interferometric Line Survey (PILS) obtained with ALMA we determine abundances and excitation temperatures for the detected nitriles. We also present a new method for determining the spatial structure of sources with high line density and large velocity gradients $-$ Velocity-corrected INtegrated emission (VINE) maps. We detect methyl cyanide (CH$_3$CN) as well as 5 of its isotopologues, including the detection of CHD$_2$CN which is the first detection in the ISM. We also detect ethyl cyanide (C$_2$H$_5$CN), vinyl cyanide (C$_2$H$_3$CN), and cyanoacetylene (HC$_3$N). We find that abundances are similar between IRAS 16293A and IRAS 16293B on small scales except for vinyl cyanide which is only detected towards the latter source. This suggests an important difference between the sources either in their evolutionary stage or warm-up timescales. We also detect a spatially double-peaked emission for the first time in molecular emission in the A source, suggesting that this source is showing structure related to a rotating toroid of material.< Réduire
Mots clés en anglais
Astrophysics - Astrophysics of Galaxies
Astrophysics - Solar and Stellar Astrophysics
Origine
Importé de halUnités de recherche