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Dupuy R, Bertin M, Féraud G, Romanzin C, Putaud T, Philippe L, Michaut X, Jeseck P, Cimino R, Baglin V, Fillion JH. X-Ray induced desorption and photochemistry in CO ice. Phys Chem Chem Phys 2021; 23:15965-15979. [PMID: 34308933 DOI: 10.1039/d1cp02670d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report an investigation of X-ray induced desorption of neutrals, cations and anions from CO ice. The desorption of neutral CO, by far the most abundant, is quantified and discussed within the context of its application to astrochemistry. The desorption of many different cations, including large cations up to the mass limit of the spectrometer, is observed. In contrast, the only desorbing anions detected are O- and C-. The desorption mechanisms of all these species are discussed with the aid of their photodesorption spectrum. The evolution of the X-ray absorption spectrum shows significant chemical modifications of the ice upon irradiation, which along with the desorption of large cations gives a new insight into X-ray induced photochemistry in CO ice.
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Affiliation(s)
- R Dupuy
- Sorbonne Université, Observatoire de Paris, Université PSL, CNRS, LERMA, F-75005, Paris, France.
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Herczku P, Mifsud DV, Ioppolo S, Juhász Z, Kaňuchová Z, Kovács STS, Traspas Muiña A, Hailey PA, Rajta I, Vajda I, Mason NJ, McCullough RW, Paripás B, Sulik B. The Ice Chamber for Astrophysics-Astrochemistry (ICA): A new experimental facility for ion impact studies of astrophysical ice analogs. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:084501. [PMID: 34470410 DOI: 10.1063/5.0050930] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 07/27/2021] [Indexed: 06/13/2023]
Abstract
The Ice Chamber for Astrophysics-Astrochemistry (ICA) is a new laboratory end station located at the Institute for Nuclear Research (Atomki) in Debrecen, Hungary. The ICA has been specifically designed for the study of the physico-chemical properties of astrophysical ice analogs and their chemical evolution when subjected to ionizing radiation and thermal processing. The ICA is an ultra-high-vacuum compatible chamber containing a series of IR-transparent substrates mounted on a copper holder connected to a closed-cycle cryostat capable of being cooled down to 20 K, itself mounted on a 360° rotation stage and a z-linear manipulator. Ices are deposited onto the substrates via background deposition of dosed gases. The ice structure and chemical composition are monitored by means of FTIR absorbance spectroscopy in transmission mode, although the use of reflectance mode is possible by using metallic substrates. Pre-prepared ices may be processed in a variety of ways. A 2 MV Tandetron accelerator is capable of delivering a wide variety of high-energy ions into the ICA, which simulates ice processing by cosmic rays, solar wind, or magnetospheric ions. The ICA is also equipped with an electron gun that may be used for electron impact radiolysis of ices. Thermal processing of both deposited and processed ices may be monitored by means of both FTIR spectroscopy and quadrupole mass spectrometry. In this paper, we provide a detailed description of the ICA setup as well as an overview of the preliminary results obtained and future plans.
