Evolutionary study of complex organic molecules in high-mass star-forming regions

Coletta, Alessandro; Fontani, F.; Rivilla, V. M.; Mininni, C.; Colzi, L.; Sánchez-Monge, Á.; Beltrán, M. T.

doi:10.1051/0004-6361/202038212

Cited by 49 publications

(27 citation statements)

References 156 publications

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“…The enhancement of COMs in low-mass Class 0 and Class I protostars is illustrated in Figure 12, and is a trend that has been seen before (e.g., López-Sepulcre et al (2017)). In a process laid out recently by Coletta et al (2020), who observed this same trend in a large sample of massive star-forming regions, molecular abundance will increase through thermal or shock induced desorption of COMs, first formed on ices.…”

Section: )mentioning

confidence: 59%

Detection of Complex Organic Molecules in Young Starless Core L1521E

Scibelli,

Shirley,

Vasyunin

et al. 2021

Preprint

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Determining the level of chemical complexity within dense starless and gravitationally bound prestellar cores is crucial for constructing chemical models, which subsequently constrain the initial chemical conditions of star formation. We have searched for complex organic molecules (COMs) in the young starless core L1521E, and report the first clear detection of dimethyl ether (CH 3 OCH 3 ), methyl formate (HCOOCH 3 ), and vinyl cyanide (CH 2 CHCN). Eight transitions of acetaldehyde (CH 3 CHO) were also detected, five of which (A states) were used to determine an excitation temperature to then calculate column densities for the other oxygen-bearing COMs. If source size was not taken into account (i.e., if filling fraction was assumed to be one), column density was underestimated, and thus we stress the need for higher resolution mapping data. We calculated L1521E COM abundances and compared them to other stages of low-mass star formation, also finding similarities to other starless/prestellar cores, suggesting related chemical evolution. The scenario that assumes formation of COMs in gas-phase reactions between precursors formed on grains and then ejected to the cold gas via reactive desorption was tested and was unable to reproduce observed COM abundances, with the exception of CH 3 CHO. These results suggest that COMs observed in cold gas are formed not by gas-phase reactions alone, but also through surface reactions on interstellar grains. Our observations present a new, unique challenge for existing theoretical astrochemical models.

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Section: )mentioning

confidence: 59%

Detection of Complex Organic Molecules in Young Starless Core L1521E

Scibelli,

Shirley,

Vasyunin

et al. 2021

Preprint

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“…However, the mean values of observed abundances show an increase of one order of magnitude among HMSCs and more evolved sources, but no clear distinction between HMPOs and UC HII regions in the TOPGöt sample. An increase in abundances with evolutionary stages has been found by Coletta et al (2020) for other COMS such as methyl formate, dimethyl ether and ethyl cyanide, and it is a powerful tool to infer the evolutionary stage of a source without performing a multi-wavelength analysis. -From the comparison of values of X CH 3 CN in already classified sources of the Sub-sample I, we found five good candidates of HMSCs or very early HMPOs in Sub-sample II.…”

Section: Discussionmentioning

confidence: 98%

“…A small part of the observations towards these sources has already been analyzed and published in previous works covering different topics, from deuteration in selected molecules (N 2 H + , CH 3 OH, NH 3 , HC 3 N; Fontani et al 2011Fontani et al , 2015aRivilla et al 2020), to nitrogen fractionation of HCN, HNC and N 2 H + (Fontani et al 2015b;Colzi et al 2018a), to prebiotic and complex organic molecules (COMs, Mininni et al 2018;Coletta et al 2020).…”

Section: Selection Criteria For Hmpos and Uc Hii Regionsmentioning

confidence: 99%

The TOPGöt high-mass star-forming sample. I. Methyl cyanide emission as tracer of early phases of star formation

