CS Depletion in Prestellar Cores

Kim, Shinyoung; Lee, Chang-Won; Maheswar, G.; Tafalla, M.; Sohn, Jungjoo; Kim, Gwanjeong; Kim, Mi-Ryang; Soam, Archana; Myers, Philip C.

doi:10.3847/1538-4357/ab774d

Cited by 12 publications

(13 citation statements)

References 28 publications

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“…Besides, the abundance of CS tends to be enhanced in turbulent regions, and CS emission is consistent with the chemical effects expected in shocked regions (Hartquist et al 1980;Zhou et al 1989;Suzuki et al 1992;Luo et al 2019). The depletion of the CS molecule (Vastel et al 2018;Kim et al 2020) in the dense region of F1-M will also make the CS emission look more extended.…”

Section: Maps Of the Pmo 137msupporting

confidence: 71%

A search for cloud cores affected by shocked carbon chain chemistry in L1251

Liu,

Wu,

Zhang

et al. 2021

Preprint

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We searched for shocked carbon chain chemistry (SCCC) sources with C 3 S abundances surpassing those of HC 5 N towards the dark cloud L1251, using the Effelsberg telescope at K-band (18 -26 GHz). L1251-1 and L1251-3 are identified as the most promising SCCC sources. The two sources harbor young stellar objects. We conducted mapping observations towards L1251-A, the western tail of L1251, at λ ∼3 mm with the PMO 13.7 m and the NRO 45 m telescopes in lines of C 2 H, N 2 H + , CS, HCO + , SO, HC 3 N and C 18 O as well as in CO 3-2 using the JCMT. The spectral data were combined with archival data including Spitzer

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Section: Maps Of the Pmo 137msupporting

confidence: 71%

A search for cloud cores affected by shocked carbon chain chemistry in L1251

Liu,

Wu,

Zhang

et al. 2021

Preprint

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“…The depletion of CS has been widely studied in starless cores, and the X(CS)/X(N 2 H + ) abundance ratio has been proposed as an evolutionary diagnostic for these objects (Tafalla et al 2002;Tafalla & Santiago 2004;Hirota & Yamamoto 2006;Heithausen et al 2008;Kim et al 2020). Our data show that the CS abundance decreases almost linearly with the density for almost three orders of magnitude.…”

Section: Csmentioning

confidence: 52%

Gas phase Elemental abundances in Molecular cloudS (GEMS)

Rodríguez-Baras

Fuente

Riviére-Marichalar

et al. 2021

A&A

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Gas phase Elemental abundances in Molecular CloudS (GEMS) is an IRAM 30 m Large Program designed to provide estimates of the S, C, N, and O depletions and gas ionization degree, X(e−), in a selected set of star-forming filaments of Taurus, Perseus, and Orion. Our immediate goal is to build up a complete and large database of molecular abundances that can serve as an observational basis for estimating X(e−) and the C, O, N, and S depletions through chemical modeling. We observed and derived the abundances of 14 species (13CO, C18O, HCO+, H13CO+, HC18O+, HCN, H13CN, HNC, HCS+, CS, SO, 34SO, H2S, and OCS) in 244 positions, covering the AV ~3 to ~100 mag, n(H2) ~ a few 103 to 106 cm−3, and Tk ~10 to ~30 K ranges in these clouds, and avoiding protostars, HII regions, and bipolar outflows. A statistical analysis is carried out in order to identify general trends between different species and with physical parameters. Relations between molecules reveal strong linear correlations which define three different families of species: (1) 13CO and C18O isotopologs; (2) H13CO+, HC18O+, H13 CN, and HNC; and (3) the S-bearing molecules. The abundances of the CO isotopologs increase with the gas kinetic temperature until TK ~ 15 K. For higher temperatures, the abundance remains constant with a scatter of a factor of ~3. The abundances of H13 CO+, HC18 O+, H13 CN, and HNC are well correlated with each other, and all of them decrease with molecular hydrogen density, following the law ∝ n(H2)−0.8 ± 0.2. The abundances of S-bearing species also decrease with molecular hydrogen density at a rate of (S-bearing/H)gas ∝ n(H2)−0.6 ± 0.1. The abundances of molecules belonging to groups 2 and 3 do not present any clear trend with gas temperature. At scales of molecular clouds, the C18O abundance is the quantity that better correlates with the cloud mass. We discuss the utility of the 13CO/C18O, HCO+/H13CO+, and H13 CO+/H13CN abundance ratios as chemical diagnostics of star formation in external galaxies.

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“…Therefore, it has been largely used as density and column density tracer in the interstellar medium in our Galaxy and external galaxies (see, e.g. Snell et al 1984;Lapinov et al 1998;Kim et al 2020;Martín et al 2005;Bayet et al 2009;Kelly et al 2015). Moreover, CS is the only S-bearing molecule routinely detected in protoplanetary disks and therefore the main tracer of the sulfur abundance in the primordial material to form planets (Agúndez et al 2018;Le Gal et al 2019).…”

Section: Cs Chemical Networkmentioning

confidence: 99%

Gas phase Elemental abundances in Molecular cloudS (GEMS)

Bulut

Roncero

Aguado

et al. 2021

A&A

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Context. Carbon monosulphide (CS) is among the most abundant gas-phase S-bearing molecules in cold dark molecular clouds. It is easily observable with several transitions in the millimeter wavelength range, and has been widely used as a tracer of the gas density in the interstellar medium in our Galaxy and external galaxies. However, chemical models fail to account for the observed CS abundances when assuming the cosmic value for the elemental abundance of sulfur. Aims. The CS+O → CO + S reaction has been proposed as a relevant CS destruction mechanism at low temperatures, and could explain the discrepancy between models and observations. Its reaction rate has been experimentally measured at temperatures of 150−400 K, but the extrapolation to lower temperatures is doubtful. Our goal is to calculate the CS+O reaction rate at temperatures <150 K which are prevailing in the interstellar medium. Methods. We performed ab initio calculations to obtain the three lowest potential energy surfaces (PES) of the CS+O system. These PESs are used to study the reaction dynamics, using several methods (classical, quantum, and semiclassical) to eventually calculate the CS + O thermal reaction rates. In order to check the accuracy of our calculations, we compare the results of our theoretical calculations for T ~ 150−400 K with those obtained in the laboratory. Results. Our detailed theoretical study on the CS+O reaction, which is in agreement with the experimental data obtained at 150–400 K, demonstrates the reliability of our approach. After a careful analysis at lower temperatures, we find that the rate constant at 10 K is negligible, below 10−15 cm3 s−1, which is consistent with the extrapolation of experimental data using the Arrhenius expression. Conclusions. We use the updated chemical network to model the sulfur chemistry in Taurus Molecular Cloud 1 (TMC 1) based on molecular abundances determined from Gas phase Elemental abundances in Molecular CloudS (GEMS) project observations. In our model, we take into account the expected decrease of the cosmic ray ionization rate, ζH2, along the cloud. The abundance of CS is still overestimated when assuming the cosmic value for the sulfur abundance.

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CS Depletion in Prestellar Cores

Cited by 12 publications

References 28 publications

A search for cloud cores affected by shocked carbon chain chemistry in L1251

A search for cloud cores affected by shocked carbon chain chemistry in L1251

Gas phase Elemental abundances in Molecular cloudS (GEMS)

Gas phase Elemental abundances in Molecular cloudS (GEMS)

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