Submillimeter absorption from SH+, a new widespread interstellar radical,13CH+and HCl

Menten, K. M.; Wyrowski, F.; Беллоче, А.; Güsten, R.; Dedes, L.; Müller, H. S. P.

doi:10.1051/0004-6361/201014363

Cited by 118 publications

(115 citation statements)

References 104 publications

(124 reference statements)

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“…The physics of interstellar turbulence is not yet understood from first principles, however, and non-Maxwellian motions between ions and neutrals need to be taken into account in the presence of magnetic fields. Similarly, the formation of SH + , detected both with ground-based telescopes and with Herschel-HIFI, requires extra energy for the S + + H 2 reaction (+9860 K) to proceed 108,169 . Both species have somewhat larger line widths than those of CH and CN, ∼4 vs ∼2 km s −1 , further justifying that additional physical processes need to be invoked to drive the reactions.…”

Section: Diffuse and Translucent Cloudsmentioning

confidence: 99%

Astrochemistry of dust, ice and gas: introduction and overview

Dishoeck

Ewine²

2014

Faraday Discuss.

136

102

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A brief introduction and overview of the astrochemistry of dust, ice and gas and their interplay is presented, aimed at non-specialists. The importance of basic chemical physics studies of critical reactions is illustrated through a number of recent examples. Such studies have also triggered new insight into chemistry, illustrating how astronomy and chemistry can enhance each other. Much of the chemistry in star- and planet-forming regions is now thought to be driven by gas-grain chemistry rather than pure gas-phase chemistry, and a critical discussion of the state of such models is given. Recent developments in studies of diffuse clouds and PDRs, cold dense clouds, hot cores, protoplanetary disks and exoplanetary atmospheres are summarized, both for simple and more complex molecules, with links to papers presented in this volume. In spite of many lingering uncertainties, the future of astrochemistry is bright: new observational facilities promise major advances in our understanding of the journey of gas, ice and dust from clouds to planets.Comment: Introductory paper for Faraday Discussions 168 conference, April 201

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Section: Diffuse and Translucent Cloudsmentioning

confidence: 99%

Astrochemistry of dust, ice and gas: introduction and overview

Dishoeck

Ewine²

2014

Faraday Discuss.

136

102

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“…The newly detected hydride species are SH + (Menten et al 2011), OH + (Wyrowski et al 2010), H 2 O + (Ossenkopf et al 2010), H 2 Cl + , HCl + (De Luca et al 2012), SH , and, most recently, ArH + (Barlow et al 2013;Schilke et al 2014). OH + and H 2 O + were also observed extensively in extragalactic sources (van der Werf et al 2010;Weiß et al 2010;González-Alfonso et al 2013).…”

Section: Introductionmentioning

confidence: 98%

Detection of extragalactic argonium, ArH⁺, toward PKS 1830−211

Müller

Schilke

et al. 2015

A&A

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Context. Argonium has recently been detected as a ubiquitous molecule in our Galaxy. Model calculations indicate that its abundance peaks at molecular fractions in the range of 10 −4 to 10 −3 and that the observed column densities require high values of the cosmic ray ionization rate. Therefore, this molecular cation may serve as an excellent tracer of the very diffuse interstellar medium (ISM), as well as an indicator of the cosmic ray ionization rate. Aims. We attempted to detect ArH + in extragalactic sources to evaluate its diagnostic power as a tracer of the almost purely atomic ISM in distant galaxies. Methods. We obtained ALMA observations of a foreground galaxy at z = 0.89 in the direction of the lensed blazar PKS 1830−211. Results. Two isotopologs of argonium, 36 ArH + and 38 ArH + , were detected in absorption along two different lines of sight toward PKS 1830−211, known as the SW and NE images of the background blazar. The argonium absorption is clearly enhanced on the more diffuse line of sight (NE) compared to other molecular species. The isotopic ratio 36 Ar/ 38 Ar is 3.46 ± 0.16 toward the SW image, i.e., significantly lower than the solar value of 5.5.Conclusions. Our results demonstrate the suitability of argonium as a tracer of the almost purely atomic, diffuse ISM in high-redshift sources. The evolution of the isotopic ratio with redshift may help to constrain nucleosynthetic scenarios in the early Universe.

