Mapping observations of sulfur-containing carbon-chain molecules in Taurus Molecular Cloud 1 (TMC-1)

Hirahara, Yasuhiro; Suzuki, Hiroko; Yamamoto, Satoshi; Kawaguchi, Kentarou; Kaifu, Norio; Ohishi, Masatoshi; Takano, Shuro; Ishikawa, Shinya; Masuda, Akimasa

doi:10.1086/171605

Cited by 156 publications

(175 citation statements)

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“…Without surface reactions, abundances drop by about two orders of magnitude. Some chemical models predict an increase in the abundance when the amount of depletion of other gas phase species (like CO) is high (e.g., Hirahara et al 1992;Ruffle et al 1997;Caselli et al 1998). Observed abundances do not show such a trend as does our model, in fact our model predicts slightly higher abundances with decreasing envelope mass due to sublimation of HC 3 N from grain mantles and lower freeze-out rates.…”

Section: Hc 3 Ncontrasting

confidence: 57%

Modeling the chemical evolution of a collapsing prestellar core in two spatial dimensions

Weeren¹,

Brinch

Hogerheijde³

2009

A&A

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Context. The physical conditions in a collapsing cloud can be traced by observations of molecular lines. To correctly interpret these observations the abundance distributions of the observed species need to be derived. The chemistry in a collapsing molecular cloud is not in a steady state as the density and temperature evolve. We therefore need to follow chemical reactions, both in the gas phase and on dust grains, as well as gas-grain interactions, to predict the abundance distributions. Aims. Our aim is to model the abundances of molecules, in the gas phase and on grain mantles in the form of ice, from prestellar core collapse to disk formation. We want to investigate the need for grain surface reactions and compare our results with observed abundances, column densities, and ice-mantle compositions. Methods. We use a 2-dimensional hydrodynamical simulation as a physical model from which we take the density, temperature, and the flow of the gas. Trace particles, moving along with the gas, are used to follow the chemistry during prestellar core collapse and disk formation. We calculated abundance profiles and column densities for various species. The evolution of these abundances and the composition of ices on grain mantles were compared to observations and we tested the influence of grain surface reactions on the abundances of species. We also investigated the initial abundances to be adopted in more detailed modeling of protoplanetary disks by following the chemical evolution of trace particles accreting onto the disk. Results. Fractional abundances of HCO + , N 2 H + , H 2 CO, HC 3 N, and CH 3 OH from our model with grain surface reactions provide a good match to observations, while abundances of CO, CS, SO, HCN, and HNC show better agreement without grain surface reactions. The observed mantle composition of dust grains is best reproduced when we include surface reactions. The initial chemical abundances to be used for detailed modeling of a protoplanetary disk are found to be different from those in dark interstellar clouds. Ices with a binding energy lower than about 1200 K sublimate before accreting onto the disk, while those with a higher binding energy do not.

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Section: Hc 3 Ncontrasting

confidence: 57%

Modeling the chemical evolution of a collapsing prestellar core in two spatial dimensions

Weeren¹,

Brinch

Hogerheijde³

2009

A&A

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“…The resultant column density of HCS + in TMC-1 was determined to be (1.0 ± 0.3) × 10 13 cm −2 (Hirahara et al 1992). In the present work, HCS + was weakly detected in L1527 for the first time, as shown in the spectrum (d) of Figure 1.…”

Section: Sulfur-bearing Molecules So and Hcs +supporting

confidence: 53%

“…The [HCS + ]/[CS] ratio is an index parameter for the dissociative recombination of sulfur-bearing molecules in the chemical model calculation (Millar & Herbst 1990;Montaigne et al 2005). For the dark cloud, the observed ratio of 0.044 at the cyanopolyyne peak in TMC-1 (Hirahara et al 1992) was larger than the calculated ratio of 0.015 by Millar & Herbst (1990) and those of 0.01-0.001 by Montaigne et al (2005). For the low-mass star-forming region, the observed ratio in L1527 was determined to be 0.06 using the column density of HCS + in the present observation and that of CS reported by Jørgensen et al (2002Jørgensen et al ( , 2004.…”

