Detection of the hydroperoxyl radical HO2 toward ρOph A: Additional constraints on the water chemical network

Abstract

Context: Hydrogen peroxide (HOOH) was recently detected toward ρOph A. Subsequent astrochemical modeling that included reactions in the gas phase and on the surface of dust grains was able to explain the observed abundance, and highlighted the importance of grain chemistry in the formation of HOOH as an intermediate product in water formation. This study also predicted that the hydroperoxyl radical HO2, the precursor of HOOH, should be detectable. Aims: We aim at detecting the hydroperoxyl radical HO2 in ρOph A. Methods: We used the IRAM 30m and the APEX telescopes to target the brightest HO2 lines at about 130 and 260 GHz. Results: We detect five lines of HO2 (comprising seven individual molecular transitions). The fractional abundance of HO2 is found to be about 1e-10, a value similar to the abundance of HOOH. This observational result is consistent with the prediction of the above mentioned astrochemical model, and thereby validates our current understanding of the water formation on dust grains. Conclusions: This detection, anticipated by a sophisticated gas-grain chemical model, demonstrates that models of grain chemistry have improved tremendously and that grain surface reactions now form a crucial part of the overall astrochemical network.

arXiv comment5 pages, 4 figures, accepted for publication as a Letter to the Editor in Astronomy and Astrophysics

References in corpus (13)

• Detection of the Water Reservoir in a Forming Planetary System
• Water in Star-Forming Regions with the Herschel Space Observatory (WISH): Overview of key program and first results
• TIMASSS: The IRAS16293-2422 Millimeter And Submillimeter Spectral Survey. I. Observations, calibration and analysis of the line kinematics
• Water formation at low temperatures by surface O2 hydrogenation II: the reaction network
• Water formation at low temperatures by surface O2 hydrogenation I: characterization of ice penetration
• Detection of interstellar hydrogen peroxide
• Water cooling of shocks in protostellar outflows: Herschel-PACS map of L1157
• Multi-line detection of O2 toward rho Oph A
• Discovery of Interstellar CF+
• Deuterated formaldehyde in rho Ophiuchi A
• Production of interstellar hydrogen peroxide (H2O2) on the surface of dust grains
• Water vapor toward starless cores: the Herschel view
• A hybrid moment equation approach to gas-grain chemical modeling

Cited by in corpus (18)

• 2021 Census of Interstellar, Circumstellar, Extragalactic, Protoplanetary Disk, and Exoplanetary Molecules
• 2018 Census of Interstellar, Circumstellar, Extragalactic, Protoplanetary Disk, and Exoplanetary Molecules
• Interstellar water chemistry: from laboratory to observations
• Chemistry of Dark Clouds: Databases, Networks, and Models
• Astrochemistry of dust, ice and gas: introduction and overview
• A primordial origin for molecular oxygen in comets: A chemical kinetics study of the formation and survival of O${}_2$ ice from clouds to disks
• Parameterizing the interstellar dust temperature
• Volatile species in comet 67P/Churyumov-Gerasimenko -- investigating the link from the ISM to the terrestrial planets
• Dust as interstellar catalyst - II. How chemical desorption impacts the gas
• The effect of selective desorption mechanisms during interstellar ice formation
• Gas and dust in the star-forming region rho Oph A: II. The gas in the PDR and in the dense cores
• Influence of galactic arm scale dynamics on the molecular composition of the cold and dense ISM II. Molecular oxygen abundance
• Implementation of Rare Isotopologues into Machine Learning of the Chemical Inventory of the Solar-Type Protostellar Source IRAS 16293-2422
• Characterizing the chemical pathways for water formation -- A deep search for hydrogen peroxide
• Search for HOOH in Orion
• First detection of HS2 in a cold dark cloud
• Deep search for hydrogen peroxide toward pre- and protostellar objects -- Testing the pathway of grain surface water formation
• Kinetic Study of the Reactions of Ground State Atomic Carbon and Oxygen with Nitrogen Dioxide over the 50-296 K Temperature Range