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“…The 526 GHz transition has also been detected in absorption in the diffuse interstellar medium towards various distant star-forming regions (Godard et al 2012). The 683 GHz transition of SH + has been detected in absorption towards Sgr B2(M) from the ground with the Carbon Heterodyne Array of the MPIfR (CHAMP+) receiver of the Atacama Pathfinder Experiment 12 m telescope (APEX; Menten et al 2011).…”

Section: Introductionmentioning

confidence: 99%

The chemistry of ions in the Orion Bar I. – CH⁺, SH⁺, and CF⁺

Nagy

Tak

Ossenkopf

et al. 2013

A&A

203

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Context. The abundances of interstellar CH + and SH + are not well understood as their most likely formation channels are highly endothermic. Several mechanisms have been proposed to overcome the high activation barriers, including shocks, turbulence, and H 2 vibrational excitation. Aims. Using data from the Herschel Space Observatory, we studied the formation of ions, in particular CH + and SH + in a typical high UV-illumination warm and dense photon-dominated region (PDR), the Orion Bar. Methods. The HIFI instrument on board Herschel provides velocity-resolved line profiles of CH + 1-0 and 2-1 and three hyperfine transitions of SH + 1 2 −0 1 . The PACS instrument provides information on the excitation and spatial distribution of CH + by extending the observed CH + transitions up to J = 6-5. We compared the observed line intensities to the predictions of radiative transfer and PDR codes. Results. All CH + , SH + , and CF + lines analyzed in this paper are seen in emission. The widths of the CH + 2-1 and 1-0 transitions are of ∼5 km s −1 , significantly broader than the typical width of dense gas tracers in the Orion Bar (∼2-3 km s −1 ) and are comparable to the width of species that trace the interclump medium such as C + and HF. The detected SH + transitions are narrower compared to CH + and have line widths of ∼3 km s −1 , indicating that SH + emission mainly originates in denser condensations. Non-LTE radiative transfer models show that electron collisions affect the excitation of CH + and SH + and that reactive collisions need to be taken into account to calculate the excitation of CH + . Comparison to PDR models shows that CH + and SH + are tracers of the warm surface region (A V < 1.5) of the PDR with temperatures between 500 and 1000 K. We have also detected the 5-4 transition of CF + at a width of ∼1.9 km s −1 , consistent with the width of dense gas tracers. The intensity of the CF + 5-4 transition is consistent with previous observations of lower-J transitions toward the Orion Bar.Conclusions. An analytic approximation and a numerical comparison to PDR models indicate that the internal vibrational energy of H 2 can explain the formation of CH + for typical physical conditions in the Orion Bar near the ionization front. The formation of SH + is also likely to be explained by H 2 vibrational excitation. The abundance ratios of CH + and SH + trace the destruction paths of these ions, and indirectly, the ratios of H, H 2 , and electron abundances as a function of depth into the cloud.

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Submillimeter absorption from SH⁺, a new widespread interstellar radical,¹³CH⁺and HCl

Cited by 118 publications

References 104 publications

Astrochemistry of dust, ice and gas: introduction and overview

Astrochemistry of dust, ice and gas: introduction and overview

Detection of extragalactic argonium, ArH⁺, toward PKS 1830−211

The chemistry of ions in the Orion Bar I. – CH⁺, SH⁺, and CF⁺

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Submillimeter absorption from SH+, a new widespread interstellar radical,13CH+and HCl

Cited by 118 publications

References 104 publications

Astrochemistry of dust, ice and gas: introduction and overview

Astrochemistry of dust, ice and gas: introduction and overview

Detection of extragalactic argonium, ArH+, toward PKS 1830−211

The chemistry of ions in the Orion Bar I. – CH+, SH+, and CF+

Contact Info

Product

Resources

About

Submillimeter absorption from SH⁺, a new widespread interstellar radical,¹³CH⁺and HCl

Detection of extragalactic argonium, ArH⁺, toward PKS 1830−211

The chemistry of ions in the Orion Bar I. – CH⁺, SH⁺, and CF⁺