Gas-phase production of complex hydrocarbons, cyanopolyynes, and related compounds in dense interstellar clouds

Herbst, Eric; Leung, Cynthia

doi:10.1086/191314

Cited by 292 publications

(157 citation statements)

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“…Bruhns et al (2010), Brunetti & Liuti (1975) Harada & Herbst (2008), Harrison et al (1986), Hasegawa & Herbst (1993), Hawley et al (1990), Hemsworth et al (1974), Herbst (1983), Herbst et al (1984), Herbst & Leung (1986), Herbst et al (1989a), Herbst & Leung (1989), Herbst et al (1989b), Herbst et al (1989c), Herbst & Leung (1990), Herbst et al (2000), Herbst & Osamura (2008), Herbst et al (2010), Herrero et al (2010), Hoobler & Leone (1997), Huo et al (2011), Iglesias (1977, Inomata & Washida (1999), Johnson et al (2000), , Kalhori et al (2002), Kamińska et al (2008), Kern et al (1988), Wakelam et al (2012), Klippenstein et al (2010), Kuan et al (1999) Millar et al (1985), Millar et al (1986), Millar et al (1987), Millar et al (1988), Millar & Herbst (1990), Millar (1991, Millar et al (1991), Millar et al (1997b), Millar et al (2000), Millar et al (2007), Mi...…”

Section: Appendix A: Rate12 Referencesmentioning

confidence: 99%

The UMIST database for astrochemistry 2012

McElroy

Walsh

Markwick

et al. 2013

A&A

909

880

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We present the fifth release of the UMIST Database for Astrochemistry (UDfA). The new reaction network contains 6173 gas-phase reactions, involving 467 species, 47 of which are new to this release. We have updated rate coefficients across all reaction types. We have included 1171 new anion reactions and updated and reviewed all photorates. In addition to the usual reaction network, we also now include, for download, state-specific deuterated rate coefficients, deuterium exchange reactions and a list of surface binding energies for many neutral species. Where possible, we have referenced the original source of all new and existing data. We have tested the main reaction network using a dark cloud model and a carbon-rich circumstellar envelope model. We present and briefly discuss the results of these models.

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Section: Appendix A: Rate12 Referencesmentioning

confidence: 99%

The UMIST database for astrochemistry 2012

McElroy

Walsh

Markwick

et al. 2013

A&A

909

880

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“…This is the start of the C ϩ /C/CO transition zone. Neutralization of C ϩ through charge transfer with atomic S becomes a dominant source of C. Eventually, PDR chemistry gives way to standard dark-cloud, ionmolecule chemistry (Prasad and Huntress, 1980;Herbst and Leung, 1989 The transition from C ϩ to CO occurs in PDRs, and CO is used to trace molecular gas in the Galaxy (see Sec. VI.B.3).…”

Section: Pdr Chemical Network a Oxygen And Carbonmentioning

confidence: 99%

Photodissociation regions in the interstellar medium of galaxies

Hollenbach

Tielens²

1999

Rev. Mod. Phys.