Mininni,

Fontani,

Sánchez-Monge

et al. 2021

Preprint

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Aims. The TOPGöt project studies a sample of 86 high-mass star-forming regions in different evolutionary stages from starless cores to ultra compact HII regions. The aim of the survey is to analyze different molecular species in a statistically significant sample to study the chemical evolution in high-mass star-forming regions, and identify chemical tracers of the different phases. Methods. The sources have been observed with the IRAM 30m telescope in different spectral windows at 1, 2, and 3 mm. In this first paper, we present the sample and analyze the spectral energy distributions (SEDs) of the TOPGöt sources to derive physical parameters such as the dust temperature, T dust , the total column density, N H 2 , the mass, M, the luminosity, L, and the luminosity-tomass ratio, L/M, an indicator of the evolutionary stage of the sources. We use the MADCUBA software to analyze the emission of methyl cyanide (CH 3 CN), a well-known tracer of high-mass star formation. . Results. We built the spectral energy distributions for ∼ 80% of the sample and derived T dust and N H 2 values which range between 9 − 36 K and ∼ 3 × 10 21 − 7 × 10 23 cm −2 , respectively. The luminosity of the sources spans over four orders of magnitude from 30 to 3 × 10 5 L , masses vary between ∼ 30 and 8 × 10 3 M , and the luminosity-to-mass ratio L/M covers three orders of magnitude from 6 × 10 −2 to 3 × 10 2 L /M . The emission of the CH 3 CN(5 K − 4 K ) K-transitions has been detected towards 73 sources (85% of the sample), with 12 non-detections and one source not observed in the frequency range of CH 3 CN(5 K − 4 K ). The emission of CH 3 CN has been detected towards all evolutionary stages, with the mean abundances showing a clear increase of an order of magnitude from high-mass starless-cores to later evolutionary stages. We found a conservative abundance upper limit for high-mass starless cores of X CH 3 CN < 4.0 × 10 −11 , and a range in abundance of 4.0 × 10 −11 < X CH 3 CN < 7.0 × 10 −11 for those sources that are likely high-mass starless cores or very early high-mass protostellar objects. In fact, in this range of abundance we have identified five sources previously not classified as being in a very early evolutionary stage. The abundance of CH 3 CN can thus be used to identify high-mass star-forming regions in early phases of star-formation.

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“…There are well-known hot cores in the molecular clouds of Sgr B2 and Orion [71][72][73][74][75] while IRAS 16293-2422, NGC1333 IRAS2A, IRAS4A and IRAS4B were the first discovered hot corinos. 14,58,[76][77][78] With low mass protostars, there is also evidence for sublimation fronts. For instance, the sublimation radius for the more volatile CO is observed to be located at larger radii than that of water and other more complex species 79,80 .…”

Section: Excitation Temperaturesmentioning

confidence: 99%

Thermal desorption of interstellar ices. A review on the controlling parameters and their implications fromsnowlines to chemical complexity

Minissale¹,

Aikawa²,

Bergin³

et al. 2022

Preprint

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The evolution of star-forming regions and their thermal balance are strongly influenced by their chemical composition, that, in turn, is determined by the physicochemical processes that govern the transition between the gas phase and the solid state, specifically icy dust grains (e.g., particles adsorption and desorption). Gas-grain and grain-gas transitions as well as formation and sublimation of interstellar ices are thus essential elements of understanding astrophysical observations of cold environments (e.g., pre-stellar cores) where unexpected amounts of a large variety of chemical species have been observed in the gas phase. Adsorbed atoms and molecules also undergo chemical reactions which are not efficient in the gas phase. Therefore the parameterization of the physical properties of atoms and molecules interacting with dust grain particles is clearly a key aspect to interpret astronomical observations and to build realistic and predictive astrochemical models. In this consensus evaluation, we focus on parameters controlling the thermal desorption of ices and how these determine pathways towards molecular complexity and define the location of snowlines, which ultimately influence the planet formation process.We review different crucial aspects of desorption parameters both from a theoretical and experimental point of view. We critically assess the desorption parameters (the binding energies E b and the pre-exponential factor ν) commonly used in the astrochemical community for astrophysically relevant species and provide tables with recommended values. The aim of these tables is to provide a coherent set of critically assessed desorption parameters for common use in future work. In addition, we show that a non-trivial determination of the pre-exponential factor ν using the Transition State Theory can affect the binding energy value. The primary focus is on pure ices, but we also discuss the desorption behavior of mixed, i.e. astronomically more realistic ices. This allows discussion of segregation effects. Finally, we conclude this work by discussing the limitations of theoretical and experimental approaches currently used to determine the desorption properties with suggestions for future improvements.

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Evolutionary study of complex organic molecules in high-mass star-forming regions

Cited by 49 publications

References 156 publications

Detection of Complex Organic Molecules in Young Starless Core L1521E

Detection of Complex Organic Molecules in Young Starless Core L1521E

The TOPGöt high-mass star-forming sample. I. Methyl cyanide emission as tracer of early phases of star formation

Thermal desorption of interstellar ices. A review on the controlling parameters and their implications fromsnowlines to chemical complexity

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