Section: Sulfur-bearing Molecules So and Hcs +mentioning

confidence: 99%

A SEARCH FOR INTERSTELLAR CARBON-CHAIN ALCOHOL HC₄OH IN STAR-FORMING REGION L1527 AND DARK CLOUD TMC-1

Araki

Takano

Yamabe

et al. 2011

ApJ

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We report a sensitive search for the rotational transitions of the carbon-chain alcohol HC 4 OH in the frequency range 21.2-46.7 GHz in the star-forming region L1527 and the dark cloud TMC-1. The motivation was laboratory detection of HC 4 OH by microwave spectroscopy. Despite achieving rms noise levels of several millikelvin in the antenna temperature using the 45 m telescope at Nobeyama Radio Observatory, the detection was not successful, leading to 3σ upper limits corresponding to the column densities of 2.0 × 10 12 and 5.6 × 10 12 cm −2 in L1527 and TMC-1, respectively. These upper limits indicate that [HC 4 OH]/[HC 5 N] ratios are less than 0.3 and 0.1 in L1527 and TMC-1, respectively, where HC 5 N is an HC 4 -chain cyanide and HC 4 OH is a hydroxide. These ratios suggest that the cyano carbon-chain molecule dominates the hydroxyl carbon-chain molecule in L1527 and TMC-1. This is contrary to the case of saturated compounds in hot cores, e.g., CH 3 OH and CH 3 CN, and can be a chemical feature of carbon-chain molecules in L1527 and TMC-1. In addition, the column densities of the "unsubstituted" carbon-chain molecule C 4 H and the sulfur-bearing molecules SO and HCS + were determined from detected lines in L1527.

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“…4a. In the density range between 10 4 cm −3 and 10 5 cm −3 , which is appropriate for TMC-1 (Hirahara et al 1992;Hirota et al 1998) −20 and 250 +80 −50 , respectively, from the obtained column densities, where the column density of CCH is evaluated from the intensities of the two weakest hyperfine components. These are almost consistent with those derived from the LVG model analysis.…”

Section: Abundance Anomaly Of the 13 C Species Of Cchmentioning

confidence: 99%

Abundance anomaly of the¹³C species of CCH

Sakai

Saruwatari

Sakai³

et al. 2010

A&A

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Aims. We have observed the N = 1−0 lines of CCH and its 13 C isotopic species toward a cold dark cloud, TMC-1 and a star-forming region, L1527, to investigate the 13 C abundances and formation pathways of CCH. Methods. The observations have been carried out with the IRAM 30 m telescope. Results. We have successfully detected the lines of 13 CCH and C 13 CH toward the both sources and found a significant intensity difference between the two 13 C isotopic species. The [C 13 CH]/[ 13 CCH] abundance ratios are 1.6 ± 0.4 (3σ) and 1.6 ± 0.1 (3σ) for TMC-1 and L1527, respectively. The abundance difference between C 13 CH and 13 CCH means that the two carbon atoms of CCH are not equivalent in the formation pathway. On the other hand, the [CCH]/[C 13 CH] and [CCH]/[ 13 CCH] ratios are evaluated to be larger than 170 and 250 toward TMC-1, and to be larger than 80 and 135 toward L1527, respectively. Therefore, both of the 13 C species are significantly diluted in comparison with the interstellar 12 C/ 13 C ratio of 60. The dilution is discussed in terms of a behavior of 13 C in molecular clouds.

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Mapping observations of sulfur-containing carbon-chain molecules in Taurus Molecular Cloud 1 (TMC-1)

Cited by 156 publications

References 0 publications

Modeling the chemical evolution of a collapsing prestellar core in two spatial dimensions

Modeling the chemical evolution of a collapsing prestellar core in two spatial dimensions

A SEARCH FOR INTERSTELLAR CARBON-CHAIN ALCOHOL HC₄OH IN STAR-FORMING REGION L1527 AND DARK CLOUD TMC-1

Abundance anomaly of the¹³C species of CCH

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Mapping observations of sulfur-containing carbon-chain molecules in Taurus Molecular Cloud 1 (TMC-1)

Cited by 156 publications

References 0 publications

Modeling the chemical evolution of a collapsing prestellar core in two spatial dimensions

Modeling the chemical evolution of a collapsing prestellar core in two spatial dimensions

A SEARCH FOR INTERSTELLAR CARBON-CHAIN ALCOHOL HC4OH IN STAR-FORMING REGION L1527 AND DARK CLOUD TMC-1

Abundance anomaly of the13C species of CCH

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A SEARCH FOR INTERSTELLAR CARBON-CHAIN ALCOHOL HC₄OH IN STAR-FORMING REGION L1527 AND DARK CLOUD TMC-1

Abundance anomaly of the¹³C species of CCH