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Affiliation(s)
- Péter Herczku
- Institute for Nuclear Research (Atomki), PO Box 51, Debrecen H-4026, Hungary
| | - Duncan V Mifsud
- Institute for Nuclear Research (Atomki), PO Box 51, Debrecen H-4026, Hungary
| | - Sergio Ioppolo
- School of Electronic Engineering and Computer Science, Queen Mary University of London, London E1 4NS, United Kingdom
| | - Zoltán Juhász
- Institute for Nuclear Research (Atomki), PO Box 51, Debrecen H-4026, Hungary
| | - Zuzana Kaňuchová
- Astronomical Institute, Slovak Academy of Sciences, Tatranská Lomnica SK-059 60, Slovakia
| | - Sándor T S Kovács
- Institute for Nuclear Research (Atomki), PO Box 51, Debrecen H-4026, Hungary
| | - Alejandra Traspas Muiña
- School of Electronic Engineering and Computer Science, Queen Mary University of London, London E1 4NS, United Kingdom
| | - Perry A Hailey
- Centre for Astrophysics and Planetary Science, School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom
| | - István Rajta
- Institute for Nuclear Research (Atomki), PO Box 51, Debrecen H-4026, Hungary
| | - István Vajda
- Institute for Nuclear Research (Atomki), PO Box 51, Debrecen H-4026, Hungary
| | - Nigel J Mason
- Centre for Astrophysics and Planetary Science, School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom
| | - Robert W McCullough
- Department of Physics and Astronomy, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, United Kingdom
| | - Béla Paripás
- Department of Physics, Faculty of Mechanical Engineering and Informatics, University of Miskolc, Miskolc H-3515, Hungary
| | - Béla Sulik
- Institute for Nuclear Research (Atomki), PO Box 51, Debrecen H-4026, Hungary
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The Disk Substructures at High Angular Resolution Project (DSHARP). II. Characteristics of Annular Substructures. ACTA ACUST UNITED AC 2018. [DOI: 10.3847/2041-8213/aaf740] [Citation(s) in RCA: 243] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Agúndez M, Roueff E, Le Petit F, Le Bourlot J. The chemistry of disks around T Tauri and Herbig Ae/Be stars. ASTRONOMY AND ASTROPHYSICS 2018; 616:A19. [PMID: 30185991 PMCID: PMC6120683 DOI: 10.1051/0004-6361/201732518] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
CONTEXT Infrared and (sub-)mm observations of disks around T Tauri and Herbig Ae/Be stars point to a chemical differentiation between both types of disks, with a lower detection rate of molecules in disks around hotter stars. AIMS To investigate the underlying causes of the chemical differentiation indicated by observations we perform a comparative study of the chemistry of T Tauri and Herbig Ae/Be disks. This is one of the first studies to compare chemistry in the outer regions of these two types of disks. METHODS We developed a model to compute the chemical composition of a generic protoplanetary disk, with particular attention to the photochemistry, and applied it to a T Tauri and a Herbig Ae/Be disk. We compiled cross sections and computed photodissociation and photoionization rates at each location in the disk by solving the FUV radiative transfer in a 1+1D approach using the Meudon PDR code and adopting observed stellar spectra. RESULTS The warmer disk temperatures and higher ultraviolet flux of Herbig stars compared to T Tauri stars induce some differences in the disk chemistry. In the hot inner regions, H2O, and simple organic molecules like C2H2, HCN, and CH4 are predicted to be very abundant in T Tauri disks and even more in Herbig Ae/Be disks, in contrast with infrared observations that find a much lower detection rate of water and simple organics toward disks around hotter stars. In the outer regions, the model indicates that the molecules typically observed in disks, like HCN, CN, C2H, H2CO, CS, SO, and HCO+, do not have drastic abundance differences between T Tauri and Herbig Ae disks. Some species produced under the action of photochemistry, like C2H and CN, are predicted to have slightly lower abundances around Herbig Ae stars due to a narrowing of the photochemically active layer. Observations indeed suggest that these radicals are somewhat less abundant in Herbig Ae disks, although in any case the inferred abundance differences are small, of a factor of a few at most. A clear chemical differentiation between both types of disks concerns ices. Owing to the warmer temperatures of Herbig Ae disks, one expects snowlines lying farther away from the star and a lower mass of ices compared to T Tauri disks. CONCLUSIONS The global chemical behavior of T Tauri and Herbig Ae/Be disks is quite similar. The main differences are driven by the warmer temperatures of the latter, which result in a larger reservoir or water and simple organics in the inner regions and a lower mass of ices in the outer disk.