756

712

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The interstellar medium of galaxies is the reservoir out of which stars are born and into which stars inject newly created elements as they age. The physical properties of the interstellar medium are governed in part by the radiation emitted by these stars. Far-ultraviolet (6 eVϽh Ͻ13.6 eV) photons from massive stars dominate the heating and influence the chemistry of the neutral atomic gas and much of the molecular gas in galaxies. Predominantly neutral regions of the interstellar medium in which the heating and chemistry are regulated by far ultraviolet photons are termed PhotoDissociation Regions (PDRs). These regions are the origin of most of the non-stellar infrared (IR) and the millimeter and submillimeter CO emission from galaxies. The importance of PDRs has become increasingly apparent with advances in IR and submillimeter astronomy. The IR emission from PDRs includes fine structure lines of C, C ϩ , and O; rovibrational lines of H 2 ; rotational lines of CO; broad mid-IR features of polycyclic aromatic hydrocarbons; and a luminous underlying IR continuum from interstellar dust. The transition of H to H 2 and C ϩ to CO occurs within PDRs. Comparison of observations with theoretical models of PDRs enables one to determine the density and temperature structure, the elemental abundances, the level of ionization, and the radiation field. PDR models have been applied to interstellar clouds near massive stars, planetary nebulae, red giant outflows, photoevaporating planetary disks around newly formed stars, diffuse clouds, the neutral intercloud medium, and molecular clouds in the interstellar radiation field-in summary, much of the interstellar medium in galaxies. Theoretical PDR models explain the observed correlations of the [CII] 158 m with the CO Jϭ1 -0 emission, the CO Jϭ1 -0 luminosity with the interstellar molecular mass, and the [CII] 158 m plus [OI] 63 m luminosity with the IR continuum luminosity. On a more global scale, PDR models predict the existence of two stable neutral phases of the interstellar medium, elucidate the formation and destruction of star-forming molecular clouds, and suggest radiation-induced feedback mechanisms that may regulate star formation rates and the column density of gas through giant molecular clouds. [S0034-6861(99)01001-6] CONTENTS

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“…Harada et al 2013), carbon-rich protostellar objects (e.g. Cordiner et al 2012Cordiner et al , 2014Gupta et al 2009;Sakai et al 2009), interstellar clouds (Duley & Hu 2009;Cernicharo et al 1984;Herbst & Leung 1989), and objects in the solar system, such as comets (Cordiner et al 2014) and Uranus (Burgdorf et al 2006). A special mention goes to the atmosphere of Titan where the photolysis of a methane plus hydrogen mixture induces a plethora of chemical reactions that lead to the formation of polyynes (Smith et al 1998), which are also involved in the formation of the UV haze (Hunten 2006).…”

Section: Astrophysical Implicationsmentioning

confidence: 99%

Vacuum ultraviolet photochemistry of solid acetylene: a multispectral approach

Cuylle

Zhao

Strazzulla

et al. 2014

A&A

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Aims. Gas phase acetylene (C 2 H 2 ) and polyynes (H(-C≡C-) m H) are ubiquitous in the interstellar medium. However, astrochemical models systematically underestimate the observed abundances, supporting the idea that enrichment from the solid state takes place. In this laboratory-based study, we investigate the role C 2 H 2 plays in interstellar ice chemistry and we discuss the way its photoproducts may affect gas phase compositions. Methods. C 2 H 2 ice is investigated under vacuum ultraviolet (VUV) irradiation in its pure form as present in the atmosphere of Titan and in a water-dominated ice as present on grain mantles in molecular clouds and on comets. To disentangle the photochemical network, a unique, complementary combination of infrared and ultraviolet-visible (UV-VIS) spectroscopy is used. Results. From the experimental results, it can be concluded that the VUV-induced solid state C 2 H 2 reaction network is dominated by polymerization resulting in the formation of polyynes at least up to C 20 H 2 and larger polyyne-like molecules. At low temperatures, this process takes place very efficiently and suggests low barriers. When extending this reaction scheme to a water-rich environment, the dominant reaction products are CO and CO 2 but the simultaneous detection of polyyne like molecules is evidence that the reactions as observed in pure C 2 H 2 ice persist. Conclusions. From the spectroscopic evidence as presented in this laboratory study, it is concluded that the formation of polyynes upon VUV irradiation of interstellar ices is a process that may contribute to at least part of the observed gas phase enrichment in space.

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Gas-phase production of complex hydrocarbons, cyanopolyynes, and related compounds in dense interstellar clouds

Cited by 292 publications

References 0 publications

The UMIST database for astrochemistry 2012

The UMIST database for astrochemistry 2012

Photodissociation regions in the interstellar medium of galaxies

Vacuum ultraviolet photochemistry of solid acetylene: a multispectral approach

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