Cyanopolyynes as indicators of late-time chemistry and depletion in star-forming regions

Ruffle, D. P.; Hartquist, T. W.; Taylor, Stephen D.; Williams, D. A.

doi:10.1093/mnras/291.1.235

Cited by 54 publications

(34 citation statements)

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“…The NH 3 abundance, for example, remains relatively high (10 −7 with respect to H 2 ) until 3 × 10 7 yr in model P1 and at least 10 8 yr in model P2, while for HC 3 N the accretion actually causes a secondary "late-time" abundance peak of (2-5) × 10 −9 after ∼10 7 yr. This result, which holds for all cyanopolyynes, was first noted by Ruffle et al (1997).…”

Section: Cold Cloudssupporting

confidence: 61%

“…Earlier models of TMC-1 (e.g. Ruffle et al 1997;Markwick et al 2000;Hartquist et al 2001) have included accretion onto and desorption from grain surfaces. Our gas-grain model does provide a detailed description for differential depletion rates through cosmic ray desorption (Hasegawa & Herbst 1993), which yields varying desorption rates for individual species based on the strength of their attachment to grain particles.…”

Section: Tmc-1mentioning

confidence: 99%

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The abundance of gaseous H$_{\mathsf 2}$O and O$_{\mathsf 2}$ in cores of dense interstellar clouds

Roberts

Herbst

2002

A&A

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Abstract.We have used chemical models that include both gas-phase and grain-surface processes to try to understand the low water and molecular oxygen abundances inferred from SWAS observations towards dense molecular clouds. The models represent an improvement over pure gas-phase chemistries in that they are more realistic, and they are largely successful at reproducing the low O 2 abundances. For cold clouds, such as TMC-1 and L134N, the limits on the H 2 O abundance are met by the models only after relatively long periods of accretion (10 6 -10 7 yr), but we show that ground-based observations of these clouds do not necessarily contradict these ages, especially for L134N. If the upper limits on the H 2 O abundance were to be revised downwards, however, or if water were to be observed in the cold clouds at the same level as in some star-forming regions, then even heavier depletions would be required. For this reason, the low H 2 O abundance observed by SWAS in ρ Oph cannot be reproduced by the models without calculating unphysically low abundances of CO.

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Section: Cold Cloudssupporting

confidence: 61%

Section: Tmc-1mentioning

confidence: 99%

The abundance of gaseous H$_{\mathsf 2}$O and O$_{\mathsf 2}$ in cores of dense interstellar clouds

Roberts

Herbst

2002

A&A

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“…HC 3 N in particular increases significantly when depletion is effective (cf. Ruffle et al 1997). Gwenlan et al (2000) reached a similar conclusion when discussing the chemistry of HC 3 N for TMC-1.…”

Section: Starless Cores or Cores With Little Evidence Of Star-formationmentioning

confidence: 76%

Interstellar oxygen chemistry

Viti¹,

Roueff²,

Hartquist³

et al. 2001

A&A

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Abstract. We present results of chemical models for a variety of types of regions shown by SWAS observations to contain less O2 and H2O than previously expected. We identify time-dependent models for which O2 and H2O abundances meet the SWAS constraints and for which calculated abundances of other species are in harmony with measurements made primarily at millimeter wavelengths. The phases of acceptable composition are transient in these time-dependent models but are of very substantial length in many models for which CO and N2 are assumed to be returned promptly and unaltered to the gas phase though other species, except for H2 and He, freeze-out onto the dust. We also consider whether the presence of bistability in some steady-state models can account for the SWAS and other observations.

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“…As seen in Figure 3, the abundance of HC 3 N responds markedly as freeze-out occurs. 15 The first peak in the curve is simply a reflection of the initial condition that much of the carbon was atomic, whereas the second peak is a consequence of freeze-out.…”

Section: The Chemistry Of Star Formationmentioning

confidence: 99%

The Chemistry of Star-Forming Regions

Williams

Hartquist

1999

Acc. Chem. Res.

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David A. Williams was born in 1937 in Nottingham, U.K., educated at Queen's University Belfast (B.Sc., Ph.D.); he obtained a D.Sc. from the University of Manchester in 1980. He established a molecular astrophysics group at UMIST, Manchester, formerly was a professor at UMIST 1984-1994 and currently is Perren Professor of Astronomy at University College London. Current interests include cosmic dust. Thomas W. Harquist was born 1954 in Redwood City, CA, and was eduated Rice University (B.A.) and Harvard University (M.A., Ph.D.). He was a postdoc at Harvard, a Royal Society Jaffe ´Donation Fellow in University College London, assistant professor University of Maryland, senior research scientist MPI fuer extraterrestrische Physik, and lecturer University of Leeds, U.K. His main interest is diffuse astrophysical media.

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Cyanopolyynes as indicators of late-time chemistry and depletion in star-forming regions

Cited by 54 publications

References 0 publications

The abundance of gaseous H$_{\mathsf 2}$O and O$_{\mathsf 2}$ in cores of dense interstellar clouds

The abundance of gaseous H$_{\mathsf 2}$O and O$_{\mathsf 2}$ in cores of dense interstellar clouds

Interstellar oxygen chemistry

The Chemistry of Star-Forming Regions

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