Exploring the formation pathways of formamide

Near young O-type stars^★

¹ NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, USA
e-mail: veronica.a.allen@nasa.gov
² Kapteyn Astronomical Institute, University of Groningen, Landleven 12, 9747 AD Groningen, The Netherlands
³ SRON, Landleven 12, 9747 AD Groningen, The Netherlands
⁴ CNRS, IPAG, Univ. Grenoble Alpes, 38000 Grenoble, France
⁵ IRAM, 300 rue de la Piscine, 38406 Saint-Martin d’Hères, France
⁶ I. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany
⁷ INAF, Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Florence, Italy

Received: 27 April 2019
Accepted: 18 December 2019

Abstract

Context. As a building block for amino acids, formamide (NH₂CHO) is an important molecule in astrobiology and astrochemistry, but its formation path in the interstellar medium is not understood well.

Aims. We aim to find empirical evidence to support the chemical relationships of formamide to HNCO and H₂CO.

Methods. We examine high angular resolution (~0.2″) Atacama Large Millimeter/submillimeter Array maps of six sources in three high-mass star-forming regions and compare the spatial extent, integrated emission peak position, and velocity structure of HNCO and H₂CO line emission with that of NH₂CHO by using moment maps. Through spectral modeling, we compare the abundances of these three species.

Results. In these sources, the emission peak separation and velocity dispersion of formamide emission is most often similar to HNCO emission, while the velocity structure is generally just as similar to H₂CO and HNCO (within errors). From the spectral modeling, we see that the abundances between all three of our focus species are correlated, and the relationship between NH₂CHO and HNCO reproduces the previously demonstrated abundance relationship.

Conclusions. In this first interferometric study, which compares two potential parent species to NH₂CHO, we find that all moment maps for HNCO are more similar to NH₂CHO than H₂CO in one of our six sources (G24 A1). For the other five sources, the relationship between NH₂CHO, HNCO, and H₂CO is unclear as the different moment maps for each source are not consistently more similar to one species as opposed to the other.