The effect of varying cosmic ray ionization rates on dark cloud chemistry

P. R.A. Farquhar; T. J. Millar; Eric Herbst

doi:10.1093/mnras/269.3.641

The effect of varying cosmic ray ionization rates on dark cloud chemistry

P. R.A. Farquhar, T. J. Millar, Eric Herbst

Research output: Contribution to journal › Article › peer-review

34 Citations (Scopus)

Abstract

We investigate the effects of varying the cosmic ray ionization rate in chemical models of dense interstellar clouds. In the absence of such ionization, a scenario which may be applicable to dark cloud cores, we find that chemi-ionization is able to drive a limited ion-neutral chemistry. Models of clouds in starburst galaxies, which may have enhanced cosmic ray fluxes, are also investigated and enable an upper limit to be derived for the cosmic ray ionization rate in M82. The derived value, which is about 700 times the typical value for Galactic molecular clouds, is in good agreement with that necessary to explain the recent observations of C I in this galaxy.

Original language	English
Pages (from-to)	641-648
Number of pages	8
Journal	Monthly Notices of the Royal Astronomical Society
Volume	269
Issue number	3
DOIs	https://doi.org/10.1093/mnras/269.3.641
Publication status	Published - 01 Jan 1994
Externally published	Yes

Keywords

Abundances
Clouds - cosmic rays - ISM
Molecular processes - ISM
Molecules -galaxies

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1093/mnras/269.3.641

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title = "The effect of varying cosmic ray ionization rates on dark cloud chemistry",

abstract = "We investigate the effects of varying the cosmic ray ionization rate in chemical models of dense interstellar clouds. In the absence of such ionization, a scenario which may be applicable to dark cloud cores, we find that chemi-ionization is able to drive a limited ion-neutral chemistry. Models of clouds in starburst galaxies, which may have enhanced cosmic ray fluxes, are also investigated and enable an upper limit to be derived for the cosmic ray ionization rate in M82. The derived value, which is about 700 times the typical value for Galactic molecular clouds, is in good agreement with that necessary to explain the recent observations of C I in this galaxy.",

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AU - Herbst, Eric

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N2 - We investigate the effects of varying the cosmic ray ionization rate in chemical models of dense interstellar clouds. In the absence of such ionization, a scenario which may be applicable to dark cloud cores, we find that chemi-ionization is able to drive a limited ion-neutral chemistry. Models of clouds in starburst galaxies, which may have enhanced cosmic ray fluxes, are also investigated and enable an upper limit to be derived for the cosmic ray ionization rate in M82. The derived value, which is about 700 times the typical value for Galactic molecular clouds, is in good agreement with that necessary to explain the recent observations of C I in this galaxy.

AB - We investigate the effects of varying the cosmic ray ionization rate in chemical models of dense interstellar clouds. In the absence of such ionization, a scenario which may be applicable to dark cloud cores, we find that chemi-ionization is able to drive a limited ion-neutral chemistry. Models of clouds in starburst galaxies, which may have enhanced cosmic ray fluxes, are also investigated and enable an upper limit to be derived for the cosmic ray ionization rate in M82. The derived value, which is about 700 times the typical value for Galactic molecular clouds, is in good agreement with that necessary to explain the recent observations of C I in this galaxy.

KW - Abundances

KW - Clouds - cosmic rays - ISM

KW - Molecular processes - ISM

KW - Molecules -galaxies

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JF - Monthly Notices of the Royal Astronomical Society

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ER -

The effect of varying cosmic ray ionization rates on dark cloud chemistry

Abstract

Keywords

ASJC Scopus subject areas

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