The effect of the initial elemental abundance on gas-grain chemical models

Shalabiea, Osama M.

doi:10.1051/0004-6361:20010323

Cited by 10 publications

(9 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nearly 80% of the studied molecules reach the peak of their abundances before 10 5 years, suggesting that the molecular cloud collapses before the chemical balance is reached. Comparison with other works (e.g., Shalabiea 2001) show that our model produces similar results for the molecular abundances at the gas phase when we consider a molecular cloud having solar metallicity. However, these estimates are not yet consistent with observations for many molecules studied, showing that only gas-phase reactions underestimate the abundance of several molecules.…”

Section: Resultssupporting

confidence: 77%

Evolution of the abundance of biomolecules in the interstellar medium at the gas phase

Penteado

Rocha–Pinto

2009

Proc. IAU

View full text Add to dashboard Cite

Abstract. Interstellar clouds are the sites where many molecules believed important for the early life are produced. The collapse of such clouds may give birth to stars hosting planetary systems. During the formation of such systems, molecules formed in the molecular cloud, aggregated into grains, can be incorporated in protoplanets, influencing the chemical evolution of the environment, probably affecting the chances for appearance of life on rocky planets located at the stellar habitable zones. Moreover, small bodies, like comets, can carry some of these molecules to inner planets of their systems. Using astrochemical equations, we describe the evolution of the abundance of such molecules at the gas phase from several initial interstellar compositions. These varying initial chemical compositions consider the change of the elemental abundances predicted by a self-consistent model of the chemical evolution of the Galaxy. A system of first order differential equations that describes the abundances of each molecule is solved numerically. This poster describes an innovative attempt to link the astrochemistry equations with the Galactic chemical evolution.

show abstract

Section: Resultssupporting

confidence: 77%

Evolution of the abundance of biomolecules in the interstellar medium at the gas phase

Penteado

Rocha–Pinto

2009

Proc. IAU

View full text Add to dashboard Cite

show abstract

“…As discussed in Sect. 3.1.1, a significant enhancement of SiO in molecular gas has been attributed to heavy shock processing of grains in starburst galaxies where values of X(SiO) up to a few 10 −10 have been reported on scales of several hundred pc (García-Burillo et al 2000, 2001. The CND abundances of SiO estimated here are significantly larger than those reported for starbursts, however; this is further evidence that silicon chemistry in the CND is not being driven by star formation.…”

Section: Sio In Xdrmentioning

confidence: 42%

“…With the inclusion of dust-grain chemistry in time-dependent models, Shalabiea & Greenberg (1996) were able to fit at "early times" (t 10 6 yr) HCN/CO ∼ a few 10 −3 with values less restrictive for the oxygen depletion. The overall consequences of selective oxygen-depletion in the chemistry of molecular clouds have been more extensively studied in the framework of gas-phase (Terzieva et al 1998;Ruffle et al 1998) and gas-grain chemical models (Shalabiea 2001). The primary effect of an oxygen underabundance is a reduced formation of CO.…”

Section: N(hcn)/n(co) N(cs)/n(co) N(hcn)/n(hco + ) N(cn)/n(hcn) Nmentioning

confidence: 99%

Molecular gas chemistry in AGN

Usero

García‐Burillo

Fuente

et al. 2004

A&A

180

293

View full text Add to dashboard Cite

Abstract. There is observational evidence that nuclear winds and X-rays can heavily influence the physical conditions and chemical abundances of molecular gas in the circumnuclear disks (CND) of Active Galactic Nuclei (AGN). In this paper we probe the chemical status of molecular gas in the CND of NGC 1068, a prototypical Seyfert 2 galaxy. Precedent claims that the chemistry of molecular gas in the nucleus of NGC 1068 is abnormal by galactic standards were based on the high HCN/CO luminosity ratio measured in the CND. Results from new observations obtained in this survey have served to derive abundances of molecular species such as SiO, CN, HCO + , HOC + , H 13 CO + and HCO. These estimates are complemented by a re-evaluation of molecular abundances for HCN, CS and CO, based on previously published single-dish and interferometer observations of NGC 1068. We report on the first detection of SiO emission in the CND of NGC 1068. The estimated large abundance of SiO in the CND, X(SiO) ∼ (5−10) × 10 −9 , cannot be attributed to shocks related to star formation, as there is little evidence of a recent starburst in the nucleus of NGC 1068. Alternatively, we propose that silicon chemistry is driven by intense X-ray processing of molecular gas. We also report on the first extragalactic detection of the reactive ion HOC + . Most remarkably, the estimated HCO + /HOC + abundance ratio in the nucleus of NGC 1068, ∼30-80, is the smallest ever measured in molecular gas. The abundances derived for all molecules that have been the subject of this survey are compared with the predictions of models invoking either oxygen-depletion or X-ray chemistry in molecular gas. Our conclusions favour an overall scenario where the CND of NGC 1068 has become a giant X-ray Dominated Region (XDR).

show abstract

“…Furthermore, astrochemistry is inherently non-linear, so the results can be very sensitive to the input parameters such as abundances (see e.g. Shalabiea, 2001;Agúndez & Wakelam, 2013). This also needs to be understood and quantified, or at least more generally acknowledged.…”

Section: Future Instrumentationmentioning

confidence: 99%

Synthetic observations of star formation and the interstellar medium

Haworth

Glover

Koepferl

et al. 2018

New Astronomy Reviews

View full text Add to dashboard Cite

Synthetic observations are playing an increasingly important role across astrophysics, both for interpreting real observations and also for making meaningful predictions from models. In this review, we provide an overview of methods and tools used for generating, manipulating and analysing synthetic observations and their application to problems involving star formation and the interstellar medium. We also discuss some possible directions for future research using synthetic observations.

show abstract

The effect of the initial elemental abundance on gas-grain chemical models

Cited by 10 publications

References 39 publications

Evolution of the abundance of biomolecules in the interstellar medium at the gas phase

Evolution of the abundance of biomolecules in the interstellar medium at the gas phase

Molecular gas chemistry in AGN

Synthetic observations of star formation and the interstellar medium

Contact Info

Product

Resources

About