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Affiliation(s)
- Marcelino Agúndez
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, E-28006 Madrid, Spain
| | - Evelyne Roueff
- Sorbonne Université, Observatoire de Paris, Université PSL, CNRS, LERMA, F-92190 Meudon, France
| | - Franck Le Petit
- Sorbonne Université, Observatoire de Paris, Université PSL, CNRS, LERMA, F-92190 Meudon, France
| | - Jacques Le Bourlot
- Sorbonne Université, Observatoire de Paris, Université PSL, CNRS, LERMA, F-92190 Meudon, France
- Université Paris-Diderot, Sorbonne Paris-Cité, F-75013 Paris, France
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Öberg KI. Photochemistry and Astrochemistry: Photochemical Pathways to Interstellar Complex Organic Molecules. Chem Rev 2016; 116:9631-63. [DOI: 10.1021/acs.chemrev.5b00694] [Citation(s) in RCA: 255] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Karin I. Öberg
- Harvard-Smithsonian Center for Astrophysics, 60
Garden St., Cambridge, Massachusetts 02138, United States
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Cleeves LI, Bergin EA, Alexander CMO, Du F, Graninger D, Öberg KI, Harries TJ. EXPLORING THE ORIGINS OF DEUTERIUM ENRICHMENTS IN SOLAR NEBULAR ORGANICS. THE ASTROPHYSICAL JOURNAL 2016; 819:13. [PMID: 30842682 PMCID: PMC6398959 DOI: 10.3847/0004-637x/819/1/13] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Deuterium-to-hydrogen (D/H) enrichments in molecular species provide clues about their original formation environment. The organic materials in primitive solar system bodies generally have higher D/H ratios and show greater D/H variation when compared to D/H in solar system water. We propose this difference arises at least in part due to (1) the availability of additional chemical fractionation pathways for organics beyond that for water, and (2) the higher volatility of key carbon reservoirs compared to oxygen. We test this hypothesis using detailed disk models, including a sophisticated, new disk ionization treatment with a low cosmic-ray ionization rate, and find that disk chemistry leads to higher deuterium enrichment in organics compared to water, helped especially by fractionation via the precursorsCH 2 D + / CH 3 + . We also find that the D/H ratio in individual species varies significantly depending on their particular formation pathways. For example, from ~20-40 au, CH4 can reach D/H ~ 2 × 10-3, while D/H in CH3OH remains locally unaltered. Finally, while the global organic D/H in our models can reproduce intermediately elevated D/H in the bulk hydrocarbon reservoir, our models are unable to reproduce the most deuterium-enriched organic materials in the solar system, and thus our model requires some inheritance from the cold interstellar medium from which the Sun formed.
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Affiliation(s)
- L Ilsedore Cleeves
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA;
| | - Edwin A Bergin
- Department of Astronomy, University of Michigan, 1085 S. University Avenue, Ann Arbor, MI 48109, USA
| | | | - Fujun Du
- Department of Astronomy, University of Michigan, 1085 S. University Avenue, Ann Arbor, MI 48109, USA
| | - Dawn Graninger
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA;
| | - Karin I Öberg
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA;
| | - Tim J Harries
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK
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The comet-like composition of a protoplanetary disk as revealed by complex cyanides. Nature 2015; 520:198-201. [PMID: 25855455 DOI: 10.1038/nature14276] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 01/30/2015] [Indexed: 11/09/2022]
Abstract
Observations of comets and asteroids show that the solar nebula that spawned our planetary system was rich in water and organic molecules. Bombardment brought these organics to the young Earth's surface. Unlike asteroids, comets preserve a nearly pristine record of the solar nebula composition. The presence of cyanides in comets, including 0.01 per cent of methyl cyanide (CH3CN) with respect to water, is of special interest because of the importance of C-N bonds for abiotic amino acid synthesis. Comet-like compositions of simple and complex volatiles are found in protostars, and can readily be explained by a combination of gas-phase chemistry (to form, for example, HCN) and an active ice-phase chemistry on grain surfaces that advances complexity. Simple volatiles, including water and HCN, have been detected previously in solar nebula analogues, indicating that they survive disk formation or are re-formed in situ. It has hitherto been unclear whether the same holds for more complex organic molecules outside the solar nebula, given that recent observations show a marked change in the chemistry at the boundary between nascent envelopes and young disks due to accretion shocks. Here we report the detection of the complex cyanides CH3CN and HC3N (and HCN) in the protoplanetary disk around the young star MWC 480. We find that the abundance ratios of these nitrogen-bearing organics in the gas phase are similar to those in comets, which suggests an even higher relative abundance of complex cyanides in the disk ice. This implies that complex organics accompany simpler volatiles in protoplanetary disks, and that the rich organic chemistry of our solar nebula was not unique.
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